Beware of main cable wire colors  - Page 1
Forum section: electronics / beginners

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: January 03, 2018, 04:07:58 pm
content: Dear All,I used to think that for all main cables that were Blue/Brown/Yellow-Green,The phase was the Brown and the neutral the Blue.But to my surprise, as I checked a standard ( Male CEE 7/6 plug , Female C13) computer cable,of which I had cut the C13 side, I saw that it was wired in the reverse way,with the Brown cable at the neutral pin, and the Blue cable at the phase pin.Unfortunately, I have no Idea where precisely this cable comes from, but I know it as been used fora screen in a lab, as the label was still there. No marks on the cable, but all labels that you can imagine on themale (10/16A 250V) plug.I will be more cautious now ! I have indeed used this cable many times for testing purposes, assuming the brown was the phase. Hopefully, this was not critical.

author: Monkeh
author_rank: Super Contributor
timestamp: January 03, 2018, 04:11:35 pm
content: CEE 7/5 sockets don't have any universally accepted polarity, so uhm..

author: grumpydoc
author_rank: Super Contributor
timestamp: January 03, 2018, 04:41:40 pm
content: In France it is customary to wire phase on the right looking at the socket (with earth pin on top).However I think most of the CEE/IEC leads are wired to the German pattern which is the other way around hence then need to be careful as youwillend up with the blue wire carrying phase.Mind you don't get me started on French wiring colours - the actual rule is green/yellow=earth, blue=neutral and *anything*else* is OK for live (black and red are common for "regular" phase connections and they quite like purple and orange for "control" circuits). Ithink3-phase installations, at least, are supposed to be brown/grey/back but I'm not 100% sure.Even with so many colours to choose from Istillfound blue and even green/yellow carrying phase when I dealt with the worse of the wiring anomalies in my place in France.This is one of the junction boxes that I still need to sort - i mean, what the heck are the two bits of thin signal wire doing attached to 240V live.

author: Monkeh
author_rank: Super Contributor
timestamp: January 03, 2018, 04:44:32 pm
content: German (CEE 7/3 and 7/4) connectors are unpolarised anyway!

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: January 03, 2018, 04:54:21 pm
content: Quote from: grumpydoc on January 03, 2018, 04:41:40 pmSo from what you say, it is normal to find both polarity in the CEE 7/6 plugs.My concern is that I have taken care that in my workshop, all plugs are the same way, and I thus need now to take care of whichcable I use for experiments, in order to be sure that the Live if the brown and the Neutral the Blue.As I said, now that I know, I will be more cautious.

author: grumpydoc
author_rank: Super Contributor
timestamp: January 03, 2018, 04:55:23 pm
content: Quote from: Monkeh on January 03, 2018, 04:44:32 pmYes but all the 7/7 plugs I have encountered make blue live when inserted in France.

author: Monkeh
author_rank: Super Contributor
timestamp: January 03, 2018, 04:55:51 pm
content: Quote from: JacquesBBB on January 03, 2018, 04:54:21 pmOr just treat them both equally as you should. In the majority of cases it doesn't matter which is which - if it does, consider why and how to stop it mattering.

author: Damianos
author_rank: Frequent Contributor
timestamp: January 04, 2018, 07:33:49 am
content: Quote from: Monkeh on January 03, 2018, 04:55:51 pmAny power line wire that is not permanently connected (on a fixed installation) must be considered as "hot"...

author: paulca
author_rank: Super Contributor
timestamp: January 04, 2018, 08:41:51 am
content: Last mains lead I hacked apart (a computer IEC lead) to use gave me Blue, Black, Black with a yellow stripe. I kinda guessed. Blue-N, Black-L, Black/Yellow-E. But I did test conductivity with the relevant pins on the plug. I was also very surprised to see excessively thin conductors inside the cables. The fuse was a 3A but these conductors look like they were made to a price that will barely carry three amps. My load would max 2A and only rarely. Poor the fool who swaps in a 13A fuse and tries to use one of these mains leads to run a kettle!In the UK mains plug wire colours died about 10+ years ago when it was decided that all electrical goods must come with a moulded, untamperable, fitted, fused plug. Consumers are no longer expected to wire plugs, ever. You need a hi-viz vest, the correct gloves and the correct hat, plus a H&S course to be able to open a plug. So it no longer matters what colour of wires factories use to make mains leads, anything goes. If you happen to spike yourself on a single piece of multi-strand wire, be sure and log it in the accident book!If you needed to know, how do you differentiate between N and L with a multi-meter? If you don't have the plug to reference pins. Test voltage referenced to ground? The N should be close, the L not so? (I'm in the UK).

