Earth Bonding

[piz]

Hello all
just wanted to check earth bonding to a gas pipe
the con unit is in the flat the gas meter is the other side of the upstairs flat on an outside wall
about 18 meters from con unit is 10mm earth still ok?

also if a lighting circuit is run in steel conduit and it is using the earth for protection is this ok?
I was on the understanding each circuit should have its own cpc

The lighting circuit is in conduit but if I attach a cable and pull and the cable snaps I wont be able to expose the cable again cant cut in to the ceiling (Strucutal)customer dosent want trunking or false ceiling
do I just put a note on con unit warning only class 2 equipmeant to be used Nic sell them
problem is how do I do R1 connect phase to conduit it reads 165ohms way out
any ideas please

 

[Guest123]

10mm for the gas bond is fine.

Have you done a Zs measurement on the lighting circuit???

Sounds like the joints in the conduit are corroding and the continuity resistance is getting higher.

A new CPC may be needed if this is the case.

 

[piz]

Hi Lenny confused on the zs do I measure the conduit as earth
example where do I put my earth clip it taking zs from ceiling rose sorry if it sounds dumb never had conduit issues before

 

[Guest123]

Hi.

Yes IF the conduit is the earth there should be an earth lead bolted onto the back of the conduit box and terminated at the ceiling rose.

How is the conduit terminated at the DB??? is it a metalclad one???

 

[piz]

dont think ther is one the cables come from the lighting circuit to con unit 3 live 3 net no earth
sockets have 3 lives 3 net and 1 earth going to a conduit box in the ceiling
would it be easy to pull cables through to re wire they seem to go in to ceilin g by about 2/3 inches

 

[pushrod]

sounds as if you are effectively dealing with a lighting system with no cpc unless you can find and correct the reason for the high R2.

you might want to have a read of THIS if you are not already familiar with it.

 

[pennywise]

If the Zs readings are Ok metal conduit can be used as the CPC, The NIC advise that a visual inspection of ever light point and switch drop to verify that the fittings and accessories have been correctly connected to the conduit system as Lenny mentions with fly leads.

 

[gizmo]

Silly questio, but you're assuming that the live or neutrals will snap if you pull them, you tried poking a draw wire down the tubes at all yet ?

 

[piz]

No Not yet but was thinking about that I was thinking if I taped a new cable to the old one and it got disconnected I would have lost the circuit