Warm Outlets: How Warm is Too Warm? - Page 1
Forum section: electronics / beginners

author: tommygdawg
author_rank: Contributor
timestamp: February 12, 2016, 12:51:23 am
content: Hey all,Basic question. Running a light off a 20 amp circuit. Light draws 14-16 amps continuous. The area surrounding very near to the wall plug (like within a couple inches at most of where I plug the light in) gets slightly warm after running the light for 30-60 minutes. Warm as in, warm enough to feel a difference when I put my hand up a few more inches, but not hot by any means. Is this normal? Or does it mean that the wires inside the wall are dangerously hot and I'm only slightly feeling it on the outside?Thanks!

author: IanB
author_rank: Super Contributor
timestamp: February 12, 2016, 12:54:30 am
content: What country?

author: tommygdawg
author_rank: Contributor
timestamp: February 12, 2016, 01:17:46 am
content: USA. I've measured at multiple outlets in my house and it typically comes out between 118-122 volts.

author: uncle_bob
author_rank: Unknown
timestamp: February 12, 2016, 01:18:17 am
content: HiWall sockets wear out. They wear out faster if you do crazy things pulling cords from them. They wear out faster if you buy the ones that (for some odd reason) are on sale for 1/10th the price of a name brand.The reason you have electricians that understand all this is so you can call them up and say "can you come take a look at this?". If its a concern, give the guy a call. It might cost you a few bucks. He'll look at all your sockets and (if he's honest and most of them are) give you a pretty good idea of what you should do throughout your dwelling.That said, a little warm (as i define a little warm) is not unusual at 3/4 load. Pulling 3/4 load from a single outlet is considered "unusual" by most of the rating agencies.Bob

author: djacobow
author_rank: Super Contributor
timestamp: February 12, 2016, 01:44:44 am
content: Quote from: uncle_bob on February 12, 2016, 01:18:17 amMy experience with electricians is that they understand very little and operate largely by rules of thumb and "something an older electrician told them one time."That said, though I personally would not first call an electrician to diagnose a problem like this, if you do not know what you're doing, you absolutely should do so. Nobody here -- myself included -- wants to bear the responsibility of your house burning down.

author: IanB
author_rank: Super Contributor
timestamp: February 12, 2016, 01:58:00 am
content: In the USA, wall sockets can be manufactured at cost of 5 cents and sold for 50 cents, especially when homes are being built and the things are being installed by the thousands.In my home, for example, they used sockets where the wires were just pushed into holes in the back and you hoped they didn't fall out. Also, the plugs would sometimes just fall out of the front as well because all spring tension was lost on the contacts. You can imagine how these things could overheat on heavy loads.I replaced them with higher quality sockets and made sure the wires were attached with solid screw terminals done up tight.

author: Delta
author_rank: Super Contributor
timestamp: February 12, 2016, 01:58:51 am
content: Get a proper mains voltage, son....120v? Pah! 😁

author: uncle_bob
author_rank: Unknown
timestamp: February 12, 2016, 02:04:20 am
content: HiI guess we all have had our own experiences along the way. I do my own electrical work. If the house burns, it's my own darn fault. I could do the HVAC and plumbing, I prefer not to. Even for the electrical, I occasionally have to make a call. (It's tough to replace a switch in the US when you are Japan). My experience with all the guys I've dealt with has been positive. What they have suggested has made sense and none of it was over the top. It's possible I've just been lucky or I live in the right place..... There is the *slight* possibility that they are pretty good a figuring out who they can BS.Bob (the 6'4" 300 lb guy you probably don't want to piss off ...)

author: uncle_bob
author_rank: Unknown
timestamp: February 12, 2016, 02:06:01 am
content: Quote from: Delta on February 12, 2016, 01:58:51 amHiDid we mention that it's 60 Hz and not 50Boy, the opportunity to use "real British" wall plugs ... neat-o ....Bob

author: Delta
author_rank: Super Contributor
timestamp: February 12, 2016, 02:11:36 am
content: Quote from: uncle_bob on February 12, 2016, 02:06:01 amBest in the world though mate! (Let's not go there....! Although you will not find a domestic plug anywhere in the world that can induce as much pain into a bare or socked foot as an upturned BS1363!)

author: uncle_bob
author_rank: Unknown
timestamp: February 12, 2016, 02:21:00 am
content: Quote from: Delta on February 12, 2016, 02:11:36 amHiWell we wouldn't be running a thread about a BS1363 getting warm at 2KW would we?Bob

author: djacobow
author_rank: Super Contributor
timestamp: February 12, 2016, 02:31:14 am
content: Quote from: uncle_bob on February 12, 2016, 02:04:20 amIndeed. My last experience with a sparky was when I wanted to have a backfeed outlet installed for an emergency generator. They need to be installed with a physical interlock that keeps the backfeed from being closed while the main breaker is also closed. (They sell special hardware for this purpose for many common panels.) He claimed to have never in his 30 years seen a residential generator installation, and was unfamiliar with the rules. He declined the job.A time before that, I had built a small shed to be an electronics workshop and ham shack. It is a good 50' from my house and double that from the main panel. I had dug a 2' deep ditch for the conduit from the house to the shed. I told the guy I wanted 40 amps to a subpanel in the shed and I'd take it from there. Too much work for a an hour or two and $300 and not enough for a longer period. I think he wanted to bill all the time for the wiring in the walls and outlets. He also didn't want to work with PVC, even underground, even though it is perfectly legal in this jurisdiction. (Must be sch 80 above ground). In the end he didn't bid or even return calls.Regarding the BS thing. Yes, it would be a fun "sting" operation to call electricians with canned electrical problems, with different actors: a man, a woman, etc.

author: tommygdawg
author_rank: Contributor
timestamp: February 12, 2016, 02:32:02 am
content: Thanks much for all the responses, everyone. I'll pull the socket out of the wall and check the wire gauge as well as see if it gets hot when it's not in the wall. I will say the breaker is rated at 20amps for that socket and it's labeled as a 20a socket (it's a GFCI), so I doubt they'd use 12 gauge wire on that. But you never know.Alternatively, could this be caused by the light? The actual plug for the light got warm as well.

author: djacobow
author_rank: Super Contributor
timestamp: February 12, 2016, 02:37:44 am
content: Quote from: tommygdawg on February 12, 2016, 02:32:02 am#12 is ok for 20A. It's #14 or smaller that is an issue.For $20 you could also just replace the outlet. At the least, tighten the screw, and if it is the push in back-wire type of connection, consider removing the wires and screwing them down ye olde fashioned way.I've seen GFCI's self-destruct. It happened in my house the other day when I wasn't home. Wife reported one of our outlets started buzzing like a solenoid buzzer and died. I don't know why caused it to start to fail, but the coil that holds the contacts closed was cooked by the time I got home and pulled it.

author: tommygdawg
author_rank: Contributor
timestamp: February 12, 2016, 02:43:15 am
content: Quote from: djacobow on February 12, 2016, 02:37:44 amI guess I just like to make strong choices and put #10 on everythingThat GFCI sounds terrifying! Glad it didn't cause any additional damage. Have you experienced anything like that before?

author: Primus
author_rank: Newbie
timestamp: February 12, 2016, 02:49:01 am
content: Quote from: djacobow on February 12, 2016, 01:44:44 amUnderstand very little? I understand you're talking "in general", but I really don't understand how anyone would think this. I've only got 8 years of experience in the field, but the depth of knowledge required for this type of work is not trivial. With industrial/commercial you have everything from VFDs, motor controls, switching controls, back-up power generation and the related transfer switches. My mentors have been very knowledgeable and it requires just as much to learn this line of work as it does my electronics hobby.Any electrician worth their salt knows the basics about electricity, included the requisite trig and algebra... no, we're not pulling out calculus reference sheets in the fields or calculating anything that requires a physics major. But, just for example... what if you need to know the load of an unbalanced 3-phase panel neutral, well, you need a little at least a working knowledge of vectors and how to add/subtract the vector components. So, basic electricity, basic physics, basic math skills and a mechanical aptitude and you have a decent apprentice electrician.This isn't mentioning the full gamut of wiring techniques, materials and just pure amount of things you will never, ever learn from a book, you simply have to practice it under knowledgeable people.As for the OPs question, the energy you feel radiating from your could be some voltage drop across the lights extension cord, but you really shouldn't be having too much drop from your branch-circuit conductors or the outlet itself. It really just depends on how hot it's getting as to whether it's an issue; remove the cover and do a visual inspection, check for any discoloration of the wiring or device. We call them "glowing joints" in the trade, and it's a very common troubleshooting annoyance for us, and I've seen many a melted things in my time, including receptacles.

author: djacobow
author_rank: Super Contributor
timestamp: February 12, 2016, 02:51:53 am
content: Quote from: tommygdawg on February 12, 2016, 02:43:15 amI have not. But my house was brought up to 2008 code before I bought it and as a result, about 1.2 zillion GFCI's were installed -- they're not just for garages and bathrooms anymore. So the chance of a GFCI failure has certainly increased.It's educational to take one apart. The are surprisingly complex devices. They have a current transformer wound with two primaries to detect differential current on the neutral and hot lines. The secondary feeds some electronics which, in turn, drive a solenoid that holds a mechanical contact in place as long as the unit is in the "untripped" state. When you push in the reset button of a GFCI you are actually forcing the contacts back over and re-energizing the ckt, which also drives the holding coil so that the circuit stays latched -- unless there is a fault, in which case it won't latch. Anyway, there is a good reason they cost $15-20 rather than the $0.75-$3 of a typical outlet.ALL that said ... I don't think this fault would have resulted in a fire, as ultimate the unit died open. I was not there to see whether there was heat, spark, fire, flame, but inspecting the unit, I only saw the burnt solenoid wire.By the way, regarding your question about warmth on the appliance side. I think -- but am not sure -- that the rules for gauge of the cords that feed appliances are more lax than the in-wall requirements. So, for example, a 15A tea kettle that is only designed to be on for a few minutes at a time, could be wired with thin wire that heats noticeable. In fact, my kettle is just so. Anyway, a little warm on the plug and cord side is a little less worrisome since you can observe it directly, and you don't have to worry about heating someplace hidden like your wall.

