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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> Sealant has attacked eath conductor https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1355997064 Message started by yoggo on Dec 20^th, 2012, 9:51am

Title: Sealant has attacked eath conductor
Post by yoggo on Dec 20^th, 2012, 9:51am

I am in process of replacing a shower - I have exactly same model to fit.

The water pipe and the electric cable (by design) come through a square hole in the back of the shower and a corresponding hole in tiles and plasterboard. I have had to dig out most carefully all the mastic to get at the water coupling. I find that the earth conductor has gone green for a short distance where the white sheath of the cable was cut back and the earth conductor was not covered by green/yellow sheath. Because this effect was buried in the mastic I suspect it's due to chemicals in the mastic. I also suspect, but of course cannot be sure, that the mastic is plumbers mate. The earth conductor has cleaned up ok but I'd like to prevent recurrence. What mastic should I use? Would taping the area with electricians tape stop seepage of solvents in the mastic? or could it be that solvents might penetrate thin plastic tape)

There isn't any slack cable to pull through so that the mastic would only be in contact with outer white sheath of cable.

Title: Re: Sealant has attacked eath conductor
Post by The_Trician on Dec 20^th, 2012, 2:04pm

I would suspect from your description that humidity/moisture transmitted via damp air is the main culprit here although I cannot be certain without actually seeing it.

Is the shower front casing/enclosure fitted correctly and completely watertight?

I would say that any sealant should be ok so long as you read the instructions. Make sure that it is compatible with plastic cable insulation and you should be ok.

TT

Title: Re: Sealant has attacked eath conductor
Post by CWatters on Dec 20^th, 2012, 6:30pm

Copper goes green if there is any sulphur about eg in the form of air polution from cars or burning coal. I don't know if there is any in mastic.

Title: Re: Sealant has attacked eath conductor
Post by big_all on Dec 20^th, 2012, 6:51pm

could be flux contamination from the plumbing side perhaps as in finger contamination if the plumber fitted the electrics perhaps