How to certify a lighting spur off a socket?

Chrisknowlesuk · Jan 18, 2019

I've just finished a small job replacing a bathroom light and adding an extractor fan.

Since it is a very old installation there was no earth to the lighting circuit.

Part of the job was to remove a fan heater that had been supplied by a socket radial.

To overcome the lack of earth situation I've added a switched spur to the end of the socket radial circuit which now supplies the new lights and fan.

So this circuit now has an earth and is RCD protected.

My question is how to I fill in some of the details on the cert? For example, cable sizing is 1.5mm for the lights but 2.5mm for radial, I'm unsure which figure to put in??

Everything is zoned correctly and more than enough tests have been done etc...

Midwest · Jan 18, 2019

Suppose there would be harm in providing one each, but the only difference would be the cable size & ocpd. The tests (& results)however, would be for the complete circuit.

Cancel that, just re-read your op. I'd just do the one for the new work, the radial is existing.

Baddegg · Jan 18, 2019

Use the smallest 1.5 (worst case cable scenario) for the figures and id also make a note on the cert?

telectrix · Jan 18, 2019

you only need a MWC as it's an existing circuit being altered.

Pete999 · Jan 18, 2019

telectrix said:
you only need a MWC as it's an existing circuit being altered.

Succinct and to the point and what's more important correctamundo, feeling literal this morning.

telectrix · Jan 18, 2019

and full marks to OP for doing it that way some cowboys would have insisted in a lighting rewire.

Intoelectrics · Jan 18, 2019

telectrix said:
and full marks to OP for doing it that way some cowboys would have insisted in a lighting rewire.

Agreed, nice to see someone thinking, being conscientious about safety and looking at cost effective best working practice.
To the OP, tel is correct but there is nothing stopping you doing an EICR for the whole circuit if you feel its required. More info is always better (helps out the person following up in the future) and always note down worst case scenario. Potential faults will not discriminate the will often find the weakest link.