author: djacobow
author_rank: Super Contributor
timestamp: February 12, 2016, 02:58:18 am
content: Quote from: Primus on February 12, 2016, 02:49:01 amI'm sure it varies. People doing industrial practice might be a little more up on their game than some of the residential guys I've run into. Also, there is a lot of the NEC that one can avoid knowing precisely by just using rules of thumb that "round up" safely. Why consult a fill table when you can just be super conservative and use bigger or more parallel conduits? Residential customer won't know the difference and it's allowed.

author: Primus
author_rank: Newbie
timestamp: February 12, 2016, 02:59:04 am
content: Quote from: djacobow on February 12, 2016, 02:37:44 amYeah, I have a collection of about 200 different types of GFCIs I've dissected. It's pretty interesting to see all the different ways electrical equipment fails! And yeah, just say no to using the stab-lock terminals on an outlet - simple stuff like that has made me a lot of money over the years.Quote from: djacobow on February 12, 2016, 02:58:18 amI've done my fair share of residential work, but yeah, residential only guys tend to be the least informed.

author: djacobow
author_rank: Super Contributor
timestamp: February 12, 2016, 03:07:01 am
content: Quote from: Primus on February 12, 2016, 02:59:04 amCool. I've only taken apart one. Do they vary much in design. I was surprised to see so much mechanical stuff, and just a lot of copper overall. Generally, a pretty beefy design.Quote from: Primus on February 12, 2016, 02:59:04 amIt was unfair of me to paint the whole profession based on a few interactions. I'm sure it's like any profession, with folks who take it very seriously for their whole careers, those who slide by with the least knowledge possible, and lots of people in between.:-)

author: tommygdawg
author_rank: Contributor
timestamp: February 12, 2016, 03:11:04 am
content: Thanks again for the thoughts! The cable/plug for the light does get warm, so it could very well be the heat generated from that radiating into the wall. The unit is a Chinese HID light. Perhaps it might be in my best interest to rewire it with a higher end cable. It claims it's rated for 15 amps, but that is right on the edge of what I'm drawing.

author: rrinker
author_rank: Super Contributor
timestamp: February 12, 2016, 04:21:46 am
content: My old house, I replaced all the outlets, most of them wouldn't even hold a plug. I used the more expensive ones as replacements. This house - I have to do the same thing. One of the ones in the master bedroom literally fell apart, the surround of the top half came right off. And others are of similar dubious quality. So, next project, start replacing outlets around the house. Such a fun job - not.

author: tommygdawg
author_rank: Contributor
timestamp: February 12, 2016, 05:01:37 am
content: Quote from: rrinker on February 12, 2016, 04:21:46 amWow, that's a lot of work. How old were the two houses and their respective electrical systems before you did the work? My house is only around 10 years old so it should be fairly up to snuff.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: February 12, 2016, 06:35:51 am
content: Quote from: tommygdawg on February 12, 2016, 02:43:15 amTry making a reliable connection to an outlet with #10. It can be a little tricky to pack a box even with #12. If you read the back of your outlet, you'll find that the lugs are only rated up to #12 anyway. Bigger ain't necessarily better.

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 12, 2016, 06:58:36 am
content: At the very least, take the socket out of the wall box and check that the wire connections are tight.If they are the push-in variety, replace with the screw-down type. Some plugs allow both kinds of connections.You didn't mention the vintage of the house. There was a period where aluminum wires were used.During a time of very expensive copper, many houses were wired with aluminum.Many (most?) of those aluminum wiring jobs have become loose because aluminum has a larger temperature expansion than copper.So at the very east they need re-tightening. ALL OF THEM! Up to and including the breaker panel.OF COURSE you shut off the power while you are working on mains wiring unless you are attempting suicide or arson.Remember that if THAT outlet is getting warm, there may be others in the house.And some of them may produce conditions sufficient to start a fire.You are lucky you got a warning before anything serious happens.

author: forrestc
author_rank: Unknown
timestamp: February 12, 2016, 07:08:39 am
content: Quote from: djacobow on February 12, 2016, 02:31:14 amI wonder if part of the problem was that where you put a subpanel in you must (in many localities) feed the outbuilding with a 60A feed, and 40A wouldn't be permitted. This of course varies from location to location thanks to lack of clarity in the code in relation to this.Still, if was me, I'd say 'PVC, great, I love PVC, but we need to put a 60A panel and feed in to meet electrical code. this means 6AWG, or a bit larger to avoid drop so we need to size the conduit and cable appropriately". But again, I'm not a sparky, just someone who has had to deal with the code a lot.-forrest

author: forrestc
author_rank: Unknown
timestamp: February 12, 2016, 07:21:50 am
content: Quote from: tommygdawg on February 12, 2016, 12:51:23 amJust my $0.02, adding and repeating what others have said:Whenever I get heating of any part of the electrical system of the house, I worry. A lot.Something is higher resistance than it should be. Assuming correct wire sizing in the house (i.e. 12GA wire on a 20A circuit), the most likely cause is either a bad plug or poor quality connections in that outlet box. It could also be a poor quality connection between the plug and the cable. Does the plug itself get warm?At a minimum, I'd pull the plug out and investigate. And while I had it out, I'd replace it with a good quality specification or commercial grade plug. I prefer the ones which are 'backwire', not to be confused with 'back stab' or as I like to call them 'poke and pray'. The backwire ones use a screw and plate to hold down the wire, and not some hokey compression fitting. I also would ensure that the circuit did *not* go through the plug - instead a pigtail should come from the wiring in the back of the box to the plug. That way a plug failure does not cause a circuit failure.

author: rrinker
author_rank: Super Contributor
timestamp: February 12, 2016, 01:55:42 pm
content: Quote from: tommygdawg on February 12, 2016, 05:01:37 amThe previous one was not that old at all - was built around 1990 and I was living there in 2004. The previous owners were definitely the type of people who didn't take care of anything, so most of the really loose ones were almost certainly caused by abuse, not poor quality. Others in the same room that hardly got used were fine, but I just replaced them all - took a while, it was a rather large house. This house was built in 73 or 74, and as far as I can tell these are the original outlets and are mostly just worn out. Shouldn't be as big a deal since this is a much smaller house, and the kitchen already has new outlets since I redid it when I moved in, also updating to GFCI on the counters, not required because of grandfathering but I'm not going to skimp on that sort of thing. The bigger project here will be doing the basement, I want to require everything but the appliances to support my planned model railroad, with a single switch shutting off everything but the overhead lights (too much for one switch, so it will have to be some sort of low voltage switch operating a contactor in the box). That way there's no danger of equipment failing while unattended, or quitting working on something and leaving a soldering iron plugged it for days.

author: TimFox
author_rank: Super Contributor
timestamp: February 12, 2016, 02:31:57 pm
content: Quick question: is the outlet near a heating duct? I had a similar problem with a wall switch for a 100 W ceiling fixture, where the switch box was very close to the forced-air duct in the wall.

author: djacobow
author_rank: Super Contributor
timestamp: February 12, 2016, 04:57:31 pm
content: Quote from: forrestc on February 12, 2016, 07:08:39 amCould be. I think, though, he wanted to do just the opposite. I believe it is legal to feed an out-building that is within a certain distance of the main house (eg, freestanding garage) with a simple branch circuit and no subpanel (or local ground), so that seemed the easiest to him. He could not understand why I wanted 40A. Maybe he thought I was building a grow house? In the end, I don't think I'll ever draw 40A from that building, but it's nice to know I could. (starting large tools that I don't own but maybe one day?) IIRC, I did use #6. 300' of that wire was most the expensive part of that project. #8 has the required ampacity, but the full-load voltage drop would have been unacceptable.Quote from: forrestc on February 12, 2016, 07:08:39 amYes, and code is a funny thing. There is the NEC, there is the local code which may adopt the NEC in total or as a "base" and then there are the local inspectors who seem to have their own ideas. A neighbor of mine is a newish GC. He has lots of stories of inspectors both making up little requirements that can't be found written anywhere, or letting other things slide because they "do not really matter." I suspect being a successful contractor in part is about knowing the local variation, formal and informal. We just got a new roof on our house and the city inspector made his assessment from the street...

author: djacobow
author_rank: Super Contributor
timestamp: February 12, 2016, 04:58:55 pm
content: Quote from: TimFox on February 12, 2016, 02:31:57 pmWow, that is a good question! When you're an on EE website, everything looks like an EE problem ... but maybe it's not!

author: Cubdriver
author_rank: Unknown
timestamp: February 12, 2016, 05:29:35 pm
content: Quote from: forrestc on February 12, 2016, 07:21:50 amI much prefer the back wired ones with the clamping plates too - far simpler to install without the need to loop the wire and get it wrapped around the screw head and down into the little recess. Doing that is especially fun on things like 4 way switches with 4 terminals with connections that need to wrap one way on one side and the opposite on the other.Pigtailing too is definitely the way to go IMO. Not only does it prevent a poor connection at a receptacle terminal from taking out everything downstream of it, it also means that the receptacle terminals need only carry the current being drawn from that particular receptacle. If they're daisy chained, the first connection passes ALL the current for that receptacle and everything beyond it (the worst case); each subsequent one downstream carries all the current not drawn off before it (less total current, but still more than it needs to carry). When they're pigtailed, the main current goes through a (hopefully) nice tight splice. Fewer screw connections and less chance of something coming loose.-Pat

author: IanB
author_rank: Super Contributor
timestamp: February 12, 2016, 05:39:44 pm
content: Quote from: Cubdriver on February 12, 2016, 05:29:35 pmI get the reasoning for this, but when I replaced all the sockets in my house there were about 100 of them to do and it took ages to complete as it was. I used the back wired sockets and yes, there was lots of daisy chaining. However, I observed the sockets had a brass bus bar for continuity that was at least the same cross section as the wire, and with the back wired sockets it is possible to insert two wires into one screw terminal which minimizes the current path between the wires in any case.If I had attempted to pigtail them all it would have taken forever. There are times when pragmatism wins out over ideals.

author: Audioguru
author_rank: Super Contributor
timestamp: February 12, 2016, 06:11:32 pm
content: I agree that the "push the wire in the hole and hope it makes a good contact" is Mickey Mouse and is asking for a fire.Amateurs and newbie electricians screw down a wire the wrong way around then it becomes loose.I have never seen a cheapo Chinese copy of an American electrical receptacle.

