Adding an exterior light

[terryplumb]

Looks like that's been installed to protect a dedicated circuit for a shower.
Do parents remember that getting done ?
If you turn that RCD off ,I don't suppose it switches off all the other circuits in the consumer unit ,by any slim chance ??

 

[Jupiter01]

I will check tomorrow and get back to you. Really appreciate your input.

 

[Jupiter01]

The RCD only controls the electric shower in the bathroom. This was put in around 12 years ago when they renovated the bath.
It doesn’t affect the other breakers.

 

[flameport]

Any additions will require an RCD, both for the cables in the wall and the fact that it's supplying a light.

 

[Jupiter01]

Does that mean an FCU for the light will not suffice?

 

[Jupiter01]

Can I use this to operate the light via a plug?

 

[Jupiter01]

Also provide a two pole isolater ( Live and Neutral ) to provide a means to fully isolate the lamp in the event it gets damaged

I've never used one of these and will now make these my default.

Can I please ask, if I was using a regular FCU, and running something of this, is it always safe to work on this "something" when the FCU is switched off?

Similarly, when working on a light fitting, which just has the switch wire in the ceiling, is it always safe to work on this with the switch in the off position?

With both of these, I will take extra precautions to ensure they wont inadvertently be switched on and I would as a matter of course use my 2 pole tester.

Your comment on Neutral has raised some doubts for me. Thanks for your help.

 

[bernardgreen]

Can I please ask, if I was using a regular FCU, and running something of this, is it always safe to work on this "something" when the FCU is switched off?

Not always 100% safe, correct use of the two probe tester will make it almost 100% There is a risk that someone else might turn the FCU back ON while you are working.

If the switch in the FCU switches both Live and Neutral then you are 99.9% safe from electric shock. The 0.1% is when there is an error in the wiring such as a sneak circuit or similar that by-passes the isolation. I once found a lighting circuit with two switches, one switch connected the lamp to one MCB, the other switch connected the lamp to a different MCB

If the switch in the FCU switches only Live and not Neutral then you are 99.8.% safe from electric shock with the above 0.1% still applicable. The other 0.1% is the risk that the Neutral may not be at Ground potential due to a broken Neutral

The main "danger" with the Neutral still connected while you are working is that the Neutral touches something that is Earthed and this trips the RCD which could leave you and other people in the house in darkness.

 

[Jupiter01]

Thanks for the clarification.
Presumably 100% safe is to switch all electricity off from the mains?

Based on the logic above, anything short of this will have a safety rate below 100%? Clearly, switching everything off isn’t always practical. Is there an acceptable risk? I.E. FCU switched to off, Breaker for that circuit switched off, etc.

Clearly, with each of these I’d expect a 2 pole tester to be used.

 

[Jupiter01]

Hi All,

can someone please advise on my last post please. I want to make sure I understand the point made by @bernardgreen.

Also, can I stick this flex cable on my light and a 3 pin plug on the other end to operate via a Electrical socket?

Thanks again

 

[Taylortwocities]

Yes, with a 3amp fuse in the plug.

 

[Jupiter01]

Thanks for the clarification.
Presumably 100% safe is to switch all electricity off from the mains?

Based on the logic above, anything short of this will have a safety rate below 100%? Clearly, switching everything off isn’t always practical. Is there an acceptable risk? I.E. FCU switched to off, Breaker for that circuit switched off, etc.

Clearly, with each of these I’d expect a 2 pole tester to be used.

Hi, can someone please shed some light on this? I am trying to gauge whether it is suitable to service electrics (with the stated precautions) when a light switch is off (only the switch wire is at the ceiling rose) and the output of an FCU when the FCU is switched off.

Thanks for your help.

 

[Taylortwocities]

No electrical work should be undertaken unless you have carried out safe isolation procedures.
Here is a guide https://dms.niceic.com/archive/0000000011.pdf
and/or
https://www.coolconcerns.co.uk/imagelib/CS14_Safe_isolation.pdf

Note that just turning off a light switch only disconnects the live connection (assuming the circuit is wired correctly). This means that the neutral is still attached to the circuit and this can be energised by any number of other influences. Further, the neutral will still be monitored by any RCD in play, and this may trip if the neutral were to touch earth.

Turning off an FCU should disconnect the circuit, assuming that the FCU is double pole and that it is not faulty.
Follow the safe isolation procedure, practise it until you are familiar with the process. Use it, even if you are switching off the MAIN SWITCH. Everything can fail, electricity kills.

Further. Just turning off a switch is not absolutely safe, a switch turned off can be turned on by someone else. A lock off device provides added security.

 

[bernardgreen]

Presumably 100% safe is to switch all electricity off from the mains?

That is the only way to be 99.99% safe from getting an electric shock when working on the electrics in your house.

Note that just turning off a light switch only disconnects the live connection

between the switch and the lamp. There will still be a Live in the switch and there is likely to be Live wires in the ceiling rose.

 

[Jupiter01]

and there is likely to be Live wires in the ceiling rose.

What's an example of this when there is only one cable in the ceiling rose? Are you raising the possibility of this cable inadvertently connecting to the live at the switch?