I've been asked to quote for a supply to a 'Summer House', clients words not mine. Due to the lay out of the property, it's not practical to supply direct from the CU. There is a socket on a RFC, that can provide a supply via FCU.
Although their garden is quite small, the route for the swa will be about 25metres. So I'm a little concerned about Zs and volt drop. When I went to have a look for the quotation, I discovered a fault on the RFC, no end to end continuity on r1. I'm going back this week to rectify that, so I could do Zs test at the said socket. I will then test at the socket to get a Zs reading, than add to R1+R2 for a suitable sized swa.
I'm happy to calculate the volt drop for the new cable, however I'm not too sure about calculating volt drop on the RFC. I have the calculation;
Ib (design current) x (Mv/A/m) x L (length of circuit divided by four)
1000
As it's an existing circuit, I would be guessing at it's length, although I could obtain a rough estimate via end to end resistance. Am I thinking this out correctly?
Although their garden is quite small, the route for the swa will be about 25metres. So I'm a little concerned about Zs and volt drop. When I went to have a look for the quotation, I discovered a fault on the RFC, no end to end continuity on r1. I'm going back this week to rectify that, so I could do Zs test at the said socket. I will then test at the socket to get a Zs reading, than add to R1+R2 for a suitable sized swa.
I'm happy to calculate the volt drop for the new cable, however I'm not too sure about calculating volt drop on the RFC. I have the calculation;
Ib (design current) x (Mv/A/m) x L (length of circuit divided by four)
1000
As it's an existing circuit, I would be guessing at it's length, although I could obtain a rough estimate via end to end resistance. Am I thinking this out correctly?