Old cables - Pitch/Compound leaking out

[mrbj]

Hi,
Installation approx 50years old.
Low voltage 230/400V.(UK).
0.5sq in (~300mm2)4core PILC cable.
Cables/Gland Boxes located inside switchroom.
Problem
The black pitch/compound that is used to 'pot' the end of the cable into the cable gland/termination box is leaching / leaking out, and apprears to have been doing so for a number of years.
This is evident by an amount of black pitch running down the side of the cable from the cable box.
The cable is adequate to carry the site load.
There does not appear to be any heat generated at the terminals or within the gland/terminal box, and the cable is cool to touch.
Could this be just natural expansion of the compound during warm/hot weather or something more sinister.
Your thoughts/advice would be much appreciated.
Regards,
mrbj.

 

[Marmite]

It's very common for compound to leak out of cable boxes. Unless there's a big pool of it on the floor there is unlikely to be a problem. In the utility I worked for we used to put sheets of white paper on the floor beneath leaking boxes to monitor the leak over time. Depending where the leak is coming from, you might be able to tighten the nuts slightly, taking care not to shear the studs. If the leak is from a cracked lead plumb then there's not a lot you can do about it other than monitor over time. For substantial leaks the box would have to be broken down and remade. Leaks tend to be very slow in any case because the compound is like solid toffee at normal room temperature.
Regards
Marmite

 

[andybro]

mrbj
Your suspicion about expansion due to hot weather may be justified. We saw exactly the same thing on a number of boxes immediately after the very hot spell (for the UK) we experienced last summer. All of these boxes had been perfectly OK for the previous 20-30 years.
Andybro