Old rubber and stranded cables

[230volt]

Hi guys,

A customer wants an old re-wireable consumer unit upgraded.

Wiring is extremely old probably 1940's. Of the two power circuits, one is the old rubber cable and one is the old red and black stranded cable.

IR tests show ok L-N L-E N-E.

Problem is the cables have no cpc on the consumer unit side. I'm getting good zs on the sockets which are twin and earth radials on the socket end (so cables must switch via a jb or something under floorboards maybe).

But I have no idea where they are picking up an earth and there is no metal conduit either.

Should I go ahead and change the unit and sign it off even though I cant put the r1+r2 readings in because there is no cpc in the consumer unit?

 

[7029 dave]

Yes as said rewire in need, just to note,with old imperial rubber cables,may look all okay visually, until you start pulling them about and watch the insulation just fall off.

 

[230volt]

Thanks guys

As I thought, I'm not touching it.

Just phoned her to tell her it would need to be full re-wire or I cant do anything.

 

[ferg]

Thanks guys

As I thought, I'm not touching it.

Just phoned her to tell her it would need to be full re-wire or I cant do anything.

Good call.

 

[PEG]

In a lot of older installations ,the CPC was run directly from the main earth Isco , possibly in an unsheathed cable and possibly served a few circuits , just teeing of where ever necessary

Good call,seen plenty like this,where above,maybe a modern looking semi-rewire...and below,t&e cpc arrive at a JB,and leave via an ancient un-sheathed copper conductor.

Spiders' web under floor,joined together,wrapped round a nail/screw on a joist...

Some have given better than expected readings,when tested...although, a decent fault of fair duration,would anneal it some :ihih:

 

[Risteard]

In a lot of older installations ,the CPC was run directly from the main earth Isco , possibly in an unsheathed cable and possibly served a few circuits , just teeing of where ever necessary

I think some people referred to it as a clothesline (although having looked I have been unable to find a reference for this term).

 

[230volt]

She gave in, in the end and I started re-wiring it today.

 

[7029 dave]

She gave in, in the end and I started re-wiring it today.

Good so she pulled a rabbit out of the hat then.?