This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

60A main Fuse, should I upgrade?

Former Community Member
Former Community Member

Supplier main Fuse is 60A and current consumer unit has 80A RCD (61008) as isolator with a notice saying 'Max load not to exceed 80A". Property is one storey with 5 rooms. Currently have 8 circuits, 2 lights with B10s, 2 ring finals with B32s, Cooker with B40, Shower with B40, Water Heater with B16 & Garage feed to a sub board with C40. Want to add a new 10.5kw shower so will need 50A protective device but not sure if should be approaching the DNO for an upgrade of the main fuse as running both showers together alone will draw a decent load

  • You should be getting load approval if adding just one shower if one is not existing I think. Who does these days?  

  • Don't ask us, ask the DNO!

  • Former Community Member
    0 Former Community Member

    ok, thanks

  • I suspect that an upgrade would be needed if both showers are to be used at the same time.

  • or if not, consider a shower priority unit… (especially if the DNO upgrade turns out to be more than just a fuse replacement - e.g. if it's a looped supply)

       - Andy. 

  • I cannot imagine that the DNO will  entertain the idea.

  • Not again! Diversity, time of use etc. Ignore it, if the fuse fails then the DNO may increase it to 80A, otherwise, big bills may be expected if you make a fuss. Failure is very unlikely. A 60A fuse will carry 80A for hours without failure, but you knew that didn't you? See fig 3A3 in the BBB.

  • Former Community Member
    0 Former Community Member

    Thanks David. I'm just starting out and whilst I understand the basis of diversity I was anticipating a high chance that both showers will be in operation concurrently. I take your point on the time it would take and should have thought about that. Would it then be safe to assume the main 60A fuse is likely to be a BS 3036 as this is the only table with a 60A rating?

  • No it will be basically a BS88 type, with similar characteristics. Use the 63A graph. BS3036 fuses are the rewirable type, and whilst still listed are not used for DNO fuses (not for at lease 60 years). The older cartridge types have been replaced with BS88 as the two are very similar, although the nearest rating is 63A. Diversity depends on TIME as well as how many things are in use, it is very badly understood, and I am afraid taught.

  • Is it likely both showers could be used at 5he same time? Apart from the electrical question I cannot see a normal water supply being able to provide enough pressure unless one of them (or both) aretank fed with a pump