Sticky line running up wall from sockets and switches?

[HappyHippyDad]

A customer has asked me to add some sockets. Whilst there she asked if I new what the lines running up the wall from her light switches and sockets were. They are slightly sticky to the touch and this is not recent work it has been in situ for some time.

The picture with the light switch to the left of the door is not great but if you look slightly above the door frame vertical to the switch you can see the mark.
The pic with the socket in shows the socket in the skirting board and you can see the clear vertical mark higher up by the side of the door.

Cables getting warm? Strange filler used? No idea!

 

[Midwest]

Rusting capping or capping reacting with wall finish. What sort of plaster is it?

 

[KEV 1 N]

Have you loosened any accessories off to check the cables? It may be green goo (early pvc insulation starting to degrade) search on here for green goo. It may be "sweating" through the plaster?

 

[Loki]

Plastisizer migration? where the plastic reacts aganist the copper?
As above have you checked for green goo?

 

[Midwest]

Never seen the green goo coming out through the wall, normally gloops out of accessories, but worth a butchers I suppose.

 

[Octopus]

chase not deep enough and / or plaster too thin.

 

[mhar]

To aid people who don't know where the safe zones are?!

 

[davesparks]

My guess would be it’s the cables only being covered by a layer of paint, which has remained sticky because some paints never go off properly when applied to cables.

 

[HappyHippyDad]

I think the last suggestion by Dave (and Murdoch) sounds most likely. There is a slight bulge in certain areas of the chase where they had not buried it deeply enough. Also there was no sign of the green goo in the socket.

 

[Strima]

That looks like quite an old property.

Is there lime plaster on the walls?

Lime plaster could be reacting with cable that had the plasticiser in that causes green goo???

 

[ruston]

Some old oil based paints will do that if they can't be absorbed into the plaster .
If silicon has been use , even in small quantites paint will not take to it.

 

[l4urence]

The lines only appear where the cable runs are. I’m thinking that a different plaster / filler was used for these runs which were added after the original plastering was done. If not then something is reacting - earlier capping corrosion advice seems good as is plasticiser reaction. I would be tempted to take some plaster out where the lines are and see what’s up.

 

[ruston]

Yes , damp , condensaton and corrosion could cause that , esecially where the trunking has been penetrated by clout nails /fixings.
Scrape the least conspicuos one out and hopefully all will be made clear.