How NOT to work on mains - Page 1
Forum section: electronics / general

author: b_force
author_rank: Super Contributor
timestamp: October 20, 2017, 01:09:05 pm
content: There has always been a lot of discussion around safety and how strict certain rules & regulations need to be followed.Some people know I am pretty easy about it, as long as people use their brains.The following example is however something I wouldn't approve and I would like to show (and teach) people why.In this case it's more about showing it to the public on a very bad way and pretend it's perfectly normal way of working.Although I already get the shivers how (apparently) a standard Canadian fuse/distribution box/board and wiring looks like (would be illegal here), the main problem is that this guy doesn't seem to understand a few basics.Just a few things to point out;- You are working in a CAT III (and CAT II) environment. This means ALWAYS switch off the main switch/fuse (if possible) and are at LEAST very much aware of the risks (in the video the guy clearly isn't)- Stick to the correct colour code for wiring. Not only for yourself, but also for any 3rd party (electrician or whatever) who needs to do any repairs/when selling the house.Is it not just for plain safety, the insurance company won't pay a cent if they discover (and most times they will) you goofed up something with the electricity.Not something you want if your house burns down (not very likely, but still a possibility) or someone else gets injured.I know it depends on the country you're in, but I would never leave (relatively) high power mains cables just flapping in the breeze.One hit with a heavy (sharp) object, like some timbre board and you can already risk quite some damage on the cables.In fact it's mandatory to put them through a PVC pipe in many other countries.I like Matthias videos a lot, and I understand that some people get all annoyed about safety complains, but this is right on the other side of the spectrumIn this case it doesn't cost much more and isn't much more work, instead being lazy and frugal to take a lot of extra risk.Just unnecessary and far from being smart = not using brains.https://youtu.be/wsw7a4hvMBg

author: schmitt trigger
author_rank: Super Contributor
timestamp: October 20, 2017, 01:31:21 pm
content: I agree with you, it would take you an extra 60 seconds to take down the main breaker. And if you are really safety-conscious, put a lock and a tag.The problem with this video, is that we don't know how many hundreds of inexperienced people who watch this video, and follow those steps.

author: b_force
author_rank: Super Contributor
timestamp: October 20, 2017, 02:56:33 pm
content: Quote from: schmitt trigger on October 20, 2017, 01:31:21 pmEXACTLY my point!I mean all these heated debates on the forum are just being a bit pedantic about small details.I think most engineers and electronics hobbyists understand that it's something to be careful with (only how much is still a debate, but let's not go into that).Like you said, in this case there are people who have 'some idea' of electricity, and that's were the real trouble starts.Matthias is smart enough not to get into a lot of trouble with it (he is also very aware how he moves/works), but I don't think many people would understand the importance of it.

author: rrinker
author_rank: Super Contributor
timestamp: October 20, 2017, 03:03:06 pm
content: I won't take the cover off my box (US same as Canadian) without turning off the main breaker. Certainly not install or a remove a branch circuit breaker without killing the main. But then, I've seen professional electricians replace a switch or outlet and not turn off the branch circuit - sorry, I prefer to not take that chance and kill (and check - at least until I get to know just how my house is wired) before I touch anything mains - even if it is a wimpy 120V compared to all you 240V places.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: October 20, 2017, 03:29:23 pm
content: Quote from: b_force on October 20, 2017, 01:09:05 pmThe colour code is correct for Canada.The black is hot, the red is the other hot. The red sheath is used to indicate 220VThe 110V outlets with three wires plus bare ground is standard wiring in most Canadian Kitchens. This allows 15A to be taken from each hot wire, 30A total. Nothing wrong with colour code here.I echo the concerns about working on a live panel. I would turn the main breaker off if I was working on the panel.I don't think that the 220V outlets should be mounted so close to the floor. I belief that there is a minimum height above the floor. Outlets are normally 12 - 18 inches above the floor. (I am sure it varies from location to location).Regards,Jay_Diddy_B

author: IanB
author_rank: Super Contributor
timestamp: October 20, 2017, 03:45:19 pm
content: Quote from: b_force on October 20, 2017, 01:09:05 pmHe did.QuoteIt's against code to put Romex in a conduit in North America.I think you should avoid trying to translate local practices to a totally different jurisdiction. Every country has different codes and different traditions.

author: kripton2035
author_rank: Super Contributor
timestamp: October 20, 2017, 03:48:21 pm
content: like he said in the video, if he shuts the main breaker down, he wouldn't have any light to shoot the video ...

