Thoughts on 10mm supply with 6mm main earth

[DaveS79]

Hi all hope everyone well.

Interested to clarify my thoughts with others on this. Did a quick inspection of property for a potential consumer unit change. The property is house converted in flat downstairs and upstairs. Main intake is in door entrance. Here as can see from photo supply comes into main head then splits to 3 x 63 amp BS1361 fuses which serves landlords and the 2 flats. Supply from these is 25mm x 16mm earth it then joints in MEM box and supply steps down to 10mm live conductors in metallic pipe to flat and 6mm main earth. Water and gas are both bonded in 6mm also. Have not actually come across a supply in 10mm before so interested if others have thoughts on this set up have checked regs and 10mm clipped direct has 65 amp capacity but has 57amp capacity for reference method B enclosed in conduit. Would of thought as cables run in the mettalic supply pipe this would be the more appropriate rating.

 

[Phoenix]

The meters are located in the flat? right (assume there is another cutout, likely with a solid link local to the meter?) I'd suggest that the conduit and the 10mm conductors are not under BS7671 at all... they belong to the DNO, or rather some mythical entitity they call a BNO as an excuse to not be responsible for stuff they themselves installed decades earlier.

I'd not worry too much if its just a consumer unit change, you can make a note that you reckon its undersized on the supply side if you wish, you are not adding any load, i.e. not making the situation anymore of a problem than it is now. If it however was a new shower circuit you were fitting you might have more of a worry as BS7671 require you to make sure existing gear including that of teh distributor is suitable for the load increase.

Are you sure its 10mm singles, does it look slightly bigger, could be 7/064 depending on age, though if it doesn't look bigger then it could just be 7/052

 

[DaveS79]

The meters are located in the flat? right (assume there is another cutout, likely with a solid link local to the meter?) I'd suggest that the conduit and the 10mm conductors are not under BS7671 at all... they belong to the DNO, or rather some mythical entitity they call a BNO as an excuse to not be responsible for stuff they themselves installed decades earlier.

I'd not worry too much if its just a consumer unit change, you can make a note that you reckon its undersized on the supply side if you wish, you are not adding any load, i.e. not making the situation anymore of a problem than it is now. If it however was a new shower circuit you were fitting you might have more of a worry as BS7671 require you to make sure existing gear including that of teh distributor is suitable for the load increase.

Are you sure its 10mm singles, does it look slightly bigger, could be 7/064 depending on age, though if it doesn't look bigger then it could just be 7/052

Thanks Phoenix. Yes the meter is in the property. There is no other cutout. The mettalic supply pipe runs into another MEM box here, connects into Henley block and from Henley 25mm to meter. Does really look like 10mm compared to 10mm earth i had.