submain

[Steve]

My mother has a submain in her house (ok i fitted it in a rush as a bodge job).

It is run in 10mm cable, with a B50 protective device.

The submain supplies one 9.5kw shower on a B45, and the upstairs lighitng circuit. The lighting circuit wasnt planned for, but its only a very low load (all CFLs and LEDs).

Is there supposed to be an additional earth cable back to the MET? The source is TNCS.

What happened was the bathroom was replaced and totally refurbed. There were cables not in safe zones in there. These supplied the lighting circuit and the 2-way for the landing light. They were simply cut off and abandoned, the supply for the upstairs lighting circuit now coming off the submain on a B6. This was done by a spark I hasten to add.

I am going back there to rewire the landing light - someone has put a chase up the wall in the landing to take this cable, but never got round to actually throwing in a cable. While the chase is open I thought I'd find out if the submain needs additional earthing besides the CPC of the 10mm.

Cheers.

 

[automationman]

The shower sounds reasonably ok but are you saying you have a lighting circuit protected (unprotected) by a 45 amp CB?
that sounds more like a final circuit to me than a sub-main.

A sub-main usually feeds a distribution board which then feeds final circuits.

The shower sounds reasonably ok but are you saying you have a lighting circuit protected (unprotected) by a 45 amp CB?

Edit: I missed the 50amp protecting the 10mmm, OK so its a sub-main but you wired it originally with the lighting circuit hanging off a 45 am device? That was a very unwise thing to do. You should get a registered electrician to look at the whole thing.

 

[Spark123]

The CPC in the 10mm is fine providing it isn't being used to supply main protective bonding.

 

[Steve]

that sounds more like a final circuit to me than a sub-main.

A sub-main usually feeds a distribution board which then feeds final circuits.

The shower sounds reasonably ok but are you saying you have a lighting circuit protected (unprotected) by a 45 amp CB?

NO, there are two MCBs in the submain CU - a B45 and a B6.

 

[Steve]

The CPC in the 10mm is fine providing it isn't being used to supply main protective bonding.

Cheers, its not being used for bonding of any sort. Mum and dad are away so thought I'd sort this, its been like this since october. She says she's phoned 3 local sparks and nobody wants to touch it because they didnt start it. The spark that did the bathroom lights is working on a big job miles away and cant get back.

 

[Spark123]

So he hasn't been abducted by aliens then

 

[ricicle]

One small inconvienience - if the shower faults the 45A mcb might not discriminate with the 50A so you might lose your lights if you were showering at night. (Slim chance I know)

 

[Steve]

I know about that. Might see about fitting an EM light in the bathroom.

 

[londonboy]

I know about that. Might see about fitting an EM light in the bathroom.

How about the small LED EM fittings, someone has posted on here before I think.

 

[Steve]

I think it was RF, he fitted them in his house.