Testing Lightswitches with Multimeter

1984ReturnsForReal_2

vaio wrote: »

It's tricky, GS38 says multimeters are non preferred, not not approved

Fluke say my meter is IEC 1010 cat 4 and so safe to use at the transformer end of the LV network

In practice my fluke gets used most days, the martindale lives in the test instrument case and gets used once a year when the NICEIC man comes calling

Lol

I know what you mean. But everyone is taught multimeters are not approved recently.

I have a Fluke 1653B, A Fluke Voltage Pen, A Fluke T5-1000 & it still scares me to death.

Not a lot of experience for me though. Maybe I will terrify myself less in the future.

vaio

Ahh, I on the other hand have way too much experience, first wiring regs I did was the 14th back in the '70s.

In those days digital meters didn't exist, multi meters were fragile analogue AVO (Mk 8?) and voltage testers were neon or drummond with a bulb. 35 years later both are still available, maybe it's the rule makers haven't kept up with the technology (or have shares in martindale!)

Bogtrotter

Maybe a multimeter is not approved to test is that in certain circumstances (like the light switch the OP is trying to test) you cannot always be sure of having a definite L-N-E to use your multimeter to test between all three.

Also basic multimeters usual only indicate voltage between the probes... thats not what you really want to know for safety the thing I would be most interested in is the voltage between the probes and me .

I think best to play safe and get a spark in to sort it for you... and I'd further suggest to get a different spark than the one who recommended you use a multimeter to test the circuit in the first place.

vaio

Bogtrotter wrote: »

.......Also basic multimeters usual only indicate voltage between the probes... thats not what you really want to know for safety the thing I would be most interested in is the voltage between the probes and me ..........

Just for the avoidance of doubt……

Using a multi meter or any two probe voltage indicating device to measure the voltage between an electric cable and a human is a very bad idea indeed.

At best it will make you jump, at worse it will kill you.

daggy

garethgas wrote: »

At least you seem to have an idea of what's required (ie a simple volt stick).
Unfortunately, your advice is wrong.
The OP must turn off multimeter, stand in a bucket of water, poke fingers into light holder.
If he doesn't scream like a big girlie, its not live.
If he does, that's natural selection for you.
Seriously, OP, are you for real? Are you really that stupid?
I'm all for being curteous but then again, I think your insulting my (and I guess others too) intelligence so I see no need for it in your case.
Now run along and get a grown up to do it for you.

WOW how very intelligent of you; I must say, watching you wax lyrical was as much fun as having a ham shank with a sandpaper glove on.

Who is curteous? Sounds like a gladiator. Does he know that Maximus?

I think you meant courteous.

Lets clarify a few things:

I'm far from stupid; but, I don't deny that I'm naive as far as electrcitity goes... to that end, I understand that I must isolate the circuit and indeed I even found the breakers that correspond to the u/lights and d/lights - :T yay me

I'd previously used a screwdriver tester, but the sparky said that they are not safe to use, so I bought a cheap multimeter and I wanted some advice on how to check the circuit was dead.

As several posters (who are clearly more semantically perceptive than you - or just not d**kheads) alluded to, I just wanted to be extra cautious. Get this, I even added a supplementary earth (instead of relying on the fixed lug alone) to the metal faceplates... har de har de har... I'm such a stupid noob, mock me mock me... :money:

or actually, is it, perhaps, that I'm being a little bit too anal about safety because I'm not a qualified sparky, so I don't know what is normal practice so far as safety goes and I don't want to f***ing electrocute my self or my family, so, get this... I asked on a forum in the hope that some professionals would reply.. and they did, but unfortunately it appears that 'Woody' also frequents this board.

I know that if the lightbulb doesn't turn on after I've tripped the breaker, it's highly probable that the circuit is safe, but I want to use something to double check.... what exactly is wrong with this?

This is a moneysaving forum and I am trying to save money by installing lightswitches myself; I respect the opinions of people who say I should get a sparky if I'm unsure, as they are trying to help.. and hey, it will be cheaper to pay to get them done then to pay for a funeral.

However, what I don't need is an idiot like you trying to big his ego up at the expensive of someonme else.

The irony of your post is that you are talking about natural selection - guess it doesn't always work; your daddy should have wore a condom!!!!

Next time you decide to spread your feathers and post such a pseudo pedantic display of your intellect, or lack thereof, please do everyone a favour and !!!!!!!!! Your post was neither helpful nor funny and merely served as a peacockesque display of the fact that you quite possible do not have two brain cells to rub together.

daggy

Leif wrote: »

The OP said "I just want to use the multimeter to test that the switch is dead" which suggests that he has indeed turned off the power at the switch box. Otherwise it is nice to see that you have posted a polite message unlike some here.

