When having a new house built the electrician run the speaker wires inside the walls for my dvd -home theater system, the problem being he hasn't used colour coded cable so there is no way of knowing what the polarity of the 2 ply cable is, any suggestions for getting round this problem !

Make an circuit (one cable inside the wall and an extra cable outside) and put 1.5 volt battery and light bulb to it. Then just add some red color to the cable endings.

Then again. If you can hear the polarity while using the home theater I guess it does not really matter

Check the cable again, it may not be as obvious as being red and black but you may find that one side has a faint black line (or dashes) or some other distinguishing feature.

Check the cable again, it may not be as obvious as being red and black but you may find that one side has a faint black line (or dashes) or some other distinguishing feature.

Funny enough i just checked the cable before reading this and it's the actual cable that is different colours, one silver and one a brown colour, anyway thanks lads.

I am not sure I would trust the electrician to choose good cable

for such a job.

Just my 2 penneth.