author: tommygdawg
author_rank: Contributor
timestamp: February 13, 2016, 04:01:40 am
content: Just an update: pulled the socket out and ran the light for close to an hour with the socket out of the wall. Flipped off the breaker and then felt up the wires leading out of the socket. They were marginally warm but not hot by any means, but would that not be expected for a constant 14-16 amp draw after running for nearly an hour?It was really stiff wire, unlabeled but around the same thickness #12.

author: IanB
author_rank: Super Contributor
timestamp: February 13, 2016, 04:05:17 am
content: The place to look for warmth is junctions and contact points. For example, where the wires are connected to the outlet, the outlet itself (where the plug pins contact the internal spring contacts), and where the appliance flex is joined to the plug inside the molded casing. These are places where high resistance can occur.

author: tommygdawg
author_rank: Contributor
timestamp: February 13, 2016, 04:14:38 am
content: Quote from: IanB on February 13, 2016, 04:05:17 amThose places felt about as warm as the wires themselves. It was basically an even distribution of heat throughout. The main pos/neg wires out of the socket were also twisted with plastic caps on top to the wires proceeding down into the wall. Those caps felt about as warm, if not a slight bit more warm than the rest. Good or bad? Indifferent?I didn't remove the wars from the socket itself, they were in fact screwed down to the inside of the socket.

author: IanB
author_rank: Super Contributor
timestamp: February 13, 2016, 04:46:57 am
content: Quote from: tommygdawg on February 13, 2016, 04:14:38 amThose are wire nuts. They are a common source of poor connections. It wouldn't hurt to redo them.If you unscrew the wire nuts you will find the wires twisted together underneath. Make sure they are twisted together well (use pliers for this). Then screw the plastic wire nut back on top until you feel resistance. Then keep on screwing it downreally harduntil the wires underneath twist right down to the insulation. A common fault is failing to twist on the wire nut hard enough. You should twist it until it hurts your fingers.

author: Ian.M
author_rank: Super Contributor
timestamp: February 13, 2016, 06:49:19 am
content: Plug in a short 20A rated extension lead, in good condition with clean pins and plug the appliance into that. If the excess heat problem follows the appliance plug, its the plug or appliance lead that's bad. If it stays at the socket, and you've eliminated loose connections, the socket's gone bad - change it.

author: forrestc
author_rank: Unknown
timestamp: February 13, 2016, 11:35:42 am
content: Quote from: IanB on February 13, 2016, 04:46:57 amOne of the best things I've ever bought is the ratcheting version of one of these:(See about 1:30 in the video if you're impatient).Getting a nut tight enough isn't a problem anymore with this.They also have drill attachments. That seems like overkill.

author: necessaryevil
author_rank: Regular Contributor
timestamp: February 13, 2016, 01:26:13 pm
content: This sounds very bad to me, assuming that the heat is caused by the electricity and not by the lamp itself. Wire or outlets shouldn't get warm, or, at least, you shouldn't be able to notice it by touching it.By the way, do you live in a lighthouse ;-)? 20 amps at 120v, that's a whopping 2400w. What kind of lamp is that?

author: uncle_bob
author_rank: Unknown
timestamp: February 13, 2016, 02:02:59 pm
content: Quote from: tommygdawg on February 13, 2016, 04:14:38 amHiConnectors carry current. They have contact resistance. They way you get a current rating is to define a maximum temperature. You then work back from there through the temperature rise on the connector to figure out if it is ok or not. The tables you see of "this connector does this" are generally done for a specific temperature rise (10,20,40C). There are other things (wet contact issues) that also get into it. If you don't plug in the light with it turned on, they aren't an issue.It is not at all uncommon to see a connector that is "rated for 20A" in a catalog, running fine for years and years at 5X that. The rating is at 10C rise. The particular application is fine with a 50C rise. Connectors "die" when the insulation goes over temperature. That's rarely going to happen below 105C. Connectors with 200C or higher insulation do exist.So, is 10C "warm"? If you are in a 20C room, the connector did not get to body temperature. That may or may not be warm. IR thermometers are made because most people are not very good at the "touch it and see" approach for exact temperature measurement. Indeed there are some who can come very close. Don't place bets on this sort of thing.The standard advice on any electrical issue is always the same. If it worries you, replace it or have it looked at by a pro. We're talking about an outlet that costs less than $3 around here.Bob

author: tooki
author_rank: Super Contributor
timestamp: February 13, 2016, 06:54:21 pm
content: Quote from: Audioguru on February 12, 2016, 06:11:32 pmOf course not, cuz that's what most receptacles in USA already are! When you buy a pack of 10 outlets for $4.99 at Lowe's, you know damned well they're not a quality Made in USA product. But even a (supposedly made in USA) Leviton industrial grade receptacle is just $6.When I first moved to Switzerland (from USA) I was absolutely shocked (no pun intended) at how expensive light switches and outlets here are. Now, in all fairness, part of explanation is due to lack of economies of scale, since Switzerland uses its own outlet (Type J) — for a country with a population just below that of New York City!Consequently, a standard 3-socket wall receptacle here cannot be had for under $20 (and that's for the Chinese-made one), and a European-made one can be double. (And don't even ask what a GFCI outlet or wall dimmer costs. Just don't go there.)But even in the rest of Europe where the common Schuko outlet does have massive economies of scale, they're still far more expensive than American ones.

author: DivineChaos
author_rank: Regular Contributor
timestamp: February 13, 2016, 09:02:25 pm
content: Well, my US vacuum cleaner is a 10a 1200w type and after 15 minutes or so of cleaning, the cord and the outlet are quite warm, no matter which plug I put it into, even the GFCI one in the bathroom.Honestly, it does worry me, but it seems normal and safe, because after years and years of using a vacuum to clean my house, nothing has ever happened.

author: tommygdawg
author_rank: Contributor
timestamp: February 14, 2016, 03:00:32 am
content: Quote from: DivineChaos on February 13, 2016, 09:02:25 pmI've noticed this as well with vacuum cleaners. I guess the question is how long is it safe to run such equipment?Also fun fact after doing some research. GFCI's tend to always be a little bit warm. I noticed that even when nothing is plugged into mine they always feel warm. I got the thermometer out and measured about a consistent 5 degree higher temperature than the surrounding wall on all my GFCIs. I googled this and apparently it's a common phenomenon due to their electronics on the inside.

author: uncle_bob
author_rank: Unknown
timestamp: February 14, 2016, 03:08:03 am
content: Quote from: tommygdawg on February 14, 2016, 03:00:32 amHiIf a 5F rise counts as warm, then yes, all your electrical gear will feel warm.The insulators in there are rated for at least 180F. That's a lot more than warm. To get that hot, something needs to be very wrong. In the context of outlets, 100F (in a normal 70F room) is "warm".Bob

author: Xplode
author_rank: Contributor
timestamp: February 14, 2016, 05:47:37 pm
content: I'm an electrician by trade and going back to some of the earlier posts, I agree that not all electricians are smart. Construction/Installation electricians aren't as generally well versed with the problems and fixes as a service electrician would be. I work more in the service end of things, and often in commercial and industrial settings.That said, the guys that decline a job because they're not sure (ie that generator) are smart. They know their limits, and are willing to admit it. Be afraid of the cowboy who just does it anyway. never ends well.The other guy that turned down the job even though you'd dug and laid the pipe, probably just wasn't interested because the job was now too small. I can't make money if I have to field calls, drive out, look at it, bid on it, then pickup materials and go back and install it for only a couple hundred bucks. Its just not worth it unfortuanately, can't keep the machine turning so to speak. However, in my jurisdiction at least, a homeowner is allowed to pull a permit and do their own electrical work so long as the follow the codes.Now back to the original topic - the warm plug.There are several reasons, and fixes, to get to the bottom of this. Most suggestions have already been covered, so this is just confirming and agreeing.1) turn off the power and pull out the receptacle. Ensure the wires are in fact large enough (should be #12 awg copper). Make sure they're under the screws and not stabbed in to the holes in the back (I've received so much easy money from this one)2) Check for signs of heat on the wire where it connects to the receptacle, and where any splices are made in the box. Discoloration and added or reduced "shininess" compared to the rest of the wiring is a sign of trouble. Cracking or flaking insulation is a sign of long term heat damage as well. Copper being a bit darker and not shiny is NOT an issue. natural copper oxidization is ok, so long as it isn't combined with signs of heat damage in the insulation.3) Replace the receptacle. Go to a proper electrical supplier and buy a good quality plug from a large manufacturer. Ask for "commercial grade" or "spec grade" or "hospital grade" (local terms might be different than here). It will cost $6 instead of $.89. But will have a nice metal back strap, feel absolutely solid, and the internals will be significantly stronger.4) Check your cord end - does it look good? Old cord ends with metal fatigued pins can cause grief as well showing signs of heating in the receptacle that aren't the receptacle's fault. If in doubt, buy a good cord end (again, not dollar store. go to an electrical supplier, and buy a proper 20A cord end). Sometimes 15A cord ends show up on manufactured devices due to the regulations for manufacturing being quite different than the regulations for electrical installers (ie your vacuum cord being warm - its anticipated that the duty cycle is so low on the vacuum cleaner that it will be ok. - commercial units don't warm up quite the same)That should get you fixed up. If you replace any receptacles/cord ends/etc make sure you re-connect it correctly. The "Neutral" side and the "Hot" side can not be safely interchanged on the receptacle or cord ends. (swapping ends could energize the light socket so you get a good wake-up blast when changing bulbs)Hope that helped!

