Not dying in a house with no ground - Page 1
Forum section: electronics / beginners

author: Popoe29
author_rank: Newbie
timestamp: February 20, 2018, 08:25:46 am
content: hey everyoneI just got a old oscilloscope off ebay the other day to learn the art of scoping. I have been watching a few videos on scopes to get frimlier with them when I came across dave's video how not to blow up your oscilloscope. and after reading a little bit it seems the earth referenced ground is pretty important to both measurements and safety. Only issue is my home has no grounding. Its a fuse box era apartment building with no ground in the outlets and no ground in the box. I cant cut into the wall to run any grounding. I read that a GFCI can be used as a alternative to grounding. What do you guys thank about this? would a GFCI keep me from frying my self or my gear and would a scope measure accurately if connected to a GFCI?Aslo another question along those lines would a GFCI coupled with a surge protector offer any protection to electronics. I have often worried about my toys being plugged in a ungrounded surge protector during a stormThanks

author: Mr. Scram
author_rank: Super Contributor
timestamp: February 20, 2018, 08:31:39 am
content: Quote from: Popoe29 on February 20, 2018, 08:25:46 amIsn't your landlord required to install any grounding? It seems rather dangerous to run certain kinds of equipment without any ground at all, like most appliances in the kitchen or bathroom.

author: Popoe29
author_rank: Newbie
timestamp: February 20, 2018, 08:39:47 am
content: I thought so too but the landlord isn't quick to fixing anything ive been waiting two months on a radiator that doesn't heat but the rents cheap and its close to work so its not to bad

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 20, 2018, 08:54:08 am
content: "Cheap, might die, 5/7 would rent again"Give or take if the landlord would be bankrupted by the expense, but a convenient anonymous report to the fire department might be appropriate here.As for instruments, it works the same as "lifted ground". On the one hand, you may not need an isolation transformer. On the other, you have nowhere for fault currents to go in case you do miswire something.Tim

author: Mr. Scram
author_rank: Super Contributor
timestamp: February 20, 2018, 08:59:58 am
content: Quote from: Popoe29 on February 20, 2018, 08:39:47 amI'm far from an expert on US law, but wouldn't the right to a habitable home include wiring that's remotely modern and up to code? Just the possibility of liability on his side if anything were to happen to you should be reason for him to act. I don't think Texas is known for its lenient penal system.http://realestate.findlaw.com/landlord-tenant-law/landlords-duties-regarding-repairs-maintenance-and-to-provide.html

author: Vic20
author_rank: Contributor
timestamp: February 20, 2018, 09:15:23 am
content: Quote from: Popoe29 on February 20, 2018, 08:25:46 amThe GFCI is not an alternative to grounding. In fact, having grounding and not GFCI is quite dangerous.If you only have one of them, I think it is best to have GFCI.The GFCI basically measures the current that enters the house on the live line and the current that returns in the neutral. If a difference of, for instance 20mA, is detected, it means that some current is returnig on a non intended way, like form your body to the floor, and it shuts down the power.It don't always protect you if you touch the live and the neutral at the same time but gives some protection if you touch only the live wires.The Ground wiring basically makes that any dangerous fault will generate a current that goes to the earth conductor tripping the GFCI.If you have grounding and no GFCI, the current on a fault appliance can happily return at high levels on the earth cabling. Such things can easily generate a fire.Moreover, if you ground yourself for ESD protection and touch a live wire, it can kill you if there is no GFCI.If you don't have a GFCI I will recommend to install it ASAP as it can save your life.I my house I have GFCI and no earth ground cabling.It is quite nasty because some AC current can couple with external metal appliance surfaces and induce current on you below the 20mA GFCI tripping point, but much better that having no GFCI at all.

author: paulca
author_rank: Super Contributor
timestamp: February 20, 2018, 09:34:48 am
content: Quote from: Vic20 on February 20, 2018, 09:15:23 amDo American's not put fuses into anything?Every plug is fused in the UK, whether it has an Earth or not. Further each circuit on the mains is fused at the fuse box. In addition (some times instead of fuse) there are RCD trips.

