Edison screw lamp - i received electric shock!!

[Column79]

I went to change the bulb on my mums reading lamp and when I tried to remove the bulb (Edison Screw) I received an electric shock even though the s/w was in the off position. I have a LV3 cert in electrical technical but I lack experience as I own mine own landscape business so it has been a while since I did something electrical.

If my memory serves me well (i did get distinctions! ) It is probably a polarity issue. The metal screw itself forms the contacts for the circuit. If it isn't wired correctly or if the plug outlet is non-polarized the metal screw can become energised which can, well it does, present a shock hazard to anyone changing the bulb. The NEUTRAL should be connected to the thread and the LIVE to the center pin or terminal. But the thing that is confusing me is it is just a reading lamp bought from a shop so i think the problem must be coming from socket outlet itself.

I guess these are the couple of questions I need to get an answer too:

1)I'm going to isolate the circuit before i visually inspect it but what might I find? Do i expect to see the LIVE and NEUTRAL in the socket outlet to be terminated in the wrong terminals? If so, I guess it is just a quick case of rearrange them?

2)If the LIVE and NEUTRAL are in the correct terminals I guess i would have to inspect the plug of the lamp itself. Which surely can't be the case as it is pretty much new, as far as I know?

3)Should i carry out a polarity test of the ring and thus go through continuity and insulation resistance as well if:

a) It is neither of the above two questions and the LIVE and NEUTRAL have been terminated correctly

b)Or, if it is the LIVE and NEUTRAL conductors, and they have been terminated incorrectly,, and a I rearrange them, is it advisable to still carry out a continuity test, insulation resistance test and a polarity as well just to be on the safe side?

I ask because i just feel a bit under confident about going ahead with it as i don't want to burn the house down! I have knowledge but just haven't applied it in a while.

If you can help I'd really appreciate it.

Thanks,

Regards Column79

 

[Plonker 3]

So many questions. I would recomend getting a competant electrician too look at the fault. As without the correct equipment you could cause more problems rather than resolving them.

 

[FAA Greenie]

Hi Col.

I am assuming that the lamp has a plug on it? It will almost certainly be a polarity issue, either within the lamp unit itself or, unfortunately the socket outlet.

If so, what is basically happening is that the switching is in the neutral and you have touched the metal screw as you have unscrewed the lamp, which would have been permanently live.

If it's a recent purchase, take it back.

If you are going to have a look yourself, unplug it first. If there is anything you are unsure about, don't plug it back in. You are right, the live should be connected to the central contact.

if after this you suspect it is the socket itself, have someone come and have a look at it, it won't take long and shouldnt cost much. Especially if , as you say, you are not so confident in finding the fault.

Hope this helps

 

[markc123]

Sounds like whoever's done it has got the live on the outter contact, thus energising the base of the lamp...and because the bulb has blown, you think uve got the switch turned off and you actually haven't.

live should be to the center contact, and neutral to the outter contact.

As dillb says, ure probs better off getting a qualified sparks too look at if - if you don't feel confident with something like this then you could potentially do more damage.

 

[kingeri]

Big drawback of the Edison..........one human error can cost one human life. In fact, lighting itself seems somewhat exempt from the vigorousness of the regs these days....you can't have a screw-terminal connection that is not accessible for inspection, but you can have live terminals exposed with the simple removal of a light bulb. Hmmm..

And you must put a warning label on a CU stating that there is wiring to two versions of BS7671, even though the likelihood is that it will only be opened by a competent person, but no warning label is needed on a fitting where a simple twist leaves live terminals exposed.

 

[grantr37]

Live and Neutral (Line and Neutral) swapped at the wall socket possibly, should have pulled out the plug anyway

 

[monkeyelectric]

When i changed the cu at my new place a few years back there were about half a dozen sockets with the L and N reversed! The house was built in the 80's so it must have been like that for 20+ years!

 

[Swicade]

plug in a 'socket and see' type dubry which will give a good idea if the sockets are wired wrong....if they are wrong then safest thing is to get a sparks in to go through the system. If alls good with the sockets it's gotta be the lamp itself.

Thats probably the cheapest and safest way to go about it....unless ofcourse you either already have all the required test meter's or are going to go out and buy some (test meters....not one of those clear plastic tea stirrer's pretending to be a voltage tester).

The 'socket and see' will also be handy to keep for your landscapeing job, as you can easily check a customer's socket outlet before plugging any of your tools in when on site incase they have any underlying issue's.....so not a waste of money at all tbh.

 

[Column79]

So many questions. I would recomend getting a competant electrician too look at the fault. As without the correct equipment you could cause more problems rather than resolving them.

Thanks for the reply mate.