author: Cubdriver
author_rank: Unknown
timestamp: February 14, 2016, 06:58:43 pm
content: Xplode -re your #4 suggestion about buying a 20A cord end - by that are you suggesting a replacement plug for the cord? If so, wouldn't a 20A unit (here in North America) be a NEMA 5-20P, with the neutral blade at 90 degrees relative to the hot (the 'winking' plug) to prevent it being plugged in to a 15A receptacle? If replacing the plug is what you're suggesting, I'd think he'd be better off with a good quality 15A one, otherwise unless he has 20A receptacles he won't be able to plug it in anywhere.Everything else I wholeheartedly agree with,especiallyabout not cheaping out on the receptacles. Spend a few bucks each and get good ones - this is not the place to use things from the 99 cent store!-Pat

author: uncle_bob
author_rank: Unknown
timestamp: February 14, 2016, 07:26:50 pm
content: Quote from: Cubdriver on February 14, 2016, 06:58:43 pmHiAccording to the original post, the light pulls up to 16A continuous. If it does not already have a 20A plug on it, that raises some significant questions about the basic design of the light.Bob

author: bitslice
author_rank: Frequent Contributor
timestamp: February 14, 2016, 07:37:25 pm
content: Quote from: forrestc on February 12, 2016, 07:21:50 amI've just watched a US video on 'pigtailing' because I wasn't sure what was involved (I'm in the UK), and the problem seems to be the odd way of designing the sockets.You are kind of forced to use those bulky cable nuts to terminate wires instead of terminating them into the socket because they are screw-downs that can only carry one wire.Then having to wrap electrical tape around the outside just in case?Then having to work out if I still need a ground wire by guessing if the wiring is running in metal conduit or not. EeekIn the UK I can just strip back the insulation from a single cable, bend it over and screw down into the socket.I don't need to cut a wire at all so the cable can carry its rated amps regardless of how many terminations I make.If I do need to make a termination we have heavily over-engineered termination boxes that isolate everything. I've not seen the same item in the USA?I like a lot about America, but the electrical system is a teeny bit scary.

author: uncle_bob
author_rank: Unknown
timestamp: February 14, 2016, 07:58:20 pm
content: Quote from: bitslice on February 14, 2016, 07:37:25 pmHiIn a residential environment, pretty much nothing made in the last 50 years runs in conduit or metal jacketed cable (it went out when I was a kid). The default assumption is that you have a ground wire in the (plastic jacket) cable and you use it. Along the way they figured out that wire nuts are not a good idea for grounds. You now have to use a copper crimp.So that all sounds simple right?Well not so much.Electrical rules and regs are the province of the local town hall. There are layers on top of that at the state and federal level, but most of it comes at a very local level. What you can do in this town, may or may not be what you can do (get away with) in the next town. Because of this, you can see some really odd stuff.The next layer is that you may or may not be able to work on your own home. When working on your own home, you may or may not be required to get it inspected. Depending on the inspector, what gets inspected may or may not have a lot of relation to the rules.Scared yet?Ok so, next time I'm at the 90 year old mother in law's house maybe I'll shoot some pictures. It's been re-wired multiple times. In some cases I suspect that the choice of materials was based on the scrap heap at the local steel plant. Each time I'm there I hack a way at a bit more of it. Each time I come back ... somebody else has "improved" things a bit. I never seem to get ahead.Did I mention the "grandfather clause?". More or less, for certain things, you only need to comply with the rules as they existed when the house was built. If your farm house is the original as chartered by somebody named "King Charles" that clause may cover a lot more than wires. Yes I had neighbors that were covered under that particular rule from Charles II. They also had the right to do a number of odd things related to hunting and fishing.Lots of twists and turns ....Bob

author: Cubdriver
author_rank: Unknown
timestamp: February 14, 2016, 08:03:59 pm
content: Quote from: uncle_bob on February 14, 2016, 07:26:50 pmWhoops!! Not having read from the beginning of the thread for a while, I forgot that point and was basing my comments on the vacuum cleaner mentioned more recently. Since we're referring to the light, in the immortal words of Emily Litella - Never mind... If the light is drawing over 15A, then it should definitely be fitted with a 5-20P to prevent it from being plugged into a 15A branch circuit, if nothing else.-Pat

author: uncle_bob
author_rank: Unknown
timestamp: February 14, 2016, 08:21:21 pm
content: Quote from: Cubdriver on February 14, 2016, 08:03:59 pmHiI seem to vaguely recall something about branch current on a circuit. A number like 80% comes to mind. If I'm not hallucinating (again ... I swear I took those meds ...) that would suggest that a light with a load current of over 12 A or 1440 W should have a 20A plug on it. Could be 90%. I very much doubt it's 100%....The regs are always fun to read, but I think that's what this:The total cord- and plug-connected load must not exceed 80% of the receptacle rating [210.21(B)(2)].Is talking about. If it's not going at it directly, it is hitting it indirectly.Bob

author: bitslice
author_rank: Frequent Contributor
timestamp: February 14, 2016, 08:44:24 pm
content: Quote from: uncle_bob on February 14, 2016, 07:58:20 pmHeh, I was just watching someone use a wire nut because two ground (#14?) wires don't fit in a US outlet. Yep, a crimp sounds better.QuoteAh, that would explain a lot, I wouldn't trust my local council to lick envelopes.For something that is all basically the same technology I'd expect some kind of Federal? standard, but that sort of presupposes that the people at Federal level are any better than the the local council, (I gather common core education has its critics).Maybe it just needs some American innovation in socket design?Naturally I'm going to favour something I'm used to, but British sockets do seem to be more robust and easier to wire?Although amazingly our Consumer units were, up until Jan 2016, allowed to be made of non fire retardant plastic, whereas American ones are all metal. I don't know why we screwed that one up so badlyQuoteWe have that now, it's patronising, but then looking at my Father in Law, it is essential for humanity.But then Australians are not allowed to change a lightbulb or cable an office with Cat5QuoteI think everyone in the UK kind of accepted that our rubber wiring had to go, and plug in fuses were outdated when GFI's were so cheap. That was probably a golden time to be an electrician.

author: tommygdawg
author_rank: Contributor
timestamp: February 14, 2016, 08:50:17 pm
content: Quote from: uncle_bob on February 14, 2016, 07:26:50 pmI should say that the lamp draws more around 14A continuous when at full power and after having warmed up. the 16A figure was a high end that I was using to give some leeway. It probably does draw more around 16 or higher though when first striking the bulb since it's a discharge lamp and will occasionally trip 15A circuits in the house when I first turn on the ballast.The thoughts here have been incredibly helpful. I'm convinced that it's the plug off the ballast that's causing heating issues. I've tried it in numerous outlets for lengthy times and all have slightly warmed after running the light for a couple of hours. Using the IR thermometer I read about probably 10-13F raise in temperature from ambient room temp on the wall socket.

author: uncle_bob
author_rank: Unknown
timestamp: February 14, 2016, 09:06:24 pm
content: Quote from: tommygdawg on February 14, 2016, 08:50:17 pmHiIf it's not a 20A plug, it should be. Same thing with the wire to the plug. If it's 14 GA, it should be heavier. This sounds a lot like a lamp that was "upgraded" from a lower power design. The manufacturer either didn't think things through or they realized that a 20A plug would nuke sales ....either way ... not good.Bob

author: Cubdriver
author_rank: Unknown
timestamp: February 14, 2016, 09:36:31 pm
content: Quote from: uncle_bob on February 14, 2016, 07:58:20 pmIn my limited experience (pulling permits and rewiring my own house during a renovation), wiring codes are based on the NEC (National Electrical Code), with major revisions published about every three years if memory serves), which is supposed to by and large set minimum standards. Local jurisdictions can then tweak these standards for their use, but I believe that that tweaking is mostly to tighten rather than loosen the regs, though there are exceptions to this. One that I know if is that at the time of my work, my town followed the 2005 NEC. A literal reading of the NEC said that ALL circuits that feed outlets in bedrooms (receptacles, lighting, wired smoke alarm) must be AFCI protected (Art. 210.12). Local regs allowed the lighting and smoke alarm circuits to be protected by a standard breaker, as long as they served only that purpose and could not otherwise be connected to.And there are definitely a lot of twists and turns!-Pat

author: uncle_bob
author_rank: Unknown
timestamp: February 14, 2016, 09:47:41 pm
content: Quote from: Cubdriver on February 14, 2016, 09:36:31 pmHiIt's local politics. Nothing ever apples in all casesOne place I lived, the county (not the town) had never bothered to pass a building code. Oddly enough there was no default state code at that time either. The net result was that once you crossed the town line it was "anything goes". Yes, it was a thinly populated county and I doubt they had the staff or systems to do much more than they did. Really low taxes out in the county though .... i have no idea how anybody got insurance under those conditions.Bob

author: TimFox
author_rank: Super Contributor
timestamp: February 14, 2016, 09:51:58 pm
content: In the city of Chicago, the electrical code still requires metal conduit or equivalent for house wiring, and all industrial wiring that I have seen is in conduit. Similarly, GFIs are required in kitchens, bathrooms, outdoor outlets, etc.

author: Monkeh
author_rank: Super Contributor
timestamp: February 14, 2016, 10:02:53 pm
content: Quote from: uncle_bob on February 14, 2016, 07:58:20 pmIf it's not good enough for ground, it's not good enough for anything.

author: uncle_bob
author_rank: Unknown
timestamp: February 14, 2016, 10:08:30 pm
content: Quote from: Monkeh on February 14, 2016, 10:02:53 pmHiThe issue is fault current in the event of a lightening strike. The supply leads are not expected to deal with that. Same issue as bonding to a ground rod.Bob

author: djacobow
author_rank: Super Contributor
timestamp: February 14, 2016, 10:45:18 pm
content: Quote from: Cubdriver on February 14, 2016, 09:36:31 pmJust to amplify for our international forum members, it's worth explaining the US system, which might seem strange to them. Our government is federated. That word actually means something, with both good and bad implications. To a first approximation, it means that the federal government can't do things that it isn't specifically allowed to do under the constitution. And yeah, building codes fall in that category.There is no national building code.The National Electric Code (NEC) is not a law, but a document created and maintained by the National Fire Protection Association, a private nonprofit organization. What gives the NEC the force of law is that governments that have appropriate jurisdiction (states, counties, cities) adopt it. As of now, the NEC is law in all 50 states having been adopted by /their/ legislatures. Furthermore, counties and cities can add their own stuff. Note, however, that given that the states have adopted it as law, a local government cannot UN-adopt the NEC. Sh*t flows downhill, as it were.In actuality, the federal government does often find ways to force its way even when it does not have strict jurisdiction. For example, they can withhold related or unrelated funding. They did this with the national speed limit. The feds had no right to set a national speed limit, so they instead said "ye shall set your speed limit at 55 lest we withdraw highway funding." Sometimes these carrot and stick approaches are challenged in the courts, and outcomes have gone both ways. In this case, it stuck, but eventually was repealed in 1995 through the normal political process.Someone brought up insurance. I think this is also a major unifying factor in setting codes, and probably has more influence than the federal government in such matters. If they won't insure it, you probably won't want to build it.I personally have mixed feelings about the NEC. On the face, it's almost certainly a very good thing overall, having saved many a structure from destruction. However, it grows every three years, and I strongly suspect they are chasing smaller and smaller returns (in terms of avoided fires) with ever more expensive interventions (like AFCI). The organizations most likely to show up to meetings (and to be on the board) to advocate for something new are: electricians, manufacturers, fire departments, and insurance companies -- all of which are in a position to suggest new expensive interventions and shift the costs of same onto someone else (builders, homeowners).

