Lighting wiring query?

[EricP]

I have just looked at the conservatory lighting in a relatives house, and would appreciate confirmation that it is reasonably compliant as a body has looked at it and is trying to charge the earth to replace it..

The circuit is in 1.0 T&E, taken from a ring main through a 3 amp FCU. The cable runs from the FCU to a wall switch where just the live goes through the switch with the other wires unbroken, and then on to a terminal block in the light point in the conservatory roof.

I hope I have explained it decently. Just one wire from the back of a ring socket into an FCU, on to a switch and then on to the light fitting in the middle of the conservatory roof.

The only point that I can see is that the earth wire is bare at the back of the switch where the insulation has been stripped to switch the live wire, and needs a sheath over it.

Cheers

[David Hansen]

On Tue, 26 Jun 2007 13:29:41 GMT someone who may be EricP wrote this:-

You don't state the reasons why the body claims it should be replaced. They should be able to give these reasons if they have nothing to hide.

Assuming the wires are connected to the correct places, insulation and strain relief are correct, it sounds like it complies with the Wiring Regulations.

I suspect you mean just one cable.

If the cable between the socket and the FCU is 1.0mm2 then it is unlikely to comply, it should be a minimum of 2.5mm2.

That should be corrected with some sleeving.

[meow2222]

Nothing wrong with what you describe. It is not necessary for existing wiring to be upgraded to meet new regulations.

The 1mm^2 run from ring to FCU is compliant with present regs because it is load limited by the 3A fuse at its far end/ middle. But it doesnt matter either way, its not a problem.

Of course this doesnt guarantee there isnt something else amiss somewhere, but what you describe is not reason for any corrective action.

NT

[EricP]

I simply don't know. The relative is an extremely ancient lady that keeps ringing people up "to come and have a look at things". I always arrive after the fact, usually when I see a van leaving, so I work backwards. The body in question is a decent local sparks so it will be kosher. I just wanted to have some confirmation of the situation.

You have kindly confirmed the one point I noticed and provided one other for attention.

Many thanks :))

[John Rumm]

From an overload point of view this is correct, however one also has to also consider protection from fault currents in the event of a phase to neutral or earth fault. Then the question becomes will the cable between socket and FCU be adequately protected by the circuit's protective device in the CU. If the cable is 2.5mm^2, then this is a standard spur configuration and it can be taken as ok, if however this is also wired in 1.0mm^2 then one would have to prove by calculation that it is acceptable in this circumstance. With a MCB in the CU there is a reasonable chance it will still be ok, less so if the CU is the rewireable fuse type.

In reality this is quite probably the case unless the cable to the FCU is long and/or likely to be exposed to risk of damage.

[Phil B]

The cables should be covered to protect them from physical damage eg chair backs rubbing against them. Are they? Phil

[meow2222]

For new installation sure, but this is existing, and fusenpoppen will still occur.

NT

[David Hansen]

On Wed, 27 Jun 2007 03:57:06 -0700 someone who may be [e-mail] wrote this:-

FSVO existing. For all we know the conservatory is one month old.

The question is whether the fuse operates before or after the cable has been damaged by being overheated. Whether it operates or not is a relatively minor question.

[John Rumm]

Its the existing installations which carry most risk. The ring circuit may only have a 1mm^2 CPC, and there may be rewireable fuses which do not open as readily as HRC fuses or MCBs.