I'm not sure I like the discourteous and mocking tone of many other posts in this thread, there is no need for such rudeness. It is quite easy to warn someone that something is potentially lethal without being patronising or rude. And I think the OP realises that there is danger which is why he is asking for advice. Then again the faceless nature of the internet does sometimes encourage group unpleasantness.

My concern would be that a cheap probably made in China multimeter might be unreliable, and give inaccurate readings even after it has been tested and found to work in that one instance.

Another worry might be that someone else in the house might find sockets don't work, then flip the circuit breaker without the OP knowing until it is too late. :A (I have no idea what the angel symbol means but perhaps it is appropriate here.)

Thanks, I was beginning to think I couldn't convey my requirements and abilities in a relatively concise manor...

I agree, group cohesion seems to be rapid on the internet, especially if it's to e-stone someone.

I see your point RE the multimeter, I may take it back for a refund... it appears I have no need to use it.

ormus wrote: »

my main use for a multimeter is to use it as a continuity tester, not as a 240v voltmeter.
switch off the mains at the consumer unit and then use the meter to test for for continuity on (dead/not live) problem wiring/circuits.
i very rarely use mine to test "live" 240v circuits.
and i use extreme care.

That's essentially all I wanted to know - can I used it to effectively test that the circuit is dead, if not then I wont. I watched a few videos and read a few articles and it became apparent that multimeter are for testing continuity and how much power there is, not really for confirming there is no power.

cheers

vaio wrote: »

OP:

The approved method is....

Check meter is working on a known to be live circuit or proving device
Switch off circuit to be isolated and check L-N, L-E & N-E
Check meter is working on a known to be live circuit or proving device

Also worth noting that multi meters & un-fused test leads are not generally approved for this sort of testing. I don't think there are any approved non contact devices so volt sticks are out too

In the real practical world, I use my meter for checking voltages every day but it is a £200 fluke that gets used every day. If it was a £5 made in china job that got used twice a year I'd be less inclined to trust it

also, multi meters are high impedance so tend to show any induced voltages which can be confusing. Proper voltage testing devices are lower impedance so don't suffer from this problem.

Hi, I thought that was where I had to put the leads.. am I correct in thinking that neutral (switched live) to earth would bring up different readings depending on where the switch is?

thanks.

NOTE: the sparky never actually told me to get a multimeter, he simply said that he was told not to use the screwdriver testers in college. I then (wrongly) assumed I'd have to use a multimeter instead.... I now know the that the voltsticks are more suitable. Don't want to give a bad impression of someone.

Thanks for all of the replies... I fitted most of the lightswitches, just two left... thus far, obviously, I'm still alive.

Bogtrotter

daggy wrote: »

Hi, I thought that was where I had to put the leads.. am I correct in thinking that neutral (switched live) to earth would bring up different readings depending on where the switch is?

If you were to measure the voltage between the earth and the switched live in a correctly wired faultfree circuit the reading would change depending on the position of the switch. To make any inferences regarding the state of the supply requires you to ASSUME the circuit is correctly wired and faultfree. Not an assumption I'd like to make.

Leif

I am in a similar position to the OP, in that I have a socket that is protruding from the wall. Clearly the metal box behind the cover is not set far enough into the wall, and someone has made a bodge job of building up the plaster around the socket. I have removed the plaster bodge and touched up properly, and in principle it is not hard to fix the socket with a cold chisel or bolster and a hammer. The builder who is doing work for me says it is an easy DIY job, so I think quite a few professionals do not discourage amateurs from working on sockets. But I have not yet done anything because although I know to turn off the circuit at the mains and test that the socket is dead with a radio or some such, I am apprehensive, and wish to be sure I know what I am doing. I bought a cheap multimeter at a local shop, but the quality is poor, and I would not want to trust my life on a possibly badly made POS. So thank you to those people who have made constructive comments, even if that was to politely warn the amateur away from DIY work on sockets.

And a question. Is it sufficient to simply plug in a radio, check the socket works, then turn off the circuit at the fusebox (or remove the fuse), and check that the radio is off i.e. the socket is on the disabled circuit? I have heard about people using rubber mats etc, but I have no idea if these are needed.

daggy

Bogtrotter wrote: »

If you were to measure the voltage between the earth and the switched live in a correctly wired faultfree circuit the reading would change depending on the position of the switch. To make any inferences regarding the state of the supply requires you to ASSUME the circuit is correctly wired and faultfree. Not an assumption I'd like to make.