author: Monkeh
author_rank: Super Contributor
timestamp: February 14, 2016, 11:05:14 pm
content: Quote from: uncle_bob on February 14, 2016, 10:08:30 pmI don't see where surviving a lightning strike can come into the equation for such small conductors.There's a lot of very strange ideas in the NEC.

author: TimFox
author_rank: Super Contributor
timestamp: February 15, 2016, 12:07:39 am
content: If a wire nut opens up in a line or neutral connection, it's a nuisance but does not remove the safety ground from the entire system.In Chicago, the code requires a very firm clamp to the incoming water line near where it enters the building. The connection in my house is somewhat redundant: a large wire inside a 3/4" conduit, both of which connect to a clamp at the water pipe. There is also a required connection from the outside meter, through a similar connection, to a ground rod immediately below the meter.Having traveled abroad, and seen much weaker connections in some benighted countries, I did not argue with the electrician when he updated my house wiring last year.

author: Monkeh
author_rank: Super Contributor
timestamp: February 15, 2016, 12:13:36 am
content: Quote from: TimFox on February 15, 2016, 12:07:39 amExcept for the fire hazard..I understand the risks of a lost ground; I do not see the relevance of lightning strikes which are as likely to vaporise the WIRE on a small final circuit.A properly installed lightning rod is a much better investment than yet another termination method for conductors which can't be expected to survive lightning in the firstplace.

author: TimFox
author_rank: Super Contributor
timestamp: February 15, 2016, 12:19:55 am
content: If the loose line wire hits the conduit or outlet box, it should trip the circuit breaker.

author: uncle_bob
author_rank: Unknown
timestamp: February 15, 2016, 12:29:13 am
content: Quote from: Monkeh on February 15, 2016, 12:13:36 amHiA high current pulse generates heat. That is why you don't use solder or something like that on a ground system. A wire nut is not as good at high temperatures as a crimp. If the wire vaporizes ... sure you have an issue. If the strike induces a pulse (which is far more likely) you get a hot spot.Bob

author: forrestc
author_rank: Unknown
timestamp: February 15, 2016, 12:31:10 am
content: Quote from: bitslice on February 14, 2016, 07:37:25 pmNot sure which video you watched.A few points:Ground wire is required no matter what. Conduit, or not.In new wiring, every box gets all of the grounds crimped together with a crimp ring, then pushed in the back of the box, with a wire hanging out for the outlet. With the crimp ring and the appropriate tool, this becomes *very* solid connection wise. Generally the wire hanging out for the outlet is one of the wires that has been passed through the crimp ring.Then each set of current carrying conductors (i.e. hot and neutral) are tied together with compression connectors (aka wire nut). When used properly (and most laymen don't know how to use them properly), a wire nut is safe, and requires no additional electrical tape anywhere.When you're done, you have the 'permanent' wiring in the back of the box, and three wires hanging out of the front of the box for the receptical. The permanent wiring is never messed with again, and the pigtails are used to connect to the receptical.When done this way, it's safe and not a problem.

author: forrestc
author_rank: Unknown
timestamp: February 15, 2016, 12:53:32 am
content: Quote from: uncle_bob on February 15, 2016, 12:29:13 amI agree with what you said here, except I think that wire nuts generally have a bad wrap because people use them incorrectly. I think this is because the perception is that the metal in the wire nut is supposed to somehow help with the electrical connection. In reality, the purpose of wire nut is to compress the wires together together tightly. A correctly applied wire nut will result in a mechanical connection which is often not even reliant on the nut itself anymore to make a good electrical connection, other than perhaps to help keep the joint mechanically stable. The problem is that most people don't even come close to tightening them enough.Hint: If someone says proper application of a wire nut *requires* electrical tape to keep them on, they probably don't know what they're doing. My experience is that every time that I've seen taped wire nuts, none of them are tight enough and they're a fire waiting to happen.

author: uncle_bob
author_rank: Unknown
timestamp: February 15, 2016, 01:25:27 am
content: Quote from: forrestc on February 15, 2016, 12:53:32 amHiOdd you should mention tape.I'm pretty much convinced that my whole house was done as part of an apprentice training project. Here I see tape, not because the wires are not tight. I see it because they stripped them a bit to far ....Bob

author: Monkeh
author_rank: Super Contributor
timestamp: February 15, 2016, 02:01:19 am
content: Quote from: uncle_bob on February 15, 2016, 12:29:13 amI know Ohm's law, yes.If a wire nut is so poor a connection that it would fail so easily before the wire does, it is unsuitable for any task, ground or live.Crimping is actually considered unsuitable for solid-core wires of any reasonable size by most standards.

author: uncle_bob
author_rank: Unknown
timestamp: February 15, 2016, 02:08:26 am
content: Quote from: Monkeh on February 15, 2016, 02:01:19 amHiWell it's been pretty obvious from the start that you are not going to buy any wire nuts any time soon.Despite them being obviously an item that self destructs instantly, there are many billions of them happily doing the intended job over many decades. Odd how that works ....Bob

author: Monkeh
author_rank: Super Contributor
timestamp: February 15, 2016, 02:16:34 am
content: Quote from: uncle_bob on February 15, 2016, 02:08:26 amWell, seeing as I know of no reputable suppliers in the entire country who keep them.. I do have a standing request with a friend for a small assortment to put to actual tests next time he sends a package, though. I look forward to putting everyone's opinions, beliefs, and hearsay on the end of my welder and seeing what fails first.I never actually said they're bad, I said if they're considered unsuitable for joining one conductor I cannot see why they're suitable for any other. If they're so bad they cannot be trusted for ground, why can they be trusted where they're actually exposed to current flowing and continual heating and cooling cyles? That's actually arguing in favour of them, or at least trying to be neutral..

author: uncle_bob
author_rank: Unknown
timestamp: February 15, 2016, 02:24:56 am
content: Quote from: Monkeh on February 15, 2016, 02:16:34 amHiOk, we'll try this one more time:If the roaring flames are raging through the house and they hit the plastic nut, it melts and shorts. The insulation on the mains wires also melts and shorts. That's all fine and pretty much expected. Through the raging inferno, the copper crimp sheath over the tightly twisted ground leads does not melt. The twisted ground leads can not come apart. The ground circuit out lasts the rest of the system as the fire rages on (as it should).Bob

author: Monkeh
author_rank: Super Contributor
timestamp: February 15, 2016, 02:28:50 am
content: Quote from: uncle_bob on February 15, 2016, 02:24:56 amNo connector in use that I am aware of uses the insulation to maintain contact,includingwire nuts. Want to try again?

author: uncle_bob
author_rank: Unknown
timestamp: February 15, 2016, 02:38:31 am
content: Quote from: Monkeh on February 15, 2016, 02:28:50 amRead what I said, the plastic melts and the wires short. Using insulation to maintain connection was *not* mentioned above.

author: IanB
author_rank: Super Contributor
timestamp: February 15, 2016, 02:40:58 am
content: Quote from: uncle_bob on February 15, 2016, 02:24:56 amForgive me for being confused, but if the house is a raging inferno the integrity of the electrical ground system is about the last thing I care about...

author: Monkeh
author_rank: Super Contributor
timestamp: February 15, 2016, 02:41:09 am
content: Quote from: uncle_bob on February 15, 2016, 02:38:31 amQuoteThe steel insert inside the wire nut does not melt, either. In fact, the copper will melt first! The heat will of course affect the properties, but it should not do so particularly quickly.

author: forrestc
author_rank: Unknown
timestamp: February 15, 2016, 04:44:27 am
content: Quote from: Monkeh on February 15, 2016, 02:16:34 amHaving just recently started using crimps on the ground wires, I can see the benefit of the crimp sleeves. They connect the (normally bare) copper ground wires much more easily and securely, and more importantly, permanently. I can't say they're better or worse than wire nuts.For the record, unless it's a *very* recent change, I don't believe the NEC actually requires crimp for the ground connection in an electrical box. I searched through my copy of the NEC, and searched through the major changes in 2014, and couldn't find this requirement.

author: forrestc
author_rank: Unknown
timestamp: February 15, 2016, 04:54:31 am
content: Quote from: Monkeh on February 15, 2016, 02:01:19 amCrimping is another area which is asking for problems. With a correct crimp tool and lug pretty much any wire of any description can have a crimp lug attached. The problem is that once you get to a reasonable sized solid cable, suitable crimp lugs and crimpers are hard to find and not easily obtainable.BUT... I will take a properly applied crimp over a soldered and/or screw-terminated (aka clamp) wire any day. It should be noted that a properly applied crimp is one which has had enough pressure applied consistently around the crimp that the crimp effectively becomes welded to the conductor through pressure.

author: djacobow
author_rank: Super Contributor
timestamp: February 15, 2016, 06:20:56 am
content: Quote from: forrestc on February 15, 2016, 04:44:27 amThis is getting to the point I was trying to make before. Crimps might be better than wire nuts, but how much better _can_ they be? It's not like badly installed wire nuts burning down a houses on every block. We're way down in the noise.

