Testing polarity on mains electrical installations, to ensure line and neutral are connected correctly. Website: xo4.uk/?DR0 Patreon: / jwflame Contact info, sending stuff in etc.: xo4.uk/?YTT
...You’re a great education and valuable safety first port of call watch... PSA EXPERT . Although a little monotone or just matter of fact in delivery. I’m still not sure,but I am still learning so fill your boots. Keep doing what your doing. All the families and handymen your protecting is a testament to you. Safe knowledge safety net. 🙏
thanks! never knew that you could test this way. not being fond of AC what little I have done it with a dead line and by color alone. thanks for your videos WELL DONE.
Another reason for polarisation is so that internal fuses in equipment are on the line/live side. That way when the fuse blows, the internals of the device aren't still live when a fault has occurred.
Always worth checking the output of the meter. Don't assume just because the Provider (and/or their contractor) did the installation it will be correct. I've had it where it was reversed; on one memorable occasion at an aquarium shop!
And in one of our local aquarium shops the owner has some of the aerators for the tanks bearing those Chinese 13Amp plugtpos which have no fuse, and flexible cord that looks dubious into the bargain. An electrifying experience awaits. Frying tonight?
In the states we have a tester that plugs into the outlet & has LEDs to show you what the status of the polarity is.Like a go/no go gauge.(shows hot reversed neutral reversed etc.)
My interest in electrics stems from the fact I got a severe electric shock from an Edison screw bulb. I now know what it feels like to be an Elephant in America. The idiots who installed the electrics in my business in Cambodia reversed the polarity of the entire system and I got electrocuted while kneeling on the bar to change one of the bulbs. I must have gripped the screw thread, which was live, because I crushed the Compact Fluorescent in my hand while screaming like a piggy from the deep south. The funny thing about it now I look back is I actually turned the light switch off thinking that the electricity to the light was isolated. I know better now. Anyway, if you ever want to see what a country looks like without any electrical regulations, then visit Cambodia. It's a shocking experience, literally.
Never assume that the polarity is respected. In my country before the new EU wiring color usage in a lot of installation they used the same color for L and N, the only real standard was green/yellow for ground, everything else whatever. Also a lot of people that installs lightbulb holder really don't care about polarity, and wire them randomly. Also never assume that turning off a switch it will interrupt L and not N, also there is an old way to do 2-way switching that produced the effect that the lightbulb can be off because the two terminals are at full live voltage.
I bought one of them plugs that you plug into the wall that will light up with 3 colours to indicate correct wiring. It's the *Kewtech KEWCHECK103 Mains Wiring Socket Tester.* I was think of using it on the lighting circuit with the aid of a 3 pin socket fitted to the ceiling rose wiring to test it with that. Is that something you could recommend? Seems easy just to isolate the power and wago connect the plug into the circuit, turn on the power and test with that device.
@@jwflame OK, thanks John. If the basics don't come back OK, I shall call an electrician. Trouble is I spent a day and a half troubleshooting and fixing the issue an electrician had left after getting paid 600 for the whole job. One 2 way switch was not turning on at all times. I've fixed the issue and used my multimeter for continuity to earth in CU. But wanted to do additional testing.
Im doing Electrical Installation Lvl 2 at college and I still find Polarity extremely confusing but thanks for the help anyways.. These Videos are good :)
Polarity on AC is just about ensuring L & N are in the correct place, and things like light switches are connected to L only. It's not negative/positive.
Is it really the case that the outer threaded part of a light fitting is accessible when there's a lamp installed? Surely it's not acceptable to have even the neutral exposed in normal use on any electrical equipment. Of course, lamp fittings are an exception to the normal requirement that no live components can be exposed without the use of tools, but even a neutral which can be touched with a lamp fitted seems odd (the exposure of live contacts with no lamp installed is, presumably, just historical - other designs, like the GU10 base, are safer).
Nice vid but why do you have to fuse all the wall plugs? We (Australia) just fuse/rcd the circuit from the board. Also over here in the power board you would have a neutral link like the esrth one you showed and an earth link with a jumper from neutral to earth, why do you folks not have that?
Plugs have fuses as the outlets are typically connected to 32A circuits, without fuses in the plug very large wire would be needed for appliances. On those installations which have the earth and neutral connected it is done in the supplier's equipment before the meter, and not within the installation.
