Possible problem with supply earth connection on TN-S system

[Jim_e_Jib]

Long time reader, first time poster.

We moved house about a year ago and had an EICR carried out before purchasing. Everything checked out fine but with a some C3 recommendations for improvement.

The power supply to the house comes up through the floor in the cupboard under the stairs. Recently I was fitting some lino in the cupboard and noticed something oil like running down the lead sheath of the supply cable. On closer inspection, the oil seemed to be running down under the soldered joint for the earth connection and onto some black cloth tape below. I gave the earth wire a gentle wiggle and whole joint rotated on the lead sheath.

It appears it is still making enough of a connection to give a good earth and pass the testing done for the EICR but it doesn't seem right. Is this something normally seen and if not, is it best to contact Western Power?


Any advice gratefully received!

 

[telectrix]

yes contact DNO. that needs cleaning up and the earth connection re making.

 

[Jim_e_Jib]

Thanks for the advice - I'll get on to them!

 

[The Ghost]

And..errr I wouldn't wiggle anything while you are waiting for them keep well away, that oil may be tar that is sweating out from heat on the supply cable.

 

[Jim_e_Jib]

Thanks Vortigern, I'll resist the temptation!

 

[The Ghost]

Well I hope you have phoned them?

 

[Jim_e_Jib]

I spoke to someone on their instant chat, they could send someone out within fours hours tonight but suggested I might like to contact them again tomorrow so they could arrange a visit at a more sensible time.

Out of interest, was the tar used in the construction of the cable or perhaps used as a sealant?

 

[Pete999]

Long time reader, first time poster.

We moved house about a year ago and had an EICR carried out before purchasing. Everything checked out fine but with a some C3 recommendations for improvement.

The power supply to the house comes up through the floor in the cupboard under the stairs. Recently I was fitting some lino in the cupboard and noticed something oil like running down the lead sheath of the supply cable. On closer inspection, the oil seemed to be running down under the soldered joint for the earth connection and onto some black cloth tape below. I gave the earth wire a gentle wiggle and whole joint rotated on the lead sheath.

It appears it is still making enough of a connection to give a good earth and pass the testing done for the EICR but it doesn't seem right. Is this something normally seen and if not, is it best to contact Western Power?


Any advice gratefully received!


View attachment 39207 View attachment 39208

As Tel said contact the DNO and get that mess looked at, the bloke that did the EICR? did he not mention this to you on the certificate?

 

[Jim_e_Jib]

Hi Pete999, thanks for the advice. It wasn't mentioned on the EICR but that was done about a year ago, before we moved in, so I couldn't be sure what condition it was in then.

 

[Pete999]

Hi Pete999, thanks for the advice. It wasn't mentioned on the EICR but that was done about a year ago, before we moved in, so I couldn't be sure what condition it was in then.

I see, but even so that earth connection must have been like that during the EICR and should have been sorted at that time. Hope you get it sorted soonest Jim.

 

[telectrix]

time to get the blowlamp out.

 

[Jim_e_Jib]

I've got an old Primus paraffin blowlamp - time to dust it off, it should generate more than enough heat..... If only the matches weren't in a drawer with a childproof lock on...

 

[The Ghost]

If I understand this correctly, and looking at your picture of the earth...There appears to be heat damage to 1: the earth connection and 2: the supply cable insulation. When that "tar" starts to run it indicates heat in the supply cable. Which may in turn start to melt the solder on the earth connection to the sheath of the TN-S supply cable. If that really is the case (worst scenario!) hard to tell from here, then I would not delay getting the DNO in.

 

[Jim_e_Jib]

Thanks Vortigern. I've arranged to leave work early today and will call the DNO when I get home. They said they couldn't make an advance booking for this type of job and to call when someone would be in the house for the four hour window.

I'll let you know how it goes!

 

[Percyprod]

I used to get called to a lot of these when working for dno. Usually nothing to worry about. It is bitumen which used to bu used to fill the termination chamber on the old cut-outs. When the cut out was changed most of the bitumen is removed, but it can start to run out of the cable, more messy than dangerous. Dno will check and clean up, but not much else can be donee. They will also re-terminate earth cable.

 

[Jim_e_Jib]

Top marks to Western Power - two engineers were here a couple of hours after I rang them this afternoon. The lead has been cleaned up, a new earth connection has been made and some sealant used to stop any more tar weeping out.

 

[Jim_e_Jib]

Thanks Percyprod, looks like we were posting at the same time!

 

[telectrix]

that connector should have been fixed to the wall or the weetabix board and a 16mm gn/y conductor to replace the bare conductor to the CU/MET.

 

[Jim_e_Jib]

Hi telectrix, thanks for this - it seems Western Power have just lost a few marks...

Is it something I should ask them to come back to do or is it more of a good practice thing?

 

[Deleted member 26818]

Was the original Earth soldered to the sheath of the cable, or to a constant tension spring clamp?