main earth is missing

[steviewunda]

Hello I have bought a 1950s house for renovation the supply cable coming in is metal sheathed but has no earth clamp on it.The estate has no overhead supply so for some reason in the past I think the earth has been removed.Can an electrician apply new clamp and test before rewire or would he have to fit earth stake.Many thanks.

 

[dingbat]

Contact your District Network Operator and report it. This is distributor's equipment and an electrician should not really be touching it.

 

[Katron]

Don't know whether this helps but I recently rewired a bungalow, which was a TNS, but there was no earth clamp on the outer sheathing of the supply cable to the consumer unit, phoned up the supplier, an emergency call out was reported and somebody was out within 5 hrs, and was told that the earth was not there responsibilty.......which took me by surprise.....I understood that was the responsibilty of the supplier. Anyway I clamped on a new piece of 16mm back to the board to make it safe......but the customer is now changing it to a PME now anyway.

Katron

 

[daytona]

bottom line is you should get the ze reading from the outer sheath,if you want to put that in a cu you just clamp it and run it in.

 

[Katron]

so it is acceptable to do that

 

[bernardgreen]

DANGER

Putting a clamp on the sheath of an 1950 incommer carries an extremely high risk.. Too loose and it is not going to be an effective earth..

TOO TIGHT and it may crush the insulation inside what is probably a 57 year old cable. Short that out and the district fuse at the substation may blow before the end of the cable by your hand evaporates.

 

[Katron]

There was an existing clamp with a lug, so I was ok, but I shall bear that in mind.

 

[bengasman]

As far as I know the supplier does not have an obligation to supply an earth, strange but true. A bs 951 clamp is NOT an acceptable connector to the sheath to connect the the met. It can damage the sheath or insulation. The fact that. Literally, most houses have an incorrect connection does not make it right. Only the supplier should make a connection to the met. If you short the phase to the substation, you can get ten or twenty thousand amp and that is far from pleasant.

 

[plugwash]

Some DNOs seem to think the use of clamps like that is acceptable.

As for responsibilities the provider is not obliged to provide and earth but if they have provided one they are obliged to maintain it. They are also responsible for safely earthing any metal equiment belonging to them which given that you shouldn't have two seperate earthing systems exposed in the same place means they basically have to either supply an earth or replace all thier kit with plastic.

 

[Softus]

Short that out and the district fuse at the substation may blow before the end of the cable by your hand evaporates.

Did you mean "after"?

 

[bernardgreen]

Short that out and the district fuse at the substation may blow before the end of the cable by your hand evaporates.

Did you mean "after"?

I was being optimistic, quite likely the incomer would have "roman candled" itself into the ground before the sub-station even noticed.

 

[Softus]

OOI, when there is a risk of this happening, how does the DNO engineer mitigate the risk?

Do they (can they?) shut off at the sub-station, or do they just wear thick gloves?

 

[JohnD]

I have seen the kit for working live on overheads, presume it is similar rules for cutouts. Spark-proof visor and apron, gauntlets, helmet. no exposed skin or ordinary clothes. Special boots.

 

[bernardgreen]

Thick 440 volt proof gloves and tools with all but the business end taped up was the kit when they relocated our cut out live.

 

[Softus]

Spark-proof visor and apron, gauntlets, helmet. no exposed skin or ordinary clothes. Special boots.

So, pretty much what your wife wears to bed, John?