I have the testers and I know how to carry out the tests. It more of a question of which round to do it. The plug is correctly wired so it has to be the socket-outlet, Its only a single. I just need to know that if i correct the terminations on the socket do I need to or should i test the circuit after I made the small alteration, if the lamp is working safety after? I guess I should test the ring if I've change the Live and neutral around in the socket in case the continuity and insulation is impaired by my handy work. Any Ideas?

Thanks,

Regards Column79

 

[JD6400]

From the questions you have asked i am personally with Dillb , you may have the "knowledge" but by your own admission you have not got the confidence or experience .
And it is the lack of these two that will get you that nasty lick !
It sounds like a 5 Minuit job for a trading sparks.
Just ask your self this , if i had gone on a course to operate a 360 digger but only had a couple of hours experience on a machine from a few years ago and i openly admitted i was nervous , would you then send me to a customers house to dig out for a new patio up against the house ?
I would have a job to burn the place down or to that matter kill someone out right if i did drop a ball .

I am sure you could probably manage it , but do you not put more respect on the life's of loved ones than to ask what are some fundamentally basic questions on how to do the job , on a Internet forum of all things .

No offence , it is just a case of knowing your limits at any given time .

And by the way if you look back over my post history you will see that i never just say get a sparks in to do it .

 

[Column79]

From the questions you have asked i am personally with Dillb , you may have the "knowledge" but by your own admission you have not got the confidence or experience .
And it is the lack of these two that will get you that nasty lick !
It sounds like a 5 Minuit job for a trading sparks.
Just ask your self this , if i had gone on a course to operate a 360 digger but only had a couple of hours experience on a machine from a few years ago and i openly admitted i was nervous , would you then send me to a customers house to dig out for a new patio up against the house ?
I would have a job to burn the place down or to that matter kill someone out right if i did drop a ball .

I am sure you could probably manage it , but do you not put more respect on the life's of loved ones than to ask what are some fundamentally basic questions on how to do the job , on a Internet forum of all things .

No offence , it is just a case of knowing your limits at any given time .

And by the way if you look back over my post history you will see that i never just say get a sparks in to do it .

Thanks fro the reply,

Well that's me told lol. Wise words mate.

It's o.k. now I've got someone coming to have a look at it. I just wasn't sure if I had to retest the ring by law after i had changed the netural and live back around in the socket-outlet. I would have thought you would've as standard procedure. My friends an electrician so he is coming round just in case.

Thanks again for the reply mate.

Regards Column79

 

[telectrix]

if 1 socket is wired wrong, i'd polarity check them all, and Zs test after remedials.

 

[JD6400]

I hope he sorts it nice and quick for you .
And thanks for the reply , i never normally get involved in these type of post because the op always gets snotty when they don't like what they hear , but you are obviously the better man !
Please do not be put off from posting again as i like most on here are far more likely to help out if we know the one seeking advice understands what is safe to follow and what may not be in their own situation .

Many thanks

Dave

 

[snowhead]

Have you had a Smart meter installed recently by a not so smart meter fixer?

 

[markc123]

I hope he sorts it nice and quick for you .
And thanks for the reply , i never normally get involved in these type of post because the op always gets snotty when they don't like what they hear , but you are obviously the better man !
Please do not be put off from posting again as i like most on here are far more likely to help out if we know the one seeking advice understands what is safe to follow and what may not be in their own situation .

Many thanks

Dave

+1 buddy. Well said.

 

[Stroppy]

Would be very easy to test the light for correct polarity with a meter or anything that shows continuity. One probe on the edison outer screw, one on the plug's Live pin. If you have continuity with switch either way = wrong polarity! Socket&see the socket, and get a sparks in if necessary.

 

[Column79]

Thanks for the reply


No I haven't mate

 

[trev]

I'm a little worried by you changing over the L & Ns at a socket outlet mate. What was the reason for you doing this? Did you remove the face and see that the terminations were wrong or did you have some other justification for doing this?
I don't want to sound like I'm having a pop at you because that's not my intention.

 

[Column79]

I'm a little worried by you changing over the L & Ns at a socket outlet mate. What was the reason for you doing this? Did you remove the face and see that the terminations were wrong or did you have some other justification for doing this?
I don't want to sound like I'm having a pop at you because that's not my intention.

The wiring in plug was fine but the s/w was off and i got a shock. I've isolated the supply and visually verified the core colours at the terminations. The neutral is in the s/w line. What I wasn't sure about was if after changing them back round would i have to do a continuity test on the whole ring again, and then insulation resistance test followed by the polarity. I suppose i would have to because other sockets on the ring might be non-polarized as well.

 

[trev]

I'd be looking at the full range of tests on that RFC mate as a matter of urgency.