author: Vic20
author_rank: Contributor
timestamp: February 20, 2018, 09:43:02 am
content: Quote from: paulca on February 20, 2018, 09:34:48 amFuses protect appliaces, not people.A 1 amp fuese hardly protect a person that can be killed wit 100 mA.QuoteThe fuses in the UK sockets prevent a high current to burn the wiring and start a fire. They also don't protect from direct electric hazards. Only indirect damage by fire.If you want a minimum protection for you, you need something that trips at about 20mA. No fuse serves this purpose.In the case of having ground and no GFCI, a stray 1 amp current on the isolation that goes to ground can generate a fire and not trip any fuse. It all depends on the appliance and the fault mode.

author: Ian.M
author_rank: Super Contributor
timestamp: February 20, 2018, 10:08:49 am
content: Its possibly unsafe for you and definitely unsafe for the devices you are working on to use a bench full of test equipment powered from an ungrounded outlet. If you feed the bench through a GFCI, it significantly reduces the risk to you but does nothing to protect the devices you are working on against getting zapped by stray leakage currents that were supposed (by the design of the test equipment) to go to a proper grounding conductor connected to a true ground.If you attempt to alleviate the problem by grounding your test bench to a water pipe, any line to ground fault in the equipment on your bench or the D.U.T. may make some or all of the plumbing live, possibly affecting other apartments in the building. All it takes is a plumbing repair done with a length of plastic pipe, or a galvanically isolated anti-corrosion coupling upstream of your waterpipe 'ground' and the result is unsafe.DO NOT ADD GROUNDING EXCEPT IN COMPLIANCE WITH NEC 2014 !!!The only option short of rewiring the apartment is to use an isolating transformer to feed your whole bench. Its secondary side should have 'ground' bonded to Neutral, and Line and Neutral should be GFCI protected downstream of this bond. You can then ground your bench to a waterpipe for ESD prevention and to reduce EMI without causing a hazard to other apartments, but you must *NEVER* use any other outlet to feed stuff on connected to your bench, bypassing the isolation transformer. However a hazard exists if anything on your bench has a fault from Line to a true ground that is not bonded to your bench ground (e.g. possibly grounded data, telecom, satellite or CATV wiring), so don't have a wired phone on your bench, use WiFi for any bench computer, and use isolators that break the ground for any exterior antennae or CATV feed.

author: Insatman
author_rank: Frequent Contributor
timestamp: February 20, 2018, 10:19:20 am
content: Hi...I live in the Philippines and almost all homes here have no ground. The power company simply gives you two wires, 220ish VAC, 60Hz. I say 220ish...because it has varied from about 260 in the middle of the night to as low as 175 during the peak hours. To combat the voltage variation I have a 10kW whole house AVR which is a servo controlled variac basically. To deal with the lack of ground in my electronics workshop I have done two things. First I drilled a hole in the concrete floor and drove a galvanized steel ground rod in as far as I could. The ground of my AC outlets are connected to this in my workshop. This stopped the "tingling" I'd get from various electronic metal enclosures. 2nd, the very first project for my workshop was a 1KW isolation transformer for all incoming power for my bench. These two things thus far, plus just being careful, thinking twice before acting, and using decent test leads has worked to keep me safe.

author: Popoe29
author_rank: Newbie
timestamp: February 20, 2018, 10:25:13 am
content: Insatman did just give me a ideal. right out side my window is the power pole that supply the buildings right here theres likely a ground rod at the base. What do yall thank of me just grounding the outlets in my shop to that rod?

author: Mr. Scram
author_rank: Super Contributor
timestamp: February 20, 2018, 10:28:47 am
content: Quote from: Popoe29 on February 20, 2018, 10:25:13 amThat works just fine if you're the one causing a short to ground, but what happens when something else does that for you. Especially when that's HV?

author: Insatman
author_rank: Frequent Contributor
timestamp: February 20, 2018, 10:31:31 am
content: Quote from: Popoe29 on February 20, 2018, 10:25:13 amIn the US, you should measure about 120VAC from the hot lead to that ground. PLEASE use a decent meter for this and be very careful. From Neutral you should measure only a few volts AC. I suggest you do this measurement because in a lot of older homes in the US, Hot and neutral are reversed in some outlets. Once you have figured out which is which, then yes grounding to that rod is a good idea. I also strongly advise you get an isolation transformer for your setup. I bought a bare transformer from DigiKey, but you can likely find one used for much less. This might save your life when you make a mistake with live AC.

