Lead cable

[ColinK]

Howzit guys

Please if i can get some info,im busy re-routing an old lead cable for a client,gonna install it in a new board,what would be the easiest way to get an earth off of that cable as there is no earth "they used the lead as earthing in the old days",and i cant run an external earth as it is to far to dig....tx in advance

Colin

[AndyD]

Lead cabling is very difficult to work with. The bending radius's used to be very long, it's very difficult to gland and joint and I'm not sure you can use brass and copper fittings due to it being a dissimilar metal. In the good old days the lead cable would have had a gland or collar sweated on (similar to soldering on a large scale) unless it was an air pressurized cable in which case the termination procedure was far more complicated.

The electrical regs don't specifically cover lead cabling as far as I know but I would say a separate CPC would be necessary for compliance. I would look at installing a local earth spike if trenching is an issue. I would also test the insulation of the cable before you even quote on this job, the paper or cotton insulation that was often used on the conductors is notoriously hygroscopic and old cables often didn't maintain a good insulation value.

My gut feeling would be to install a new cable entirely to avoid future problems but it's your call.

[ColinK]

Ok yeah great tx for the info,I was also thinking to install earth spike buried at least 2m down with coarse salt to get proper earthing....

[bergie]

i use a cable joiner when i have join or gland off those old cables. theres an ex city council joiner in cape town i normally use. they should have all the special tools etc.
incidentally a 2,4 m earth spike here is normally too short. i always install 2x 2,4m on top of each other. spreading short spikes out doesnt seem to work.i need to get to the water table in this sandy ground.

[AndyD]

incidentally a 2,4 m earth spike here is normally too short. i always install 2x 2,4m on top of each other. spreading short spikes out doesnt seem to work.i need to get to the water table in this sandy ground.

I just installed an earth spike in the southern suburbs of Cape Town and we needed 7 x 2.3 meter spikes on top of each other to get a decent reading.

[bergie]

thats deep.the customer can share the cost with somebody in china.
i found out how the suburb of ysterplaat got its name.theres a impenetrable plaat of yster about a metre deep. not nice for earth spikes.

[AndyD]

I tested with each spike that went in and was sitting with >1000Ω after the first two spikes

[mikilianis]

What about a earth mat

[murdock]

what about the suppliers earth?

in durban the supply earth is considered adiquate

[Sparks]

A clamp around the cable would work, as AndyD points out, the bottom line is: Earth Continuity Reading.