author: Xplode
author_rank: Contributor
timestamp: February 15, 2016, 04:35:41 pm
content: I guess I'll weigh in again now that we're totally off topic (but the OP seems content).I've come across wire crimps in residential wiring (here in Canada) but it was all 30+ years old. We've moved away from crimps and I'm glad. Wire nuts are the best way to go, period. I've had to cut off the bonding crimps in boxes before to make changes to the wiring and it leaves me with even less copper to make the re-connect with. Wire nuts can be backed off, a 1/4 back-turn of the conductors bird-cages them slightly, and you can twist the new conductor into the group. Minimal fatigue strain on the copper, and a nice solid twisted connection with significantly more copper in contact with copper than a small crimp. I realize this is because I'm doing the connections properly, creating a "mechanically solid" connection (which is dictated by our NEC) before the wire-nut is applied. It is absolutely permanent if left untouched for years.I don't personally see the connection with the fire concerns of nut vs crimp, but I am curious to see this "welder test"Going waaaaaay back in the thread - the 20A 5-20P suggestion is valid. NEC usually dictates no more than 80% rated load connected to a breaker unless the breaker is explicitly identifies as having 100% rating (which i haven't seen one yet). so a 15A circuit is max loaded to 12A (way more than this light in question), and a 20A circuit is good to 16A (barely but all good).Since I don't do residential construction myself, i'm not 100% sure on this, but I believe our local codes have changed in the past few months to start pushing back towards using Armored Cabling or conduit for some of the wiring as we're now required to use Arc-Fault Circuit Interrupting Breakers in sleeping area related circuits. I was told that we're now required to have mechanically protected wiring up to the ARC fault device (which is usually a receptable - similar to a gfci outlet) and then downstream of that you can use standard non-metallic sheathed wire again.The devices that scare me are the wire nut replacements that are gaining traction here. they're a push-in style connector with 3, 4, or 6 wire connections but they're the same idea as the push in connector on a receptacle. Just a little sprung pin pressed against the wire. Put that in the welder test and see how it holds up. Sheesh. Plus almost every one I come across has bare copper sticking out the back of it, which is extra scary since 90% of my work is done energized.Click for Scary

author: Monkeh
author_rank: Super Contributor
timestamp: February 15, 2016, 05:36:34 pm
content: Quote from: Xplode on February 15, 2016, 04:35:41 pmAnd this is where I think the NEC is utterly stupid. Is it 20A or not? ... apparently not. Insanity.QuoteThey actually work very well. No copper is exposed unless people use them wrong (they have strip length markings!).They will go on the welder as well, I plan to chain assorted connectors and apply as much current as I can sustain (>120A easily), see if any connector becomes loose or heats significantly faster.

author: Xplode
author_rank: Contributor
timestamp: February 15, 2016, 06:50:06 pm
content: Quote from: Monkeh on February 15, 2016, 05:36:34 pmThe 80% rule doesn't mean the circuit can't handle 20A. It is fully rated to deliver 20A, but you may experience nuisance tripping, or faster wear due to running at 100% load all the time. How many people here would buy a power supply rated for 20A and run it at 20A all day and think that was a good idea and that it would be reliable and last forever? Not many I'd think. The goal of the breaker ratings is to protect the wire. Therefor the breaker will trip above 20A to prevent damage and a potential fire, it does not mean you should load the thing up to max capacity, nor does it offer protection for the end device being powered.The idea of the push-in style nut is ok, but in reality I see lots of problems. Even with the strip guide markings, the act of pushing the bundled wires back into the box cause the whole bundle to rotate slightly and this action will cause some wires to experience pressure into the device, and others to experience pull outward from the device. this outward force pulls the wire back out of the nut and exposes copper. Trust me, Push a bundle in and out of the box a couple times and you'll start to see copper. Its not a good product in my eyes. Plus, the tabs in the back of receptacles fail all the time due to heating issues, what makes these any different? They're produced just as cheaply.

author: Monkeh
author_rank: Super Contributor
timestamp: February 15, 2016, 07:01:31 pm
content: Quote from: Xplode on February 15, 2016, 06:50:06 pmIf it's only good for carrying 16A continuous, it's only good for 16A. You can pull a couple hundred amps through it for a short duration, so let's call it a 200A circuit.We do not have nuisance tripping or 'faster wear' by using a circuit to its nominal capacity.

author: Xplode
author_rank: Contributor
timestamp: February 16, 2016, 12:46:07 am
content: Quote from: Monkeh on February 15, 2016, 07:01:31 pmYou can have nuisance tripping. You've got 18amps plugged in running constantly, and then someone plugs in a 2A load with a bit of inrush, and bam you end up with a tripping breaker.The breaker does wear itself down when it opens under load. It draws an arc inside and wears at the contact points. Its obviously worse under a fault condition, but it still occurs if there's any load at all. Breakers that have been manually turned on/off lots, or experienced lots of tripping show up on thermal scans ahead of their less abused counterparts. This is often why.Circuit breakers are primarily heat based devices. Controller the thermal loading of a panel in a residential home is pretty difficult. I have to lower the ratings on every piece of electrical equipment if the temperature is known to be higher than 30C in the area due to this. Some homes are going to have air conditioning and it helps cool the panels while others are going to have the panel next to the furnace in a mechanical room where the temperature is 30C all day.Your option would be to say that this 16A rated circuit but it is ok to overload, sometimes... just be careful you know. since its really ok to pull 20A through it, but it probably won't trip until you're at least 125% OVERloaded... this sets a more dangerous precedent than saying "stay under the rating"There's clearly arguments to both sides of thinking, and i doubt we're going to change your opinion on how the circuit should be labelled, but I think it makes sense, and is safer for the general public, the way it is laid out now. Besides, that's the electrical code for the installer, not the end user. The end user can run 20A all day if they want, but they're probably going to experience tripping more often than their neighbor.If you really want to dig into the electrical codes It gets even more confusing when you start to look at the fact I can put a 50A breaker on a #12awg wire when I'm powering up a 20A motor load. I certainly wouldn't call it a 50A circuit, since the load is only around 20A once the motor is running, but it needs to survive that inrush current so its got a nice big breaker. and if the motor can't successfully start on that 50A breaker, I'm allowed to put a 60A on it. Still not going to call it a 60A circuit though. That's insanity.

author: Monkeh
author_rank: Super Contributor
timestamp: February 16, 2016, 12:55:45 am
content: Quote from: Xplode on February 16, 2016, 12:46:07 amNot a problem we regularly face, oddly..QuoteAnd that has nothing to do with loading to nominal rating. Either it's capable of handling it or it's not. Your breakers may suffer from being loaded to nominal and tripped; that's because they're only actually designed for 80%, and the label is, uh, optimistic. It's marketing bullshit, just like '20V' batteries for tools.Quote.. no, my option is to have a 16A circuit which can handle 16A continuous. No breaker trips magically exactly 0.1A above its rating. They have thermal and magnetic trip profiles, and all breakers in ROW are set to allow operation at nominal current. And cable is appropriately sized.QuoteBut it is a 60A circuit. Or at least 80% of one.Again, in ROW, we have breakers with trip profiles. They are selected according to the type of load, and the cabling used is calculated andtestedto ensure safe operation of the breaker over fault conditions.

author: Xplode
author_rank: Contributor
timestamp: February 16, 2016, 01:43:40 am
content: You keep implying that our breakers don't have trip profiles, but they obviously do. And they have Interrupt ratings in the 10kA to 100kA+ ranges so that they can operate safely in a fault situation (so long as available fault current was considered during product selection). None of this is really the question at hand.The trip profiles dictate that the breakers will trip once you go over the marked rating, same as I suspect yours do. if you're .1A over the rating its probably not going to trip since that's such a tiny amount over it could easily be lost in the manufacturing tolerances. However, it may after a while. It'll probably take a while, but it might. I'd call this nuisance tripping, since while it is technically overloaded, it isn't anywhere near dangerous and it certainly isn't a fault condition. However, this would all be avoided if you simply stayed under the breaker rating. Doesn't matter where you are in the world, if you stay under the rating it should never trip. Plus it gives you some wiggle room for loads that might fluctuate. Since breakers are thermal devices, having a row of breakers in a panel that are all operating at their max rated load increases the odds of a trip as well, altering that trip curve you keep talking about. If its the only breaker with a load on it, then it will be less likely to trip since the heat can dissipate through the electrical panel, bus bars, wiring and other breakers. Hence the ambient temperature rules I need to consider in warmer environments.We also have different types of breakers and fuses, each with their own operating characteristics and ideal use situations. My comments have been based on the generally used residential style thermal type breaker since that's what the original post was about (residential installation). In an industrial location I probably wouldn't be feeding a motor with a residential style breaker as usually they aren't HRC rated and the services are much larger. If I had to use a breaker with a big industrial load, I'd likely use a breaker with the ability to adjust the magnetic trip profile to prevent tripping on inrush. I was simply highlighting that there is lots of variations in the code rules, developed to allow an educated (hopefully) and trained person to maximize the installation and keep the costs reasonable without compromising safety. The 60A breaker mentioned does not make the circuit 60A capable in the eyes of the code (or any of the installers on this side of the pond). It would still be based off the calculated values of the wiring, minus any derating factors such as high ambient temperatures, conduit fill, and distance.It is interesting what you are saying about your 16A circuits delivering that all day without trouble. At what point do they start to trip when overloaded? I'm actually kind of curious to compare the trip curve graphs of the two now.

author: Monkeh
author_rank: Super Contributor
timestamp: February 16, 2016, 01:49:34 am
content: Quote from: Xplode on February 16, 2016, 01:43:40 amSo then how do you identify the actual current carrying capability of the circuit after the fact? Measure the conductors, inspect every inch of the installation? ... or just use a breaker with a nominal rating to match the circuit capability.Pretty much infinite.. and yes, a B16 can take 20A continuously. So can the wiring it's used with. Wiggle room: We build it in and get circuits which do what they say on the tin.E: For reference, 2.5mm² hardly even gets warm in open air at 60A for 40 seconds.

author: IanB
author_rank: Super Contributor
timestamp: February 16, 2016, 02:08:45 am
content: What is also not being mentioned is that circuits are often wired differently in the UK. For instance a standard UK socket is rated for 13 A at 240 V and thus can supply 13 x 240 = 3000 W continuously. Plenty of devices like electric kettles or space heaters are manufactured that consume exactly 3000 W, are fitted with a plug containing a 13 A fuse, and are expected run as long as you like without anything tripping. This works because the wiring behind the wall socket and the breaker in the panel are both rated for substantially more than 13 A. The fuse in the plug protects the appliance flex and the circuit is not close to its limit.Of course if you plug several 3000 W devices into the same circuit all at once then you may trip the breaker, but with a typical distribution of loads this doesn't happen (unless the WI is holding a social event and wants to brew cups of tea for 30 people all at once...)