author: bd139
author_rank: Super Contributor
timestamp: October 20, 2017, 04:26:25 pm
content: Quote from: kripton2035 on October 20, 2017, 03:48:21 pmOk we've gone from linear idiocy to exponential idiocy now.Just use a flipping video light or GTFO the Internet.Then again I know someone who's an electrician who is much worse than this. He doesn't even have a working meter, drills holes in walls without checking for pipes and cables (unsuccessfully numerous times) and his shed went up in flames.

author: Lightages
author_rank: Unknown
timestamp: October 20, 2017, 05:15:46 pm
content: This is why I am so insistent that a meter actually match the rating it claims and I why I say that CATIII is needed for a general meter It is to protect people from themselves, and for the meter to survive another day.Safety ratings on meters are not for those who know what they are doing or want to be careful, but rather for fools and the uneducated.

author: macboy
author_rank: Super Contributor
timestamp: October 20, 2017, 05:28:29 pm
content: Quote from: IanB on October 20, 2017, 03:45:19 pmRomex is a brand name, generically it is NMD90 cable, and it is definitely allowed inside conduit.

author: b_force
author_rank: Super Contributor
timestamp: October 20, 2017, 05:50:23 pm
content: Quote from: Lightages on October 20, 2017, 05:15:46 pmA fool shouldn't even look at it, period.They should not even touch a multimeter and use it for these purposes.Quote from: macboy on October 20, 2017, 05:28:29 pmThanks for the clarification, I guess we just call it double isolated wire.I am not familiar with these cables at all, so forgive me, but in general the ones I am used to ar not as sturdy as PVC pipes for electricity.Besides running loose wires is just asking for trouble.It also makes wiring the cables trough the building a billions times easier.I don't see any technical or safety reasons why it would be bad to put any wire into some kind of plastic piping?Unless you're pushing to much current trough them and they are getting way to hot, but than you're doing it wrong anyway.I think it's obvious I am not judgemental, but just putting out the differences.Btw, if I recall well, Matthias was actually saying in the video that he used a slightly different colour coding?Here an example picture.Not a very good one, but it's about the idea.(weird that the box is made out of metal)

author: HighVoltage
author_rank: Super Contributor
timestamp: October 20, 2017, 08:19:34 pm
content: Even in Germany I have seen people working on 3 phase 400 V panels without turning them off.And then even use non insulated screw drivers

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: October 20, 2017, 09:08:53 pm
content: The guy is an f#ing idiot to be working on BUSBARS with the power on. If he slips he could get a nasty burn and a flash injury to his eyes.A slightly different matter from working on the output side of an installed breaker with the power on, where you at least have the breaker to limit the energy if there is a short.Plus if you're going to use a meter on busbars you want sheathed probes with only the tip exposed.Not sure about the USA, but in the UK if you use a black wire for live you should mark it such at both ends, for example by putting a ring of red tape around it. We don't use split phase supplies but the same situation arises with light switches where there is a switched live.

author: eugenenine
author_rank: Frequent Contributor
timestamp: October 20, 2017, 09:16:01 pm
content: Different color code in the US, black is hot here, cold is neutral red is second hot for 220 or switched hot for a three way switch. And inside of floors and walls no conduit so what he's doing is up to code. Other than the risk of touching the bus bar he's not doing anything else unsafe, and I've seen many electricians pop new breakers in without shutting off the main, if you are careful about it there is little risk. Careful being insulated mat and shoes, only one hand in the box at a time, etc.

author: G7PSK
author_rank: Super Contributor
timestamp: October 20, 2017, 09:24:51 pm
content: Quote from: HighVoltage on October 20, 2017, 08:19:34 pmI have seen men working on 415 3 phase power lines in a water filled hole in the road in pouring rain while the power is still on, working hot is safe as long as you know what you are doing and have the requisite safety equipment and precautions in place.

author: Nusa
author_rank: Super Contributor
timestamp: October 20, 2017, 09:26:57 pm
content: Quote from: macboy on October 20, 2017, 05:28:29 pmActually the answer is maybe, because it depends on where the conduit is. NMD = Non-Metallic Dry service rating, which means it cannot be installed in wet locations. The NEC decrees that the interior of raceways installed underground or in wet locations are to be considered wet locations. In other words, most of the locations where the code REQUIRES conduit are considered wet and NMD cannot be used. So the rule of thumb isn't that far from the total truth in the USA. And I suspect Canada isn't much different.But you're also right that it's allowable in the basement installation shown in the video. But what he did do looks adequate to me, except for the idiocy with the hot electrical panel. I wouldn't have put outlets in the accidental kick area either, but it's his house.

