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Hi,
UKPN are installing a new 200A 3PN supply. Their incoming cable is 95mm.
As per the Multiple Occupancy Building recommendation G87 they will only supply the cut out. I now need to supply an isolator and Ryefield (or equivalent).
Looking at table 4D1A 70mm cable will cover me for free air spaced, using rule of thumb I'm thinking 35mm main bonding. But looking at table 54.8 looks like 25mm is fine, did I read this correct?
544.1.1 We do also have PME.
Here's the snag, in my area we only have 2 phases in the street, so you have to over spec the Ryefield by 33% to get your required number of ways. i.e. 9 ways only has 6 usable ways when only using 2 phases.
Normally not a big deal, but I'm tight for space as this is a retro fit.
So here is my thought, is there any reason why I can't bring in L1 and L2 into the Ryefield, then link L2 to L3 in the Ryefield to enable me to use spare ways? To be clear L3 does not exist so I am not joining phases.
My thought is as long as I do not overload cutout there is no problem. UKPN protect their cable with 200A fuse and cutout bus bar is rated at 200A, so I don't see a problem. But am I missing something?
Thanks
Michael
UKPN are installing a new 200A 3PN supply. Their incoming cable is 95mm.
As per the Multiple Occupancy Building recommendation G87 they will only supply the cut out. I now need to supply an isolator and Ryefield (or equivalent).
Looking at table 4D1A 70mm cable will cover me for free air spaced, using rule of thumb I'm thinking 35mm main bonding. But looking at table 54.8 looks like 25mm is fine, did I read this correct?
544.1.1 We do also have PME.
Here's the snag, in my area we only have 2 phases in the street, so you have to over spec the Ryefield by 33% to get your required number of ways. i.e. 9 ways only has 6 usable ways when only using 2 phases.
Normally not a big deal, but I'm tight for space as this is a retro fit.
So here is my thought, is there any reason why I can't bring in L1 and L2 into the Ryefield, then link L2 to L3 in the Ryefield to enable me to use spare ways? To be clear L3 does not exist so I am not joining phases.
My thought is as long as I do not overload cutout there is no problem. UKPN protect their cable with 200A fuse and cutout bus bar is rated at 200A, so I don't see a problem. But am I missing something?
Thanks
Michael