Replacing a ceiling light

[Alfie25]

Hi all, I've not undertaken any electrical work before but have read up on the very basics of light fittings and am looking to replace a ceiling rose with a more modern light fitting. I've identified the existing wiring including the switched live and dare I say it the whole swap over looks simple (yes, I know, famous last words).

What's concerning me is the safety aspect. Before I attempt the job I will pull the fuse for the lighting circuit but to be sure that the circuit is dead I want to be able to test it. I've read various threads on here and am leaning towards purchasing a 2 probe voltage tester rather than a non-contact tester. How easy are these to use, as I can't find instructions anywhere. I know they have the G38 probes but where are you meant to insert these given that the wiring is pushed deep into the ceiling rose fittings? Obviously you could put the probe in the screw hole but in that case you couldn't check each wire individually as you'd be testing all in the same block e.g. live.

I know that pulling the fuse/switching off the main fusebox is as far as many DIYers go, but I would prefer to have more re-assurance so please excuse the newbie question.

 

[EFLImpudence]

//www.diynot.com/wiki/Electrics:Lighting

I've read various threads on here and am leaning towards purchasing a 2 probe voltage tester rather than a non-contact tester. How easy are these to use, as I can't find instructions anywhere. I know they have the G38 probes but where are you meant to insert these given that the wiring is pushed deep into the ceiling rose fittings? Obviously you could put the probe in the screw hole but in that case you couldn't check each wire individually as you'd be testing all in the same block e.g. live.

That's all you need to do to test for dead.
Probes to:
L & E,
L & N and
N & E.
All should read 0V (or maybe just a few volts)

I know that pulling the fuse/switching off the main fusebox is as far as many DIYers go, but I would prefer to have more re-assurance so please excuse the newbie question.

Very wise.

 

[PrenticeBoyofDerry]

That makes a pleasant change, someone who cares enough to ask about safe isolation procedures!

Don't forget to test the voltage indicator is working before and after tests. Or could get nasty!

 

[riveralt]

For a ceiling rose test I would also add the Switch Live/N/E with switch on.
Since the Switch live may be coming from a different source.

 

[EFLImpudence]

Good point.

 

[JohnW2]

For a ceiling rose test I would also add the Switch Live/N/E with switch on. ... Since the Switch live may be coming from a different source.

Indeed - and with the switch in both positions if one knows, or even suspects as a slight possibility, that 2-way (or N-way) switching could be afoot.

Kind Regards, John

 

[Alfie25]

Don't forget to test the voltage indicator is working before and after tests. Or could get nasty!

Can you advise on a simple way of testing before and after tests?

Oh, and to the poster who said it should read 0 or just a few volts... on the testers I've looked at there doesn't seem to be a readout, just a selection of lights/beeps:

http://www.toolstation.com/shop/p59...=46329831143&gclid=CIiYuuG_8MUCFS2WtAodaQgAjQ

 

[ban-all-sheds]

Can you advise on a simple way of testing before and after tests?

The simplest way would be to get a proving unit, such as this:

 

[JohnW2]

The simplest way would be to get a proving unit, such as this:

What exactly comes out of that unit? - "50 - 690V AC/DC" seems a little on the vague side

Kind Regards, John

 

[ban-all-sheds]

Hmm.

I confess I didn't look too closely at which photo I picked.

700V AC is what their site says. martindale-electric.co.uk/proving-devices-c-253.html

Maybe not suitable for a tester which is expecting no more than about 250V.

Try this one.

 

[JohnW2]

Hmm. I confess I didn't look too closely at which photo I picked. 700V AC is what their site says.

Hmmm from me, too - it's not really obvious how "50-690V AC/DC" means 700V AC!

Try this one. ...

Given that one is proving a device that will presumably be used for testing ~230V AC, wouldn't you prefer to prove it with AC, rather than DC??

Kind Regards, John

 

[PrenticeBoyofDerry]

Don't forget to test the voltage indicator is working before and after tests. Or could get nasty!

Can you advise on a simple way of testing before and after tests?

There are two methods, either be the use of a functional proving unit or by a known live supply. I am personally always more than a little cautious over recommending the latter.

Some voltage indicators can be tested without the use of a proving unit or live supply.

 

[JohnW2]

Some voltage indicators can be tested without the use of a proving unit or live supply.

If I understand you correctly, that sounds rather iffy. The whole point of 'proving' is to demonstrate that the device responds correctly to being connected to an external supply of voltage in exactly the same way as it was going to be (or had been) used 'in anger'. If one relies on it 'self-testing' in some way, IMO one loses the confidence that 'proper proving' provides.

Kind Regards, John

 

[Alfie25]

Just coming back to this, the light I'll be fitting has a simple terminal block for the wiring which (when wired in) is just housed inside the metal 'cup' which replaces the ceiling rose. I say 'housed' but really it'll be just squashed in together in the final stage of fitting the light. Should the terminal block be covered in insulation tape at all?

 

[ban-all-sheds]

No - as long as you wire the connector block properly, i.e. with no bare conductors visible, it will be OK.