author: Insatman
author_rank: Frequent Contributor
timestamp: February 20, 2018, 10:32:36 am
content: Quote from: Mr. Scram on February 20, 2018, 10:28:47 amHmm...you have a good point. Having a separate ground rod is a better idea

author: Ian.M
author_rank: Super Contributor
timestamp: February 20, 2018, 10:46:58 am
content: N.B. Feeding your whole bench from an isolation transformer so you can ground your bench, and so you can tie secondary side Neutral to Ground so downstream GFCIs work, *DOES* *NOT* protect you from dangerous mistakes like touching a live conductor on your bench (although a GFCI after the isolating transformer will offer you some protection). Also an isolation transformer renders all upstream GFCIs ineffective downstream of itIf you need isolation for a D.U.T (e.g. to scope a SWMPSU without a differential probe), you should use another isolating transformer, downstream of the one feeding your bench. Caution: this defeats any GFCI protection for the D.U.T.

author: Insatman
author_rank: Frequent Contributor
timestamp: February 20, 2018, 10:57:10 am
content: Quote from: Ian.M on February 20, 2018, 10:46:58 amAgreed

author: Popoe29
author_rank: Newbie
timestamp: February 20, 2018, 10:59:03 am
content: What about having all the outlets grounded to there own rod outside and replaced with GFCIs. then having a isolation transformer and having the output of the transform wired to a GFCI in a enclosure? then with common sense and careful probeing me and my scope should be safe right?

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 20, 2018, 11:00:13 am
content: if legislation, the landlord and anything else failed... make your own ground in the floor level poking in copper rod inside the drilled floor and start making proper wiring throughout the house, GFCI and all. i will anticipate a debate for this, people may argue on concrete conductivity, effectiveness etc. but just think how are you going to be safe touching hot wire by tripping GFCI while ground is several meters down on earth while you are standing several meters up on a concrete structure? but that is just me, and as i said, if anything else failed. its your ghost anyway and your ghost belong to you remember that.edit: as a teaser, a home thats several KV away...

author: Insatman
author_rank: Frequent Contributor
timestamp: February 20, 2018, 11:04:04 am
content: Quote from: Popoe29 on February 20, 2018, 10:59:03 amI worry about a lighting strike or similar high voltage event that raises your pole ground rod to dangerous levels. I would recommend your own ground rod. Copper or brass is great if you can get it. I used steel because I had one...knowing it will corrode in a few years probably and need replacing.

author: danadak
author_rank: Super Contributor
timestamp: February 20, 2018, 11:53:14 am
content: Some ref material -https://www.tek.com/document/technical-brief/floating-oscilloscope-measurements-and-operator-protectionhttp://in.tek.com/dl/3AW_19134_2_MR_Letter.pdfRegards, Dana.