Thanks for that .... now fogs me though why your meter is setup like that. We have the drop in via service fuse DIRECT to the meter. Up to and including this point is supplier equipment and not to be meddled with without special clearance/courses. Then from there it goes via the main fuse/rcd and into the subs (lights, power1, power2, stove, hotwater etc) of which power is usually 16a each, lights 8a and stove/hw each 20-30a. However all this is on the same board side by side. Thus the bridges are all on the same board including that earth strapping. Given the cost of copper I much prefer our system :P since the copper to handle a 32a line would be phenomenal in cost (I know my 4-12g 12vDC copper is shocking with 2-4g averaging up to $10pm). Also with our system when you blow one side of the house it doesn't take out the entire house. On that note I notice we have bigger houses too. Was watching a property searching show from the BBC the other day and they were going on about how the second bedroom in a new block of flats was big .... it was smaller than my laundry was in my last flat lol and smaller again I think than my bathroom in that flat and only 1/2-2/3 the size of my second bedroom in that flat. My lounge/kitchen was 3 times bigger and they were saying how big it was. Had me stumped. We are now in a 4br house and our main br is the same size of that second b/r, I consider our bedroom small because of the space left after the inbuilts and it is still 2-3 times bigger. So property size may influence the wiring a bit?
I don't know why you think the house supply fuse (63A old 100A new UK) would blow and take out the entire house at any time. The RCDs (which protect power and lighting circuits etc.) in the Consumer Unit would trip well before the supply fuses. Maybe I misread or misunderstood something?
Jamal Tyrone not sure what your reply is referring to as noone I can see suggested anything about the main fuse/RCD and especially not at them ratings either. I believe our service fuses are ~60amp but I'm not pulling our fuse to check (most pre naughties houses here are still fuses).
I was referring to the line "Also with our system when you blow one side of the house it doesn't take out the entire house." I don't understand how this isn't true of our system since earth faults trip RCDs (or burn the fuse wire) which only results in one circuit ever going out of service until it's repaired. In the UK supply fuses are either 63 amp in most old houses (like our bungalow) but new builds apparently have 100 amp according to what I've been taught so far. Which is odd seeing as most homes now use lower power lighting and lower power white goods. Maybe it's been uprated to allow for high power showers on the main consumer unit rather than a separate one like we have? Oh, and to get around the copper price issue we technically use underrated cable on our 32 amp rings. 2.5mm cable which according to our On-Site Guide is only good for up to 27 amps. It must be passed my bedtime I'm typing some crazy shit. :D
Out of interest, how would you pick up one socket or light in the middle of a circuit connected incorrectly? If the Lives were connected together but in the neutral terminal and vice versa you would still have continuity, would you just pick up the incorrect polarity on the live test? Many thanks for the great videos by the way!
What is the need for polarity testing in electrical installation considering the line wire is red and neutral wire is black, which can be verified visually?
Wire colours are only valid for identification if they have been correctly connected. If someone had connected red as neutral and black as line at one part of a circuit, the rest of it would be wrong even if the colours were correctly connected.
How do US power cables work as they can be inserted either way so how is Line / neutral connected? I assume on a UK plug the line is switching + and - hence the AC part, but the neutral is always the neutral. so I don't understand why half the time US appliances don't work as line and neutral are the wrong way around. thanks
We also have this in Germany. The plug is symmetrical and can be plugged in both ways. Earth is always earth but Neutral and Line can be switched (the connection to the device). The polarity is changing 50 times a second (50 Hz) here. Neutral is connected with Earth. This is the reason why you don't get shocked when you touch it. (Warning. I'm not sure if I'm talking bs.)
A good amount of power strips are unsafe here because of this. When you flick the switch some of them only disconnect one wire. So it's a 50:50 chance of getting the line one.
No internal circuitry is required. As John stated, there is no polarity on AC - Line and Neutral are just two anti-phase (180° out of phase) sinewaves.
A switch with only 1 set of contacts, used to switch line only. A double pole switch has 2 separate sets of contacts and switches both line and neutral at the same time.
Mawerick77 But when common electrical appliance running on AC is used, it does not cause damage if polarity is wrong. This also means that Live and neutral are equally deadly.
Neutral is generally / should be tied to ground / earth but Line/Live is obviously not. Therefore corectly a wired circuit cannot give you a shock between Neutral & Earth. However, without protection in the circuit, Line/Live will give you a shock between Neutral or Ground. AC appliances generally don't care if they get L/N or N/L for there supply.
The switch is on the line wire. If you have them reversed, the appliance could still be live right through the appliance and back to the switch even if switched off.
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