Thank you, that's what I thought with regards to the switch changing the voltage as if it's shut, there will be no power going to switched live and if open it will...

That's a very fair point with regards to how correct the wiring is, from what I've seen (and I'm obviously an amateur ) it looks like all of the wiring in the switch boxes has been done correctly, but I have no idea about the other stuff behind the walls etc.... and I'd certainly not be confident enough to try and find out. For now I'll stick to killing the power at the CU and operating the switch to see if anything lights up or turns on.

Cheers

ps. RE: voltsticks.... am I correct in thinking that they shouldn't be used as an indicator of a safe circuit?

After a bit of research it would seem it's common to use them to trace cables and to indicate the presence of power, but they shouldn't be used to indicate that there is no power?

I believe people say this as they don't want someone to use a voltstick as a standalone device, as it's important to fully isolate the circuit first and then confirm with the voltstick

Would the correct procedure be:

Check circuit with voltstick when it's definitely live (voltstick should indicate power)

Isolate circuit

Check with voltstick and there should be no indication of power

Also operate switch to verify no power

Is that a reasonably safe procedure?

thanks again

Leif wrote: »

I am in a similar position to the OP, in that I have a socket that is protruding from the wall. Clearly the metal box behind the cover is not set far enough into the wall, and someone has made a bodge job of building up the plaster around the socket. I have removed the plaster bodge and touched up properly, and in principle it is not hard to fix the socket with a cold chisel or bolster and a hammer. The builder who is doing work for me says it is an easy DIY job, so I think quite a few professionals do not discourage amateurs from working on sockets. But I have not yet done anything because although I know to turn off the circuit at the mains and test that the socket is dead with a radio or some such, I am apprehensive, and wish to be sure I know what I am doing. I bought a cheap multimeter at a local shop, but the quality is poor, and I would not want to trust my life on a possibly badly made POS. So thank you to those people who have made constructive comments, even if that was to politely warn the amateur away from DIY work on sockets.

And a question. Is it sufficient to simply plug in a radio, check the socket works, then turn off the circuit at the fusebox (or remove the fuse), and check that the radio is off i.e. the socket is on the disabled circuit? I have heard about people using rubber mats etc, but I have no idea if these are needed.

Thank you

The rubber mat is used to prevent you from becoming the earth wire? that's interesting I'd like to know if that works.

Your question could help me too, as I have a few sockets to wire in next and I was wondering if that was the best way to 'make safe' a socket.

Also, I currently have 1.5mm2 earth wire and cable and I need 2.5mm2 for use in sockets.

it's over £5 from b and q for 5 metres, indeed, the 1.5mm2 I bought was over £5 too. I then looked online and noticed you can buy 100m for less than £15... b and q is too expensive.

The stuff from b and q is the twisted type too, I'm not a fan as it is annoying and difficult to use; it's easier to get the unstranded type into the slots.

Anyway, I digress... my question is:

Could I buy some twin and earth 2.5mm2 cable from wilkinsons or a local store and just strip the earth wire out.. then use that with some green and yellow sleeving?

Will the earth cable be 2.5mm2 if the t+e is advertised as 2.5mm2?
Do I need to buy 2.5mm2 sleeving or is it one size fits all?
Apologies if that is a stupid question, but 'shy bairns get nowt'

daggy

andrew-b wrote: »

2.5mm2 t+e has live and neutral that are 2.5mm2..the earth is smaller at 1.5mm2 (See http://wiki.diyfaq.org.uk/index.php?title=Cables#Cable_Sizes ..lots of good DIY electrical advice buried on that website)

Yesterday i replaced a switch..i used my multimeter to double check nothing was live (as well as checking the bulb was out). Also used it to check continuity of earth. Sure my multimeter was about £20 but it's a hell of alot safer than prodding about with a testing screwdriver where you attempt to complete a circuit with your finger!

I then replaced half a dozen sockets. I used my multimeter again in a similar way. I also have this socket tester: http://www.screwfix.com/p/ced-plug-in-socket-tester/76975
...very basic one but it's nice to have some sort of confirmation you've correctly connected a socket and that the wires haven't popped out when you screw the faceplate back on as well as pick on a small number of common faults. Bit like your socket leif, it just so happens that one of those sockets i had to remove the backing box and sink it further in the wall as it was proud of the surface.

Thanks, so I'd actually need to buy 4mm t and e to get the correct earth cable for sockets? Is the sleeving one size fits all or?

I think I know, but how do you check these with your multimeter?

Test whilst power is on with probes to l+n, l+e, n+e?

Then same when off and shouldn't get a response?

In V~ mode?

Cheers