no earth connection

soulman · Oct 21, 2010

hi, just a couple of questions as i'm learning. (3rd yr a college) and a bit confused

If you you were to perform a ZE and find, you had no earth connection at all for example on a tns system. to make the installation safe you install a rod and make the installation a temporary TT system would you then have to install an rcd if for example if was old fuse board with rewireable fuses.

secondly, when performing a consumer change you find the lighting is tripping the rcd, you find its a insulation problem to earth:

1. the lighting circuit put on an mcb and noted at the distrubution board

2. rectify the faulty circuit at your own cost as should have been identified and rectified prior to fitting consumer unit

these are two different answers from two sparks the first answer i thought all circuits were to go on rcd now.

cheers

ianmacd · Oct 21, 2010

No Earth, Call DNO and get them to fix ASAP.

it should never have been energised with a low IR reading so should be fixed before energising or not reconnected.

Ian.

tom1 · Oct 21, 2010

a rod is no good without an rcd

so if you put a rod in then yes rcd it.

Apache · Oct 21, 2010

Yea if you TT it (why temporary - Steptoe will tell you much safer) you MUST have all circuits RCD protected.

Your second question re tripping RCD after CU change. If the installation is in such a bad way that the RCD is tripping due to insulation breakdown it needs to be fixed. You need to get customer to agree to extra remedial work on a CU change, or charge more upfront and do a PIR.

This is not nuisance tripping, the RCD is doing what it is supposed to do. Bypassing it seems not good to me. It's not something that has to be done at your expense! This is why you need a signed contract before work starts! You can't re-energise a dangerous circuit.