author: Xplode
author_rank: Contributor
timestamp: February 16, 2016, 02:09:06 am
content: Quote from: Monkeh on February 16, 2016, 01:49:34 amAny electrician worth his salt is going to inspect the circuit installation if he intends to do any alterations to the breaker sizing anyway. So yes to the first part. It also means I don't need to run a large wire to the load just to get it through its startup. Since we're on opposite sides of that big ol ocean, I have to admit i'm not well versed in the mm² equivalents of our AWG sizing, but to run a 60A wire to my hypothetical motor load, versus a 20A wire (which actually carries a 30A rating for motor loading) there is a significant cost difference, not just in the actual copper wiring, but also in connectors, straps, etc. It all goes up. Its just not efficient use of resources to do that. So we are allowed by code to use a breaker of up to 250% the FLA rating on the circuit, regardless of the wire sizing. The wire sizing is a separate calculation (has to be >125% of the FLA to help accommodate the expected inrush). If that breaker can't support the motor getting through its startup, then I can go go up a size. This is simply to allow the trip curve to support the startup of the motor, but then still cover the wire in a fault situation (at which point the trip curve is near instant anyway, even without a magnetic element). So at the end of all that, there is no one here that would consider that circuit as rated at 50A or 60A, even though the breaker would technically allow it if you tried. On bigger motors in industrial locations, they're usually fed via a Dual-Element/Time Delay style fuse anyway. Then the sizing is lowered to 175% of the FLA rating.As for the trip curve graph you posted, I will have to try and dig up something from a local vendor this evening and post it up for comparison. It's dinner time here and I'm starving

author: IanB
author_rank: Super Contributor
timestamp: February 16, 2016, 02:14:39 am
content: Quote from: Xplode on February 16, 2016, 02:09:06 am2.5 mm² is about 13 AWG

author: Monkeh
author_rank: Super Contributor
timestamp: February 16, 2016, 02:20:59 am
content: Quote from: Xplode on February 16, 2016, 02:09:06 amWho said anything about altering the breaker? If it's got a 60A breaker, why should it not be able to have a 60A load? Why should it be allowed to have a cable so small a continuous 60A load from a fault could be a hazard?QuoteYou don't need to run a 60A wire. You need to run a wire capable of handling the prospective fault current until the chosen breaker is ensured to trip, without becoming hazardous.

author: Towger
author_rank: Super Contributor
timestamp: February 16, 2016, 04:17:29 am
content: So in the states you don't have different mcb/breaker types to handle higher inrush currents, you just use a much higher rated breaker?

author: Xplode
author_rank: Contributor
timestamp: February 16, 2016, 04:24:55 am
content: If you're not altering the circuit, why would you even ask about inspecting it? The motor loads are monitored at the motor starter for excessive loading that is specific to that motor's FLA (usually adjustable via interchangeable heating elements, or trim pot on electronic units). The only situation that should cause that breaker to trip is a fault, which it will have no problem handling since the current will jump drastically above the ratings and trip out the magnetic elements (assuming proper grounding, if the fault is ground related). The breakers are going to clear a fault before the wire can heat up to any dangerous level anyway, even with the increased time curve of the over sized breaker. So I think despite the circle we've gone in, we both are agreeing on the same underlying foundations for the safety of the installation design anyway.I dug up a manufacturers Time Current Curve graph (Siemans Residential Breakers) but its pdf, sorry couldn't find a jpg. This is a common breaker used currently in residential and commercial installations for general purpose circuits.It looks like your breakers don't trip when they're supposed to, which seems odd to me. If I'm reading that chart right, it looks like at 23A the B16 would take around an hour to trip out. That seems more dangerous to me than a breaker marked 20 that will trip out after 5-10 minutes. Why does it make sense to have a 16A breaker that doesn't actually function reasonably quickly once you're over that rating? Our wiring is apparently larger than yours from the sounds of it too (#12 is about 3.3mm²). So the North American 20A breaker can deliver the rated power, and is backed up by larger wiring for the fault currents that you mentioned, plus won't get as warm at the 23A in this example. (which is technically overcurrent in both setups). I will agree that to a homeowner, the faster tripping is far more inconvenient, but its not safer to let it run longer.There's too many differences in the way the power is distributed to probably say one is truly better than the other anyway. Especially since it sounds like you guys have different physical sized wiring available to you. I actually like the fact that you guys get higher voltages - lowers the line loss after all! But ours does hurt a little less when you do something stupid. But you guys get more horsepower per circuit... I've been curious about European power systems for a while, just never had the chance to really educate myself on it. One post a few back leads me to believe you guys have fuses right at the receptacles??? Also, since you guys use a grounded earth system (that right?), is it a 230V to earth setup with a Hot Line/Neutral/Ground configuration or a Line-to-Line with earth? And if its the first, do you have two Lines coming in for your services or just one? (ie 460v Line to Line?)

author: Xplode
author_rank: Contributor
timestamp: February 16, 2016, 04:33:24 am
content: Quote from: Towger on February 16, 2016, 04:17:29 amI'm in Canada, so I can't say for certainly how the US Electrical Code says it is to be done. But that's a complicated question.It depends entirely on the installation and surrounding factors like voltage available, horsepower requirements, etc.In a small operation, they may only have single phase power so its probably going to be a standard residential style breaker. So there aren't really multiple types to pick from, you just use what is certified for use the panel and the code allows us to go larger. The current draw is marked on the load, and since its not possible to just plug something extra in to the circuit, it is considered a calculated load and so a larger breaker isn't really a risk since the wire will never continually supply more than its rating. Fault currents are massively larger than the rating, so easily cause the trip elements to function quickly before the wires become dangerous.In a situation where three phase power is available, you may have choices on the types of breakers. When working in larger installations, we often have Motor Control Centers (MCCs) that allow us to rack in whatever type of circuit protection we need. This is usually only available at higher voltages like 460V or 600V (or higher) though, but in those cases, we can use motor rated CBs or Time-Delay Fuses.It really does come down to fault currents. In smaller voltages and currents the power required to be dissipated is significantly lower than at higher voltages and currents.

author: IanB
author_rank: Super Contributor
timestamp: February 16, 2016, 04:49:08 am
content: Quote from: Xplode on February 16, 2016, 04:24:55 amEurope varies widely in electrical systems. You have to look at each country separately.QuoteIn the UK appliance plugs have a replaceable fuse (the plug, not the socket). Most of the time it is a 13 A fuse, but some appliances like lamps will be fitted with a 3 A fuse.QuoteIn the UK the 240 V supply is Live/Neutral/Earth with 240 V on the Live relative to Neutral/Earth.The 240 V supply is almost invariably derived from a 415 V three phase transformer with each 240 V circuit made from one of the phases and the neutral. Most homes only receive one of the phases, but larger premises and commercial properties might get all three phases especially if they have large loads.The split phase arrangement found in North America is not found in the UK except on construction sites where electric tools are supplied by a 55-0-55 center ground supply.

author: Xplode
author_rank: Contributor
timestamp: February 16, 2016, 04:57:39 am
content: Interesting! Thanks for the details.So the tools are actually 110V tools, same as here? That's interesting. Any reason they aren't made to match the local standards? Seems like an inconvenience to have to wire up transformers for temporary power on construction sites.

author: IanB
author_rank: Super Contributor
timestamp: February 16, 2016, 05:17:03 am
content: Quote from: Xplode on February 16, 2016, 04:57:39 amThe tools thing is for safety since the maximum voltage to ground is 55 V, but this is only for commercial tools on construction sites. It's no inconvenience since such tools do match the local standards for that environment. The tools and transformers do not have to be specially made, they are standard items.Home use tools run off 240 V just like anything else though.

author: Xplode
author_rank: Contributor
timestamp: February 16, 2016, 05:36:52 am
content: Quote from: IanB on February 16, 2016, 05:17:03 amI guess I meant the local standards used everywhere other than the job site.Guess you can't take the tools home and use them then huh. That seems kind of annoying having to own multiple versions of the power tools, but I suppose that means you aren't required to use Ground Fault Detection circuits on the job site?

author: IanB
author_rank: Super Contributor
timestamp: February 16, 2016, 05:43:39 am
content: Quote from: Xplode on February 16, 2016, 05:36:52 amFrom what I've heard it's pretty easy to get hold of the 110 V transformers used for construction tools. Anyone who works in the trade has probably acquired one to keep at home if they have a need.

author: Monkeh
author_rank: Super Contributor
timestamp: February 16, 2016, 01:43:05 pm
content: Quote from: Xplode on February 16, 2016, 04:24:55 amThat is a short circuit, not a fault. Various other issues can cause excess current flow WITHOUT exceeding the breaker rating. Which is why the wire must be able to handle the current the breaker can sustain, indefinitely.QuoteThey trip when they're supposed to. A B16 (or a C16, or a D16) breaker supplies a circuit capable of handling a 16A load. All the time. It does not mean it will trip after 16A, it means it willhold16A. The wiring will remain safe if properly installed until the breaker trips.Your breakers are set to run permanently on the edge, and hot. Ours are set to handle their rated current 24/7/365 without serious heating or risk of nuisance tripping. They do what they say on the tin without funny business.. yours do 80% of what they say on the tin.QuoteBS1363 plugs are fused to 5, 10, or 13A (other sizes are available but non-standard) to allow operation on ring final circuits, which are rated for 30/32A (fuse or MCB). It's not an ideal situation, but it is what it is. Personally I prefer to use normal radial circuits, as they're easier to wire and cause less disruption in the event of a major fault (although tripping that B32 is hard! I have my ways, and welders, though.).It's 230V (nominal, usually closer to 240V in reality) phase to earth. Single phase and neutral. Some properties may have split phase (two 230V phase to earth lines, 460V phase to phase), but it's uncommon. Usually provided out in the sticks where no three-phase supply is available. This is basically never used phase-to-phase.In some areas, we can have three-phase (230V phase to earth, 400V phase to phase) in domestic properties. Very unusual except for very large buildings.

