Arcing on gas bond

[jmtisme]

Hi got a problem with a PIR I am doing got small arcing when putting bond on to main gas pipe getting .5v when measured across pipe and bond had gas board out they proved that incoming pipe is in plastic disconnected all earths and still getting it discon earths and neutrals still getting it.

 

[Darkwood]

You are testing between gaspipe to earth while bonding is not connected to pipe i assume to see what voltage difference there is present, although 0.5v isnt very large there could be a large current flowing, have you clamp tested the bonding to gas to see if curent is flowing, also switching off full mains and retesting will confirm if source of voltage is from installation to premises.

 

[jmtisme]

Have clamp tested the main earth bond going into consumer unit there was nothing on it will test the bond now all my tests on this were with main fuse pulled thanks again

 

[malcolmsanford]

An arcing on a bonding condutor could be a a sign of a fault. What system have you got there is it a TNC-S or TT?

You can sometimes get a fault from another property that will track back to your bonding through the TNC_S PME or the TT rod. You say the gas board have confirmed the pipe is plastic, is the water also plastic?

As Darkwood says I would completely isoalte your installation either from the double pole isolator switch, that way you know if your installation is cauisng the problem

 

[jmtisme]

I have isolated the supply and removed bond from water pipe it still arcs. The fault can not be on the installation of the property I am working on. Any more help would be great thanks again guys.

 

[Graeme Harrold]

Isolate all of the earths individually and see if you have any additional (possibly redundant bonds) and see where the induced voltage is comming from. The gas may be source, or it could be the exit path to earth. What does the gas supply?? is it a shared supply, any external circuits e.g. out buildings with connected spike. This is a difficult one to diagnose remotely and all you will get is plenty of well educated guesses and possibly if you are lucky solutions....

If the gas supply is confirmed as being plastic (no path to earth and internal is copper), then there must be a fault on the equipment it supplies.

 

[jmtisme]

Thanks again guys will check today if the gas supply is shared. Should I leave the bond disconnected or would it be safer to have it connected thus grounding any possible fault

 

[Darkwood]

Thanks again guys will check today if the gas supply is shared. Should I leave the bond disconnected or would it be safer to have it connected thus grounding any possible fault

Well i think you answered your own question there.

 

[jmtisme]

Gas service is not shared but water will be shared through copper and this goes through a boiler which is connected to the gas.