author: drussell
author_rank: Super Contributor
timestamp: February 20, 2018, 02:10:31 pm
content: Quote from: Popoe29 on February 20, 2018, 08:25:46 amYes, a GFCI is the proper solution to wanting to plug in a 3-prong grounding-type device when no ground is present in the device box. This is plainly spelled out inArticle 406of the USNational Electrical Code, specificallyArticle 406.3.Essentially, when you wish to replace a receptacle that is wired from a 2-wire, non-grounded cable, you have three options. Option one is to replace the receptacle with a new two-prong outlet. These are still produced for replacement purposes in this situation and will be of the polarized type. This obviously doesn't help your situation.The second solution is to replace the two-prong receptacle with a three-prong GFCI receptacle, provided it has been marked "No Equipment Ground." In addition, any receptacles downstream from the device box where the GFCI is installed (and properly connected to the outputLOADterminals) may also optionally be replaced with a 3-prong receptacle, provided they are each marked "GFCI Protected" in addition to "No Equipment Ground." This is usually done by replacing the first receptacle on the circuit with the GFCI and then updating all the rest of the outlets on that circuit downstream to the 3-prong type, properly marked. GFCI receptacles sold in Canada and the US should include 12 little stickers in the box, usually shiny silver color, that say "GFCI Protected" to stick on downstream outlets, where used, and sometimes ones with "No Equipment Ground" just for this purpose since this is a common issue. Alternatively, instead of a GFCI first receptacle, you can install a GFCI breaker for that circuit and then label the replaced outlets accordingly. GFCI receptacles are usually about 1/5th the cost of a GFCI breaker, though, so that method is rarely chosen.(Doesn't help you with your fuses, regardless...)The third method is to add a bonding (code-speak forgrounding...bondingto ground) wire to the device box. This can mean replacing the 2-wire cable with modern 3-wire cable or simply fishing in a ground wire. The wire must go to a main premise ground that meets current electrical code. Depending on the location and soil type, etc. this means grounding rod(s) and/or the service entrance of the water main if supplied by underground copper, etc. That needs to be determined by your local inspector. Generally if you're going to need to upgrade your bonding your inspector is going to require service equipment updating to current code as well, which is what likely tends to cause building owners to not want to ever update anything. One can always try pleading with your local inspector, of course.Under no circumstances may you ever use one of those three-prong to two-prong adapters when there is no ground present in the device box. Those are only used where the box and two-prong receptacle are grounded (so the faceplate screw is ground) and the little tab is properly mounted with the faceplate screw. They are silly because in this case you should just replace the 2-prong with a standard 3-prong grounded outlet, since the ground is there.QuoteUnder most circumstances, yes, though the noise margins may be worse on some measurements due to the lack of grounded shielding. It really depends on what you're measuring but I doubt you'll be looking at anything like tiny RF signals as a beginner. My first oscilliscope, an ancient ~5 MHz tube model, doesn't even have a grounded plug. It still works fine, you just have to remember that you can accidentally enliven the chassis of a floating scope if your GND lead goes somewhere that has a path back to mains.Quote from: Mr. Scram on February 20, 2018, 08:31:39 amNo, if it passed electrical code when it was built (which it did), it is not required to be updated unless you are doing renovations and open the wall, in which case it is required to be updated to the standards set out in the current code when work is done. Also, if a receptacle is added to an existing circuit where a receptacle did not exist before, thenewreceptacle must be properly grounded and bonded to earth (but you do not necessarily need to re-do the other receptacles on the circuit, unless you're opening walls.)Quote from: T3sl4co1l on February 20, 2018, 08:54:08 amThere is no requirement for it to be updated unless other renovation work is being performed which opens the wall. Then it would need to be updated. Calling anyone isn't going to help, it is a perfectly valid installation.QuoteNowhere for fault currents to go means you'll be less likely to blow up your scope with careless misplacement of the ground lead.Seriously though, it is perfectly safe. If the GFCI sees more than 5 mA of current flowing outside the closed loop, it will trip. That is barely enough to feel a slight tingle. This could be a nuisance if you accidentally trip things all the time on the bench (I would personally find a GFCI very annoying on my test bench) but it is completely safe. Apart from the shielding and noise shunting/protection aspects, really the only drawback of not actually having the ground is that a faulty piece of equipment, with an internal fault that causes the chassis to become shorted to line, for example, will not immediately blow the overcurrent fuse. You would have to touch the chassis to something that is actually grounded (perhaps you) and cause the 5 mA of current to flow and trip the GFCI instead.From a safety standpoint of not zapping yourself, a GFCI is far more important than a good ground.Quote from: Mr. Scram on February 20, 2018, 08:59:58 amAs long as it passed inspection when it was installed and has not been improperly altered since, it is perfectly valid. It would be silly to require mandatory upgrades. Where does it end? Everyone has to re-wire their house every four years to stay up to date with the code? Should all dwellings be forced to go back and install arc-fault breakers for any circuit feeding a bedroom? Kitchens be gutted and re-wired for split-duplex where only single-circuit outlets are installed? Not going to happen. That would be silly.Quote from: Vic20 on February 20, 2018, 09:15:23 amHyperbole much?No, GFCI is not the same as grounding. They serve different purposes, though from a safety standpoint there is some overlap. In the US and Canada, a GFCI branch circuitisa valid way of using three-prong, grounding type equipment on an ungrounded installation. You just need to be aware of the limitations, like lack of grounded equipment shielding, which is why the individual outlets must be properly marked accordingly.The US and Canada do not have silly RCDs on whole premise wiring. We aren't all dropping like flies from getting electrocuted. Quite the opposite. The current methods have been found to be sufficiently safe. Local GFCI protection is required in potentially damp locations like right beside a kitchen or bathroom sink, outdoor outlets, spas, etc. and I personally believe that is sufficient, though a paranoid person could "upgrade" if they really wanted.Whole-premise RCD protection would be a nightmare for me, personally.QuoteFor not getting zapped? Absolutely.QuoteRegular branch circuit GFCI outlets in US/Canada are 5 mA trip.QuoteIt doesn't give youANYprotection against touching both at the same time!QuoteNow you're just making stuff up. The ground conductor must be sized to handle the fault current of the live conductors. It would be rather pointless to have a 14ga bond wire on an 0/4 feeder.QuoteThat's a bit of a stretch...That is why wrist straps have a 1 meg resistor in them.QuoteAlright, we get it. You like GFCIs and hyperbole.Got it.QuoteDude, it sounds like you have some faulty appliances. You should check into that.Quote from: paulca on February 20, 2018, 09:34:48 amThis has nothing to do with fuses...QuoteYeah, that's because you folks use the strange-to-us method of essentially stiffly connecting the whole house directly to the mains feeders and letting the plugs try to play mediator.Your system seems insane to us, and our system seems insane to you, but they both work.

