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Pete

Safe zone for cables

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Quick question on cable safe zones. I realise that the cable must be in a safe zone 150mm or buried at least 50mm from the surface. I have a service void in my frame which has created a 40mm space at the bottom of the wall which when plasterboarded will be 55mm (ish) so would it be acceptable to run  my cables in this area which would be behind the skirting board or do I need to run the cables as you would expect in line with the sockets? The service void is filled with 40mm rockwool so it would save me drilling all the studs and making a gap for the cables. This will only happen on an exterior wall of the timber frame. TIA

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No. That's not a safe zone.  Run the cables in proper safe zones in the service void you have.

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2 hours ago, Pete said:

...l so it would save me drilling all the studs and making a gap for the cables. This will only happen on an exterior wall of the timber frame...

 

I can't understand your rationale here. In most TF constructions, the TF is boarded out internally to form the airtightness barrier and then it is battened out over the TF uprights to form the service cavity.  I know that you have the airtightness layer at your ceiling in your single storey section, so you can't run your ringmain around the roof void without risking compromising your airtightness.  But way is wrong with drilling through the studs just below the ceiling level if you need horizontal runs and using the service cavity for your services?  Or even run them horizontally at switch level.  Wherever they are they should be taped or clipped back to run 50mm from the surface.

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26 minutes ago, TerryE said:

 

I can't understand your rationale here. In most TF constructions, the TF is boarded out internally to form the airtightness barrier and then it is battened out over the TF uprights to form the service cavity.  I know that you have the airtightness layer at your ceiling in your single storey section, so you can't run your ringmain around the roof void without risking compromising your airtightness.  But way is wrong with drilling through the studs just below the ceiling level if you need horizontal runs and using the service cavity for your services?  Or even run them horizontally at switch level.  Wherever they are they should be taped or clipped back to run 50mm from the surface.

Due to the nature of our build which involves a 500mm cantilever I cannot get access from below as I would have to go outside the thermal envelope of the building as well as the airtightness layer. I cannot take the cables right round the room due to floor to ceiling windows so instead of an easy cable run it involves a lot more drilling it would seem. 

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I run cables around the room at socket or light switch height. As long as there is ONE accessory on the wall at that height, it is a safe zone for the entire wall.  If you need to get past a window, go down to socket level and across in that safe zone. If there is no safe zone there, go up to the 150mm ceiling safe zone.

 

As a matter of course, all my service void battens have gaps at socket and switch height.  I have tried many times to get joiners to pre drill them, or even as I do just leave a 1" gap, but none will ever do a simple thing to make it easy for the next trade.

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Going horizontal between sockets saves cable.

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