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4mm2 twin and earth cable

Former Community Member over 4 years ago

regarding 4mm2 cable was it ever available in the old colours with solid conductors rather than the 7 strands version? Ive just done a pre - inspection of a property before doing an EICR and found 2 radial circuits fed from 32A MCBS. The cables appear to be larger than 2,5mm2 . I'm going back to inspect this property with a view to reducing the MCB's to 20A if if they are 2.5mm2. I'm also taking a Vernier gauge to measure the cable diameters and compare to reference tables.

The installation is approximately 30 years old but is in very good condition.

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0 Former Community Member over 4 years ago

UKPN:

There has never been a 4mmsq single core cable in UK, When metric first appeared in 1970 wiring regulations 2.5mmsq was single core 1/1.78 (mm), Next up was 4mmsq 7 strand. 7/0.85 (mm)

Aluminium started at 16mmsq.

Copperclad Aluminium, as our fellow member Michael mentioned, turned up in 1974, same sizes/cores/strands as the above.

For wiring regulation buffs its worth noting that in 1974 the late great Electricity Boards used a "special" 2.5mmsq 7 stranded cable for use in their current/voltage transformer work. (A single core 2.5mmsq was not considered practical).

This cable though did make it into the regs, 7/0.67(mm)

Moving on to the 15thed regs, a previous poster has perhaps misread the radial requirements, a 30/32amp cartridge/mcb is backing up a 4mmsq cable, a 20 amp cartridge/mcb backs up 20 amp cables.

But the circuit in question has happily taken care of kitchen loads for many years, so the idea of downgrading the mcb is perhaps not needed in this case. In any event downgrading protection is something we dont take lightly.

Hope this helps

Regards, UKPN

UKPN

many thanks for your comments they are much appreciated.

Stuart
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0 Former Community Member over 4 years ago

UKPN:

There has never been a 4mmsq single core cable in UK, When metric first appeared in 1970 wiring regulations 2.5mmsq was single core 1/1.78 (mm), Next up was 4mmsq 7 strand. 7/0.85 (mm)

Aluminium started at 16mmsq.

Copperclad Aluminium, as our fellow member Michael mentioned, turned up in 1974, same sizes/cores/strands as the above.

For wiring regulation buffs its worth noting that in 1974 the late great Electricity Boards used a "special" 2.5mmsq 7 stranded cable for use in their current/voltage transformer work. (A single core 2.5mmsq was not considered practical).

This cable though did make it into the regs, 7/0.67(mm)

Moving on to the 15thed regs, a previous poster has perhaps misread the radial requirements, a 30/32amp cartridge/mcb is backing up a 4mmsq cable, a 20 amp cartridge/mcb backs up 20 amp cables.

But the circuit in question has happily taken care of kitchen loads for many years, so the idea of downgrading the mcb is perhaps not needed in this case. In any event downgrading protection is something we dont take lightly.

Hope this helps

Regards, UKPN

UKPN

many thanks for your comments they are much appreciated.

Stuart
Cancel
Vote Up 0 Vote Down

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4mm2 twin and earth cable

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