author: Mr. Scram
author_rank: Super Contributor
timestamp: February 20, 2018, 02:20:59 pm
content: I don't think "it was up to code in 1924" will cut it when someone dies due to your lack of maintenance. But then again, regulations don't always make sense.

author: drussell
author_rank: Super Contributor
timestamp: February 20, 2018, 02:43:36 pm
content: Quote from: Mr. Scram on February 20, 2018, 02:20:59 pmThis has nothing to do with maintenance. Obviously if your installation is deficient somehow, broken plugs, exposed wiring, etc. and it kills someone somehow, that is going to be negligence.If the wiring which was installed is still sound and fit for service, there is no issue, even if it was installed and inspected in 1924. Whoever is insuring the place against fire, though, is likely to want some electrical upgrades over the years to maintain reasonably-priced insurance coverage. That's who usually ends up forcing the owner to update. Well, that, or doing any kind of serious renovations.Bringing in a new safety standard just means that new stuff must conform, so eventually old gets rotated out and new rotated in over time to whatever is considered best practice at the time and thus is current minimum code.It is somewhat strange for his apartment to have no grounding as generally even very old commercial buildings and most larger apartment complexes, etc. would have had grounding but it probably wasn't required for that particular size of residential. Commercial probably required conduit at the time, so would be grounded, but obviously not his particular residence type.

author: Mr. Scram
author_rank: Super Contributor
timestamp: February 20, 2018, 03:03:19 pm
content: Quote from: drussell on February 20, 2018, 02:43:36 pmYou're Canadian and we're talking about US code. Do you have experience with US code or are you extrapolating what you know about local code to the US? These things can and will vary wildly across borders.And again, I doubt you'll get off the hook when someone kills himself using an installation that's considered a death trap by today's standards. Even if that was up to code nearly a century ago. We're not even talking about things breaking and wearing over time.

author: drussell
author_rank: Super Contributor
timestamp: February 20, 2018, 03:27:14 pm
content: Quote from: Mr. Scram on February 20, 2018, 03:03:19 pmMost parts of the Canadian and US code are very similar, though certainly not identical. I am well aware of the differences, as we build things like three-phase power converters that are intended for operation in both countries.The code which I cited is part of the US, not Canadian NEC. US NECArticle 406.3, is the authority on this, not me. You may wish to read it for yourself, if you like.QuoteAgain, I refer you to your friendly neighborhood codebook. Non-grounded 2-wire was still valid for new installations much more recently than 100 years ago and is still referenced many times in the current code since it is still in active use in the field. Code tells you exactly how to deal with it and also contains all the information about responsibilities for the legalities, etc. for electrical installations.Plus, I certainly wouldn't call 2-wire un-grounded "a death trap" when properly implemented. As long as somebody doesn't go around doing something like putting 3-prong outlets in there with no ground, no GFCI protection, etc. it is all still perfectly safe from a "zap yourself" perspective. Many appliances and devices are still supplied with only 2-prong cords because they are double insulated or transformer operated, etc. There is often no need for ground protection.If you're interested in this stuff and how it differs from your local code, read the US (and/or Canadian) NEC... It has all the information you seek.

author: JoeO
author_rank: Frequent Contributor
timestamp: February 20, 2018, 04:25:35 pm
content: Quote from: paulca on February 20, 2018, 09:34:48 amNo, we don't fuse anything. It saves on costs.

