I was hoping someone would clarify the requirements for the minimum diameter (on a 100 amp tn-s) earth cable. The cable from the incoming supply to the consumer unit is 16mm.The earth cable from the c.u. to the ring main sockets, lights, shower, cooker etc is only 10mm, is this acceptable?
earth cable diameter oa a 100amp tns
- Thread starter diydamian
- Start date
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kai
The 16sq.mm. incoming cable looks a bit small for a 100amp supply, the rating of 16.sq.mm. cable is around 80 amps at the most in free air!
Check the cables again and re-post. There should be the size printed along the cable somewhere.
Check the cables again and re-post. There should be the size printed along the cable somewhere.
Kai, im sure he talking about the earth cable and not the live conductors.
The earth cable from the supply point to the consumer unit should be 16mm.
The 10mm green and yellow cable(s) taken from the MET which is normally within the consumer unit should go to main incoming gas and water intake positions as main equipotential bonding.
All circuit earth cables are usually contained within the grey/white twin and earth cabling and will range in size from 1.0mm to 4mm depending on the circuits involved and will need green and yellow sleeving within the accessories and within the consumer unit.
the above is all based on a normal 100amp TN system within a domestic property.
The earth cable from the supply point to the consumer unit should be 16mm.
The 10mm green and yellow cable(s) taken from the MET which is normally within the consumer unit should go to main incoming gas and water intake positions as main equipotential bonding.
All circuit earth cables are usually contained within the grey/white twin and earth cabling and will range in size from 1.0mm to 4mm depending on the circuits involved and will need green and yellow sleeving within the accessories and within the consumer unit.
the above is all based on a normal 100amp TN system within a domestic property.
Hi guys, my apoligies, when I read the message back I realised i wasn't being clear enough 
The meter tails are 25mmsq. The earth to the consumer unit is 16mmsq. The earth from the c.u. to the gas and water pipes in the cellar is 10 mmsq. The earth used for cross bonding the pipes and radiators in the rest of the house is 10 mmsq. The earths to the sockets are in the 2.5mmsq twin and earth cable and the lights are 1.5mmsq twin and earth cable. My main concern was the cross bonding cable size, is 10mm ok if the c.u. has a 16mm earth supply?
The meter tails are 25mmsq. The earth to the consumer unit is 16mmsq. The earth from the c.u. to the gas and water pipes in the cellar is 10 mmsq. The earth used for cross bonding the pipes and radiators in the rest of the house is 10 mmsq. The earths to the sockets are in the 2.5mmsq twin and earth cable and the lights are 1.5mmsq twin and earth cable. My main concern was the cross bonding cable size, is 10mm ok if the c.u. has a 16mm earth supply?Sponsored Links
The main bonding needs to be 10mm to gas and water which you say it is, so that is correct.
the cross bonding which you also say is 10mm is oversized actually, they do not need to be bigger than 4mm nowadays, and perhaps not even needed at all. Cross bonding as per 16th editionis not needed at kitchen sinks, radiaters etc other than special locations which are normally in a domestic premises the bathroom/shower rooms.
But no big harm in the cross bonding being in place.
With the sound of your installation you have nothing to worry about. The only concern i would have with your premises is theres probably no supplementary bonding in the bathroom/shower rooms connecting your metal pipework and the circuits within those rooms which is a recently new reg.. But you only need to upgrade and install this bonding if you carry electrical work out int hese locations or change the consumer unit
the cross bonding which you also say is 10mm is oversized actually, they do not need to be bigger than 4mm nowadays, and perhaps not even needed at all. Cross bonding as per 16th editionis not needed at kitchen sinks, radiaters etc other than special locations which are normally in a domestic premises the bathroom/shower rooms.
But no big harm in the cross bonding being in place.
With the sound of your installation you have nothing to worry about. The only concern i would have with your premises is theres probably no supplementary bonding in the bathroom/shower rooms connecting your metal pipework and the circuits within those rooms which is a recently new reg.. But you only need to upgrade and install this bonding if you carry electrical work out int hese locations or change the consumer unit
What possible grounds have you got for thinking this is "probably" the case??StirlingScott said:
diydamian said:
But if there is no s-e-b, you should not leave that situation until some other activity forces you to rectify it...
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