author: grumpydoc
author_rank: Super Contributor
timestamp: January 04, 2018, 11:36:28 am
content: Quote from: paulca on January 04, 2018, 08:41:51 amHigh temp IEC plugs/sockets for kettles have an extra ridge in the socket and notch in the plug so they are incompatible with bog standard IEC plugs - hopefully this means cheap IEC leads such as your description shouldn't fit (not that I put anything past the manufacturers of the really cheap crappy leads).

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: January 04, 2018, 12:42:00 pm
content: I found this page on the web with a nice summaryhttp://www.corporatocracypk.com/2017/10/power-cords-plugs-connectors-and-their-difference.htmlDo all agree that on the C13 side, the polarity should be always the same, with brown as Live and Blue as neutral ?So as if one put a fuse in a device, he can be sure to put it on the live cable.

author: Monkeh
author_rank: Super Contributor
timestamp: January 04, 2018, 12:44:24 pm
content: Quote from: JacquesBBB on January 04, 2018, 12:42:00 pmIt doesn't matter, you have no assured polarity on the other end.Both line and neutral conductors are live - they are equivalent.

author: jeroen79
author_rank: Frequent Contributor
timestamp: January 04, 2018, 06:08:58 pm
content: Quote from: Monkeh on January 04, 2018, 12:44:24 pmRight.When a device is in use it should not have any external live parts that the user could touch.If it is to be opened for maintenace (or tinkering) then this should be done by someone who is aware of the risks involved.

author: dmills
author_rank: Super Contributor
timestamp: January 04, 2018, 06:09:22 pm
content: Quote from: MonkehThis is the only correct way to roll at least as far as insulation in concerned, both phase (Line) and neutral are live (current carrying in normal conditions) conductors.Since appliance in built fusing is largely about fire safety (The upstream supply protection should be organised to disconnect fast enough to provide touch protection in a class I appliance), it actually makes little difference which leg it is in, apart from when working inside the chassis where convention expects it to be in the live (But you will not catch me touching a 'neutral' even if I know the fuse was blown).Regards, Dan.

author: Rick Law
author_rank: Super Contributor
timestamp: January 04, 2018, 06:39:42 pm
content: Add in the so called "warm white" light bulbs which change the color you see.I for one vote for a "digital representation". Three lines (around the jacket) of black on white, green or grey; with these bands repeated the entire length of the wire:Wide Wide Wide = hotWide Wide thin = neutralWide thin thin = groundA blank space to separate groups of bands is not necessary, but for a nice touch, print the H N or G as separator.This arrangement would be visible under poor lighting (as inside an appliance may be)But of course that would make the wires a bit more costly...

author: paulca
author_rank: Super Contributor
timestamp: January 04, 2018, 06:50:58 pm
content: I smell a case of "Forget the truth, the truth can hurt you. Accept these lies and you will be safe."I have held a neutral wire in my hand at a plug, back when I was younger and arguably more stupid. I have also held a live in my hand, which happily lit up a main tester as I was sure I would not get a shock as long as I didn't complete a circuit. I didn't.It hasn't always gone so well though. I tried the same thing on a circuit under load and got a shock, literally and metaphorically. It seems that touching the element of an 1.5Kw electric fire before it get too hot to induces a mild shock. Not the same kind of shock you get when the back of the plug comes off in your hand and you grab the Earth and Live in one hand, but still a shock.Don't try this at home kids.Part of me still thinks it should fused on the live. If you fuse the neutral and the fuse blows there is still +/-110V floating around inside the device and all it needs is a ground to ruin your day. If it finds a ground, such as case to earth you are then relying entirely on your meter box fuse/breaker to kill the current. I'd feel much more comfortable with a neutral still connected and the live terminated at the plug. And I know that most 2 pin mains plugs are non-polar, though most do not have metal cases. Metal cased devices seem to have polarised, live fused and earthed plugs in the UK. And yes I know that not all countries use the same standards, but:Who you gonna trust?