What length of cable would you say is ideal for the twin and earth the back box of lighting and sockets etc? Too long means the cable gets in the way. Too short makes it difficult for a visual inspection etc. Thanks.
Length of cable in back box
- Thread starter chriselevate
- Start date
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A length less than too long.
I don't think a visual inspection is the relevant factor.
They have to be connected to the accessory in the first place.
It depends where the cable enters and where the terminals are.
I allow just enough that each conductor can reach any possible accessory terminal location in the box.
After removing the outer sheath from the cable, I draw the wires to the centre of the box, then bring them straight out, and cut them two inches from the surface of the wall.
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Thanks. That gives just about the right amount then?
While you wrote "length of cable", do you mean the length of the insulated conductors after the point where the cable sheathing is removed?)
("two inches from the surface of the wall". Before or after you strip the insulation?
I cannot see how you could possibly terminate any device in a wall-plate with such a short length of wiring.)
50 mm (two inches) seems to me to be much too short.
UK readers may not care but North American regulations require that the length of such insulated conductors be not less than 6 Inches (150 mm), and I agree with that.
I generally leave about 125mm-150mm to play with from the entry point, if side, bottom/top. If middle a little less. As not all terminals are located in the same position in different branded/manufactured accessories, this leaves some scope for change. But I do generally fit 35mm backboxes, so normally plenty of room for slack.
I'm glad he has asked actually, far too many DIYers cut the wires far too short, which makes replacing an accessory a nightmare.
I'd like to think the op is attempting to do his electrical work to professional standards.
I think if a wire is long enough to have it's end re-stripped say at least three times in it's life, then it can't be too bad.
if the cable comes in to a double sized box from a corner, I allow the cable to reach to the far side, and cut it there. Then strip the outer sheath as far as I can.
Seems to leave plenty of slack to arrange the conductors, and allow for any faceplate design changes in the future.
Seems to leave plenty of slack to arrange the conductors, and allow for any faceplate design changes in the future.
Read his question again:
It makes no sense that someone who is aware that having too much can cause problems as can having too little hasn't worked out for himself that getting close to the upper bound is desirable and has found out from installing accessories where that upper bound is.
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I find that if the front plate is an RCD one there is very little room for wires behind (due to the amount of gubbins on the plate) so the lengths have to be exactly what is required.
Different brand front plates seem to have their connections in slightly different positions so so the length depends upon the front plate.
Different brand front plates seem to have their connections in slightly different positions so so the length depends upon the front plate.
All that is true, and it has the following implications:
- The person installing it at the time will be able to determine what is needed, nobody else.
- No general rules-of-thumb/common opinions of others are of any value.
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