author: b_force
author_rank: Super Contributor
timestamp: October 20, 2017, 09:32:23 pm
content: Quote from: eugenenine on October 20, 2017, 09:16:01 pmThe 'no conduit' still really completely explodes my mind, because that's actually a very VERY smart addition to wiring.I don't care HOW correct and careful you are with wiring, but piping (conduit) already gives you so much more security and safety.Like accidentally hitting wires (and therefor short circuiting).In any logical way of thinking, it's an extremely good remedy to prevent anything bad plus it makes wiring so much easier.Like I said before, it's not that difficult to hit your wires with something big if they are all flapping in the breeze.Colour codes are all different.In most European countries it's brown for live, blue for neutral and 'yellow AND green' for earth.Wires coming from (light) switches) are black, and return in the same colour (so blue)

author: Monkeh
author_rank: Super Contributor
timestamp: October 20, 2017, 10:21:53 pm
content: Y'know, I really can't remember the last time I hit some wiresin a wallwith 'something big'...And.. no, shoving that type of wire in a conduit doesn't make things easier..

author: tautech
author_rank: Super Contributor
timestamp: October 20, 2017, 10:49:10 pm
content: Until you've spanned a few generations and worked with sparkies that have "been around" it's far too easy to denigrate what was perfectly acceptable practices in other jurisdictionsorfrom another earlier time.ExampleWhen power came to our part of the world in 1935 ALL installation was in steel conduit, the pitch and cotton covered conductors were drawn though from inspection cover to inspection cover that was mandatory at Tee junctions or 900bends.There were NO earth cables, instead the steel conduit was the earth.I still have circuits like this in my house that give zero problems after all this time.

author: nctnico
author_rank: Super Contributor
timestamp: October 20, 2017, 11:08:29 pm
content: Quote from: G7PSK on October 20, 2017, 09:24:51 pmLike an extra person to finish the job if the first one dies?

author: b_force
author_rank: Super Contributor
timestamp: October 20, 2017, 11:14:56 pm
content: Quote from: Monkeh on October 20, 2017, 10:21:53 pmI was talking about 'flapping in the breeze", so that's clearly NOT in the wall.Although, you can still drill into walls!It's not about how big the wire is, it's about isolation or simply getting stuck with wires.Quote from: tautech on October 20, 2017, 10:49:10 pmAaaah, the good old days, it was all copper conduct here.Like, really, looking for the worst solutions EVER!I can also remember my grandma asking that everything she touched tickled, lol, jeeze.

author: RGB255_0_0
author_rank: Frequent Contributor
timestamp: October 20, 2017, 11:16:32 pm
content: Have no problems with the cable not being in a conduit/raceway as long as it's tacked down, thus not flapping in the breeze.We all get worked up over different rules in different countries for little good reason, even though it's perfectly fine.I clenched my anus a few times with his gesturing at the live panel though!

author: Marco
author_rank: Super Contributor
timestamp: October 20, 2017, 11:52:52 pm
content: Quote from: b_force on October 20, 2017, 02:56:33 pmWhat does intelligence have to do with it? You're only driven by intelligence until the right distraction comes along.Fuck ups are a given in the long run, prevent them from happening as much as feasible, prevent them from having bad consequences as much as feasible ... and have a will.

author: b_force
author_rank: Super Contributor
timestamp: October 21, 2017, 12:09:15 am
content: Quote from: Marco on October 20, 2017, 11:52:52 pmIntelligence says (mostly) something about how someone can overlook a situation.So if you take a risk, you can overlook the consequences.

author: Marco
author_rank: Super Contributor
timestamp: October 21, 2017, 12:42:56 am
content: The consequences are the outcome of a stochastic system, intelligence can't turn the illusion of control into actual control.

author: Unknown
author_rank: Unknown
timestamp: October 21, 2017, 02:45:50 am
content: What possible purpose was there in placing his finger on a live busbar is beyond me. Matthias is a clever guy and his videos typically focus on his clever contraptions. I can't help but think he thought it would be "clever" to show him touching a live busbar without getting shocked.