author: rsjsouza
author_rank: Super Contributor
timestamp: February 20, 2018, 04:40:24 pm
content: I am familiar with the NEC (although not a professional in the area) and know that drussell's points are sound. A grandfathered electrical installation does not make you liable if there are no explicit problems with it - something quite unusual to happen, given that 100 year-old houses are almost guaranteed to have had major renovations at a certain point in their lifetime.Regarding the problem at hand; I have lived most of my life in an apartment building without ground (the feeder was a three-phase 380/220) and the rare occasions I was shocked by an appliance it was entirely its fault (also by my electronic experiences, but that was entirely my fault) - therefore, it is not a "death trap" or anything of the sorts if it is well maintained.As for grounding your house on the feeder installation: you can't guarantee it won't be disconnected at a sudden if the maintenance crews need to work on it (not to mention it may be illegal, but I don't know the details). Also, as others have mentioned, you are connecting your ground to a system much more exposed to HV faults or electric discharges, which can raise the voltages to dangerous levels. I have seen this happen and obliterate electronic equipments (Audio equipment, TVs, VCRs...) in entire neighbourhoods - usually other appliances (fans, lamps, blenders, etc.) are much more resilient to these.As for fuses and circuit breakers: they are usually dimensioned to protect the wiring against overheat, not the person or the appliance.Quote from: drussell on February 20, 2018, 02:10:31 pmI don't quite get that: do you mean that in UK there is no main circuit breaker box?

author: Nusa
author_rank: Super Contributor
timestamp: February 20, 2018, 04:50:51 pm
content: In the US, ungrounded three-prong outlets are NOT legal (other than GFCI installations as mentioned above), although in practice you run across them all the time in older housing. If that's the case you CAN force the issue with your landlord. The most likely end result is they'll revert any 3-prong outlets back to 2-prong outlets rather than rewiring, which satisfies the law but makes it less convenient to use. You don't get what you really want, and a rent increase may be in your future.As for the power-pole ground, if it's utility owned, don't even think about it. They will not react well when they notice it. Drive your own grounding rod if you go that route.

author: helius
author_rank: Super Contributor
timestamp: February 20, 2018, 05:16:30 pm
content: Older US houses, before the grounded NEMA 5 connectors introduced in the 1960s, it was still typical for the fuse box itself to be grounded to multiple points including the service neutral, the cold water main, and a local grounding rod. At the time, metal armored "BX" electrical cabling was widely used for its safety and strength, which connected the fuse box to outlet enclosures in the walls.These grounding provisions were used on almost all houses because they were required for reliable phone service—a lightning arrestor in the telco network interface provides a path from the copper loop to local ground. As 3-prong NEMA 5 connectors on appliances became the norm, plug adapters for older NEMA 1 outlets in grounded box enclosures were sold to be able to use them without rewiring the house or the appliance. They are green rubber plugs with a grounding wire attached, which is screwed into the body of the outlet, and thereby grounded to the enclosure.

author: paulca
author_rank: Super Contributor
timestamp: February 22, 2018, 08:16:31 am
content: Quote from: rsjsouza on February 20, 2018, 04:40:24 pmYea. We have lots of fuses. Plugs have fuses, fixed installation points (washing machines, etc.) have fuses, each mains circuit (downstairs plug ring, upstairs plug ring, downstairs lights, upstairs lights, cooker, shower, etc. etc.) have a individual fuse (and an optional trip), then you have the mains fuse, usually 100A. If you blow that the electric utility people have to change it and there is usually a fine if you overloaded it.Yes these protect the wiring not the person (with the exception of the very common and probably mandatory on new installations RCD trip).Still it's much easier to replace a fuse in a plug than the meter box. Besides. A 15A fault current will not blow a 30A plug ring fuse, but it will set fire to the 3A mains lead to the device.Having individually fused circuits means if you want to work on a downstairs light fitting you can pull the fuse and put it in your pocket while leaving the remainder of the power on.

author: Ian.M
author_rank: Super Contributor
timestamp: February 22, 2018, 08:51:42 am
content: The days of distribution panels with plug in fuses (or even plug in breakers) in the UK are mostly long gone. The formerly common old Wilex panels with either cartridge or rewirable fuses or with retrofitted breakers, a wooden frame and an open back aren't permitted under current IEE Wiring Regulations (UK equivalent to US NEC) and although some units protected by a 60A utility company fuse may be grandfathered in, any rewiring work is likely to require their replacement. Newer metal or flame retardant plastic backed Wilex breaker panels are still compliant but IIRC there aren't any pluggable RCBOs for them so RCD protection cant be retrofitted at the panel.Extreme caution should be used if investigating other brands of old distribution panels with rewirable fuses as some used friable asbestos cloth in the rewirable fuse carrier. Removal by a specialist Asbestos remediation company followed by compete replacement is probably cheaper than replacing individual fuses with cartridge fuse carriers (if compatible ones are available) and cleaning the Asbestos residue from the existing panel.The current practice in UK consumer units seems to be DIN rail based breakers +one or more RCBs feeding them or individual RCBOs. There is no way to physically disconnect *and* isolate a circuit without tools, (though you could trip a breaker use an appropriate lockout/tagout device to secure it in the OFF position) and actually pulling a breaker rather than disconnecting its load circuit cabling would leave the tag of the live busbar feeding it exposed.