author: Cerebus
author_rank: Super Contributor
timestamp: February 17, 2016, 12:55:48 am
content: Quote from: Monkeh on February 16, 2016, 01:43:05 pmIt's probably worth a word of explanation on what a "ring final circuit" is as it's a peculiarly British thing. It's also colloquially referred to as a "ring main".The vast majority of AC outlets in a British domestic or office installation will be on ring mains. This is a 32A circuit that's wired in 2.5mm2copper (roughly #13 AWG for our 'murkin friends and Canadian cousins) that loops from the distribution board (aka fuse board) around the area it's serving and then back to the distribution board andbothends of the cable are terminatedtogetherthere - thus you have a continuous loop of copper from fuse/MCB to outlets and back again to the fuse/MCB. Current can flow both ways around the ring roughly halving the load on the cable or alternatively doubling the available current for the cable size. Basically it's a way of economising on the amount of copper you need.It was the common introduction of this that caused the move from 15A round pinned plugs to the now familiar 13A 'square' pinned UK plug that is individually fused at the plug. You don't want an appliance with a 6A IEC cord to have a 32A MCB as its only protection.I might also try and clarify an earlier comment about how UK sockets are physically wired. You can strip back the outer insulation on a short length of the ring, strip back about 3/4 of an inch of the individual conductor's insulation in the middle of that, fold the conductors over, twist and insert them into the terminals on the back of a socket and tighten the holding screws - leaving the ring physically as well as electrically unbroken. Thus reducing the risk of open circuits and in particular an open ground circuit.Another thing that leads to differences from other countries electrical installation practice is the prevalence of brick built properties in the UK*. It's quite common for electrical circuits to be buried inside walls in a way that makes them completely inaccessible for inspection or adjustment. Often this means that a ring main cable will come straight out of brick or plaster into an outlet's backbox. So UK practice dictates that any connections in cableswhere they cannot be directly inspectedmust be made by crimping, welding or other permanent means that can't work loose. Thus the exact place wire nuts are in common use in north america is exactly where they would be forbidden here. I don't know a single UK electrician who doesn't regard wire nuts as the work of the Devil and that may go some way as to explain why.Talking about wire nuts, one thing I've seen no mention of is vibration. I'd have thought that vibration would be very, very bad in the long term for wire nuts. Sure, screwed connections, as are common here, are vulnerable to vibration too, but I'd have thought much less so than wire nuts.*We used up all our forests building ships so we could go and fight the Spanish, the French and the upstarts in the British American colonies. No, really, there's a marked shift in construction from wood to brick when we literally cut down our forests to build a navy. That's why the Norwegians have to send us a decent sized Christmas Tree for Trafalgar** Square each year.**Yup, that Trafalgar - sorry France.

author: Cubdriver
author_rank: Unknown
timestamp: February 17, 2016, 01:33:46 am
content: Quote from: Cerebus on February 17, 2016, 12:55:48 amI'm not sure if 'directly inspected' might mean something different over there in the UK, but know that here in the US any splices must be accessible too - you can't make a splice then bury it behind drywall, or in concrete or a cavity in a block wall - it needs to be in a junction box, with a removable cover. Being able to access the splice (by removing a box cover, or a device such as a receptacle or switch in the box) is considered 'accessible' here, even if the box is in an attic. Would that be considered accessible for direct inspection there, too, or is it a more strict definition that you need to adhere to?I can't imagine a condition in which vibration in a home would cause a properly installed wire nut to work loose - if you crank them down correctly they're quite tight, and at the same time fairly small in mass, so I think they'd be inclined to move with the wires, by and large.

author: richard.cs
author_rank: Super Contributor
timestamp: February 17, 2016, 09:59:53 am
content: Quote from: Cerebus on February 17, 2016, 12:55:48 amWhile that is clearly possible I don't think I've ever actually seen it done. It is definitely more common to leave cut the cable and then terminate both cut ends (+ 1 spur cable if required) into the terminals. Something like this:Quote from: Cubdriver on February 17, 2016, 01:33:46 amI suspect what he was meaning here was that with our shallow back boxes (in masonry walls at least) there's not a lot of room for any additional splices. Standard box depths are 25, 35 and 47 mm with 25 being very tight for sockets (need to dress the wires nicely, no space for anything extra), 35 being very common, and 47 being too great a fraction of a brick thickness to be used very often (but common in drywall, etc). Hence his assumption that they would end up buried in the wall or something.QuoteHistorically we has "screwits" which were basically a ceramic wire nut. Associated problems were over-tightening so the wire was twisted almost to breaking point and thinned at the base of the twist, under tightening resulting in loose connections that got worse over time with thermal cycling, and the ceramic end falling off exposing live parts. Junction boxes with screw terminals replaced them:with "chocolate block" used for inline connections inside backboxes (but sometimes considered a bit ugly and an example of poor workmanship):The modern way uses Wagos, which being spring loaded put constant force on the conductor and can't work loose over time. Testing shows these are much more reliable than screw terminals but many electricians still don't fully trust them.

author: forrestc
author_rank: Unknown
timestamp: February 17, 2016, 11:41:41 am
content: Quote from: richard.cs on February 17, 2016, 09:59:53 amOh, NOW things make more sense.The most common device box currently in use in new construction in the US is ~70mm deep. You can get smaller ones, but they aren't very popular, mainly because they're more expensive than the 70mm deep ones. All of the wire nuts and splicing gets folded into the back of the box and you end up with lots of room in the front of the box for the device. When I do new work, I always use the larger ones which are roughly 89mm deep. They fit perfectly between the two sheets of drywall and leave lots of room inside for wiring.There are numerous rules for how many wires and devices can be legally installed in a box. Without going into details, there are only so many conductors which you can put in a box, and the quantity varies on size of the conductors. It is all engineered to prevent issues with too many wires being crammed in a box (overheating, damaging wires, etc).There are *no* buried joints. Wire nuts are in the boxes. No splices are permitted in buildings where they aren't accessible. If there are buried splices in UK wiring, that really scares me regardless of the type. The US method is to use unbroken copper between the boxes, and splices only within the boxes in ALL circumstances. The boxes are designed to contain most electrical events.I can see how someone from the UK would look at our system and be scared, coming from a background as described.

author: richard.cs
author_rank: Super Contributor
timestamp: February 17, 2016, 12:37:21 pm
content: Quote from: forrestc on February 17, 2016, 11:41:41 am"Buried" joints are permitted here if of a suitable maintenance free type (e.g. crimps if suitable for the type of cable and made with the proper tool or constant-force spring terminals). They would still normally be in some kind of enclosure but that enclosure is not required to be accessible and is permitted to be partially or completely formed of the building fabric if that is non-combustible.In the past screw terminal junction boxes were routinely used under floorboards despite the requirement for screw terminals to be accessible for maintenance. It was considered acceptable to have to lift a board to access such junction boxes for inspection (check for tightness, etc) but with the advent of laminate floors in many cases it's no longer practical. The preferred option under floors is now something like this:So long as the connectors themselves meet the relevant standards for "maintenance free". This is usually the case but sometimes they have a lower current rating if used as such (to ensure a longer service life).Given the greater difficulty in replacing cables in masonry construction it's perhaps expected that joins in cables are considered more acceptable.

author: Gyro
author_rank: Super Contributor
timestamp: February 17, 2016, 01:22:23 pm
content: Quote from: Monkeh on February 16, 2016, 01:43:05 pmMinor correction... Default BS1363 plug fuses are 3A, 5A and 13A.

author: Monkeh
author_rank: Super Contributor
timestamp: February 17, 2016, 01:50:13 pm
content: Quote from: Gyro on February 17, 2016, 01:22:23 pmQuite right, sorry.

author: Cerebus
author_rank: Super Contributor
timestamp: February 17, 2016, 02:37:59 pm
content: Quote from: Cubdriver on February 17, 2016, 01:33:46 am'Directly inspected' meaning you can pop a cover off, look at it and tighten some screws if need be. Iwastalking about hiding away a splice or junction where you couldn't go back to it. It's not common, but sometimes there's no practicable alternative. Standard practice is to use crimps, sometimes in a crimped outer sleeving that's filled with petroleum jelly for environmental protection.Also there's some special cases like MICC where crimping forms part of the standard method of terminating the cable to a putty filled gland.The thoughts about vibration and wire nuts are a 'what if'. One place you'll find some serious vibration in a domestic setting is by a washing machine - certainly enough to be a concern for long term reliability of any nearby outlets and associated wiring.I'm trying to keep an open mind about wire nuts and not condemn US standard practice, even though instinct tells me they're evil. In the UK slang for shoddy workmen, especially tradesmen like builders, plumbers and electricians is "cowboys", as in "That looks like it was done by a bunch of cowboys". Make of that what you will. I'm not making any implication, just reporting standard Queen's English "as she is spoke".

author: Cerebus
author_rank: Super Contributor
timestamp: February 17, 2016, 02:45:55 pm
content: Quote from: richard.cs on February 17, 2016, 09:59:53 amOhh, not an assumption. Seen all too often in practice. I supplemented my income at University working as an electrician's mate. I've seen a few nice tidy logical electrical installations (mostly industrial), a lot of so-so ones where the rules were met but you wouldn't be proud to have been responsible (mostly domestic) and more horrors than I care to remember (anywhere). Most of the latter where where a builder thought he was up to doing the electrics as well.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 17, 2016, 06:46:38 pm
content: The trouble with aluminum wires is not so much the higher thermal expansion, but surface oxide and the very soft nature of the wires. So the wires just can't stand a high force, that is needed to give a reasonable contract with the oxidized surface.

author: Towger
author_rank: Super Contributor
timestamp: February 17, 2016, 07:14:34 pm
content: Quote from: richard.cs on February 17, 2016, 12:37:21 pmAFAIK Joins are to be avoided, unless there is no other option. If you think about it there is no need for a junction box in a standard new house wire. All joins are loops in and out at fittings. The irish standards are much the same, but have diverged over the years. The main difference is we tend to use 20A radials rather than 32A rings.