Maximum Demand

[lilman]

Evening all.

I recently carried out a PIR on a flat following a fire in the consumer unit (neutral bar area badly damaged). Someone had fitted a replacement CU and had got things in a muddle hence me being called. The owner wanted a PIR and any necessary remedials carried out ASAP as he had two new tenants lined up.

CU layout as follows - Shower 40A/Water Heater 40A/Cooker 32A/Kitchen sockets and UF heating 32A/Main ring final (inc UF heating to hall, bed and bath) 32a/2 x kitchen sockets 16A/3 x 6A lighting circuits.

Basically I disconnected some of the underfloor heating to bring the total current draw down - Landlord not happy. What to do? Am I being over cautious because I can't be certain of the cause of the fire (as the CU was already changed). Even when I apply diversity the total is around 102A. Anyone been in a similar situation? Any ideas/thoughts?

 

[Lurch]

Bit on the limit, but with a decent board would probably be fine (not that I'm saying you should just connect it all up and hope for the best). I've seen many boards end up in varying degrees of meltedness from poor terminations with minimal loading, you could fit a decent board (MG or similar) and work on the principal that the likelihood of the shower, cooker and water heater being on regularly simultaneously would be pretty rare. Still, if the board, supply and components are rated at 100A then 102 continuous would be worrying.

What is the UFH pulling or what's the floor area it's covering?

 

[Andy™]

what you describe is a loose connection, not overload.

other than the UF heating, and possibly 40A water heater, that load is similar to many houses, and rarely causes a problem

 

[lilman]

Bit on the limit, but with a decent board would probably be fine (not that I'm saying you should just connect it all up and hope for the best). I've seen many boards end up in varying degrees of meltedness from poor terminations with minimal loading, you could fit a decent board (MG or similar) and work on the principal that the likelihood of the shower, cooker and water heater being on regularly simultaneously would be pretty rare. Still, if the board, supply and components are rated at 100A then 102 continuous would be worrying.What is the UFH pulling or what's the floor area it's covering?

UF heating - 40 square metres @ 150W p/m = 6000W/230V = 26A

 

[lilman]

[quote name='Andy