author: paulca
author_rank: Super Contributor
timestamp: February 22, 2018, 09:27:07 am
content: Quote from: Ian.M on February 22, 2018, 08:51:42 amI worked as a sparks mate many, many years ago and this would be quite worrying. When you enter a new property that has the power on to do some work but there is a fuse pulled, sitting on top of the consumer unit it would be all too tempting to simply plug it back in. Immediately killing the guy working in the attic.We were always told in such a situation to walk round the whole house shouting your intent to put the fuse back in. We were also told when we wanted to pull a fuse to do work to put the fuse in our pocket so it can't be replaced by someone while you are working.What is stopping someone simply thinking the breaker was left off by the last person and flipping it back on? Unless there is a key, even a plastic keyed tool that you can take with you.I suppose an alternative is to put a sticker on the breaker saying "DO NOT ENERGIZE".

author: Ian.M
author_rank: Super Contributor
timestamp: February 22, 2018, 09:54:18 am
content: That's why you need the correct lockout/tagout device for the breaker if you are working on the circuit as a professional. As an amateur without the manufacturer's lockout/tagout device, or as a professional without the right lockout/tagout device - if you cant secure the consumer unit, you'll have to disconnect its load circuit at the breaker and tape up the wire end(s) so they cant make contact, then replace the consumer unit cover.A 'DO NOT ENERGISE' sticker without physically disconnecting the circuit is only appropriate if all other people with *ANY* access are qualified and you trust them 100% - 'with your wife and your life' level of trust, and the HSE will throw a fit if anything goes wrong.

author: rsjsouza
author_rank: Super Contributor
timestamp: February 22, 2018, 12:35:45 pm
content: Quote from: paulca on February 22, 2018, 08:16:31 amQuite interesting; thanks for the clarification.About your last point, though: in a light fixture, is the fuse on the fixture or in the wiring that leads to it? If it is in the fixture, how do you replace the fixture itself without disconnecting the whole house?

author: paulca
author_rank: Super Contributor
timestamp: February 22, 2018, 12:56:40 pm
content: Quote from: rsjsouza on February 22, 2018, 12:35:45 pmIn the case of lights the fuse is only in the main fuse box. Usually a 15A fuse per circuit. In most normal sized houses there would be "upstairs" and "downstairs" light circuits. Outdoor lights would usually be separately wired and fused.

author: Ian.M
author_rank: Super Contributor
timestamp: February 22, 2018, 01:13:01 pm
content: UK Lighting circuits are usually *NOT* fused at the light fittings although some multi-bulb decorative fittings may be fused to protect wiring in the fitting of under 1mm2CSA and/or prevent overload by the substitution of higher wattage bulbs. They are 5A radial circuits, usually run with 1mm2flat twin + earth cable, protected by a fuse, breaker or RCBO at the consumer unit. You'll also see 1.5mm2cable for long runs.Higher current lighting circuits are also found in larger dwellings, but they need appropriately rated cables - you cant just pop a 15A breaker in on an old 1mm2circuit to upgrade it.In all cases, you'd isolate the circuit as described above.

author: Monkeh
author_rank: Super Contributor
timestamp: February 22, 2018, 01:38:38 pm
content: Quote from: Vic20 on February 20, 2018, 09:43:02 amI don't know how it's done in Spain, but we don't use bits of wet string as conductors. A little current passing through the CPC will not cause a bloody fire.

author: paulca
author_rank: Super Contributor
timestamp: February 22, 2018, 03:00:34 pm
content: Quote from: Ian.M on February 22, 2018, 01:13:01 pmOpps, yes, 5A, not 15A.I think sparks call them branch and spur, so the kinds of fan out in a tree with one main line/chain and spurs branching off it.