Hi, having read numerous varying opininions on cable ratings for Electric Shower installation, could someone please advise best course of action for the following:-
MK Sentry 14 way CU with 45A mcb connecting 6mm T&E via a 4 meter run under floor above CU (no conduit, through joists) last metre of run being inside uninsulated stud wall to Isolator switch within cupboard, then 1 metre approx of 6mm T&E to shower fixture (now defunked Heatrae Sadia 7kw). I was initially going to install a replacement Triton 8.5Kw for ease of install, but having read many posts on here about published figures of heat output dependant on voltage factor used (230 or 240V) I decided to investigate further and visit Creda and Tritons websites to see what their minimum requirements were for each of their range of wattages. Both manufacturers stated that their 9.5Kw showers could be installed using 6mm or 10mm cable with runs up to 27 metres for the 6mm on a 40A B MCB (usual caveat for thermal insulation etc.). Interestingly Creda give the outputs of 9.5Kw / 8.7Kw 240V / 230V for their 9.5Kw shower.
Having just metered the incoming supply here, there is bang on 240V (used to be 244V) so using figures quoted is it safe to say the amperage isn't over the 40 mark and is safe to use the 6mm cable as already in situ for a 9.5Kw shower given that the cable run is so short, or is it still best to err on the side of caution and install an 8.5Kw? As an aside, the water is supplied via rising main and as such is reasonably good pressure. I live in the same street and have a 10Kw setup with no water pressure issues (installed on 10mm!!!!!).
Many thanks in advance for your input.
MK Sentry 14 way CU with 45A mcb connecting 6mm T&E via a 4 meter run under floor above CU (no conduit, through joists) last metre of run being inside uninsulated stud wall to Isolator switch within cupboard, then 1 metre approx of 6mm T&E to shower fixture (now defunked Heatrae Sadia 7kw). I was initially going to install a replacement Triton 8.5Kw for ease of install, but having read many posts on here about published figures of heat output dependant on voltage factor used (230 or 240V) I decided to investigate further and visit Creda and Tritons websites to see what their minimum requirements were for each of their range of wattages. Both manufacturers stated that their 9.5Kw showers could be installed using 6mm or 10mm cable with runs up to 27 metres for the 6mm on a 40A B MCB (usual caveat for thermal insulation etc.). Interestingly Creda give the outputs of 9.5Kw / 8.7Kw 240V / 230V for their 9.5Kw shower.
Having just metered the incoming supply here, there is bang on 240V (used to be 244V) so using figures quoted is it safe to say the amperage isn't over the 40 mark and is safe to use the 6mm cable as already in situ for a 9.5Kw shower given that the cable run is so short, or is it still best to err on the side of caution and install an 8.5Kw? As an aside, the water is supplied via rising main and as such is reasonably good pressure. I live in the same street and have a 10Kw setup with no water pressure issues (installed on 10mm!!!!!).
Many thanks in advance for your input.