author: IanB
author_rank: Super Contributor
timestamp: October 21, 2017, 02:50:03 am
content: Quote from: steverino on October 21, 2017, 02:45:50 amPerhaps it shows how knowledge can keep you safe? If you know exactly where and what form danger takes, you are better able to avoid it. If you do not know how to recognize danger you are likely to be scared of everything, and at some point you will stumble into danger without seeing it.

author: mcookieman
author_rank: Contributor
timestamp: October 21, 2017, 02:58:08 am
content: I'm not convinced behind his reasoning for sharing the neutrals in his additional 120v sockets as well.. If the power factors of the loads are different then it is possible to exceed the rating of the cabling.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: October 21, 2017, 03:36:06 am
content: Quote from: mcookieman on October 21, 2017, 02:58:08 amIt is common practices to share the neutral like he did.The worst case situation would be one load leading by 45 degrees (pf 0.707) and one load lagging by 45 degrees.Under these conditions the maximum current in the neutral would be 1.41 x maximum phase current. For 15A circuits this would be 21A in the neutral lead. Each load would 1.16kW with a 0.707 pf.These would be pretty special loads.Jay_Diddy_B

author: Gregg
author_rank: Super Contributor
timestamp: October 21, 2017, 03:50:51 am
content: Quote from: mcookieman on October 21, 2017, 02:58:08 amSharing the neutrals is OK by the US National Electric Code and it makes sense because the neutral is connected to the center tap of the supply transformer. Power used on one half of the 240 volt center neutral system is balanced out by power on the other half; same as a 240 volt load. In other words if one half has a 10 amp load and the other half has a 10 amp load, the neutral is carrying virtually no current.

author: b_force
author_rank: Super Contributor
timestamp: October 21, 2017, 08:43:49 am
content: Quote from: mcookieman on October 21, 2017, 02:58:08 amThe proper way of doing this is therefore taking cables that are rated (much) higher than the fuse. Which makes a lot of sense and is even mandatory in most countries. The fuse should always and only be the limit, not anything else.If you doing it well you also just standarize the fuses and wiring to a set value. (10, 16, 20 and 26A for example)But I have seen many "safety codes" in some countries that are just simply dangerous.For example, some countries don't work with a real earth/ground fuse/switch, but they only detect the imbalance of live and neutral. That is just asking for trouble. Not only is it possible to have accidentaly both shorted to ground (which means there is still nothing out of balans), it also doesn't care if there are any issies with the secundary side. Which can lead to very dangerous situations.(I have even showed people these situations)

author: jthomas
author_rank: Newbie
timestamp: October 21, 2017, 09:30:09 am
content: Quote from: IanMacdonald on October 20, 2017, 09:08:53 pmWhen I was in the trade for a short while, we used brown heatshrink sleeving, so at the point of termination it looked very obviously like a live wire (and it can't fall off, like tape). I've encountered quite a few suspicious-looking "is that meant to be live or not?" wires which required careful probing... and one of our goals when leaving a site was to make the next guy's job easier than ours was! If it looks like shit, it probably is.

author: tautech
author_rank: Super Contributor
timestamp: October 21, 2017, 09:49:24 am
content: Quote from: b_force on October 20, 2017, 11:14:56 pmAnd you well know that the circuits in that case should have been checked for the integrity of the earth bonding.Anyone that didn't rightly gets LOL treatment in return.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: October 21, 2017, 02:15:56 pm
content: Quote from: jthomas on October 21, 2017, 09:30:09 amBrown is the correct colour for hot in Europe.Blue is the correct colour for neutral in Europe.in USA and CanadaBlack is the correct color for HotRed is used for a 2nd hot, split phase circuits and two-way switchesWhite is the correct color for neutral.In three-phase circuits the phases are black wires marked with red, yellow and blue tapes.Regards,Jay_Diddy_B

author: Jeroen3
author_rank: Super Contributor
timestamp: October 21, 2017, 02:31:04 pm
content: Will this topic be going intoabout who's got the best wiring colors? Or why CAT ratings are super important becauseother peopleput their life in danger?

author: Monkeh
author_rank: Super Contributor
timestamp: October 21, 2017, 02:31:23 pm
content: Quote from: b_force on October 21, 2017, 08:43:49 amWhat on earth are you on about? RCDs? They all work by detecting current imbalance. Yes, shorting either side (.. well, neutral, line is going to have a whole different problem) to earth on the secondary side will cause an imbalance and lead to a trip. On the primary side, neutral and earth are already connected..

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 21, 2017, 07:35:48 pm
content: This thread is a better illustration of the lack of cultural relativism than of electrical wiring.Tim