Induction hob.
- Thread starter Bogart
- Start date
Help Support Talk Electrician Forum:
Why should it be a wind up is a legitimate question? To clarify is a definite 3 phase supply each phase having its own CU , picture attached. And no there is no main switch to isolate all 3 phases at the same time, might be a good idea to install one.
So what is wrong with installing a 4 pole RCD on this board with a 4 pole isolator adjacent to the hob?
So what is wrong with installing a 4 pole RCD on this board with a 4 pole isolator adjacent to the hob?
You have 3 separate fuseboards ....
so 1 way forward is to replace those 3 fuseboards with a single 3 phase board
nothing else is likely to comply with the regs, nor give a sensible safe solution
So we now have a picture, there was clearly a reason why the distribution was installed as it is at the time.
A bit unusual to find sealed henley blocks on the consumers side of the meter
Now you are changing how you want to use the 3 phase supply you have to change the distribution to enable the changes you want to make, bodging 3 phase is not an option
Yes you could use a 4 pole RCD but how do you link the MCB's providing the overcurrent protection
I think you need to read your regs more thoroughly to understand why you cannot do what you are proposing
A Three phase supply would need a 3 pole , linked , circuit breaker.
Why not stop Part Peeing about and just run a single phase supply ?
Why not stop Part Peeing about and just run a single phase supply ?
whose bright idea was that set-up :shakehead
So what you have is a truly oit of balance 3 phase supply - can you post a picture of the metering please. If you have a 3 phase meter, that set-up is probably costing you money, not a subject I truly understand, but out of balance 3 phase metering costs you more money for the leccy than it should do. If, on the other hand you still have 3 single phase meters, then that isn't an issue, you could 3 phase the hob, not sure that is legal though???
So what you have is a truly oit of balance 3 phase supply - can you post a picture of the metering please. If you have a 3 phase meter, that set-up is probably costing you money, not a subject I truly understand, but out of balance 3 phase metering costs you more money for the leccy than it should do. If, on the other hand you still have 3 single phase meters, then that isn't an issue, you could 3 phase the hob, not sure that is legal though???
most TP meters dont read an imbalance, just the total of each phase
3 single meters isnt an issue either (plenty TP installs metered this way), you could fit a TP board and wire from that. what is an issue is using whats in now, wouldnt be able to take a phase from each board and combine
Can somebody please explain why not, using a 4 pole RCD. All anyone say is you cannot do that please explain why. The hob is just like 3 seperate appliances. The elements are grouped into 3 banks each fed by a seperate live ie phase unless bridged out for single phase use.
for a start, an RCD offers no protection against overload or fault current
the hob is not just like 3 separate appliances. it only has 1 input to it, and the neutrals are usually common
it's just a lot easier to bridge the terminals in the hob and use single phase, connected to 1 board. BY the time you've bought a 4 pole rcd, isolator, and a 3 phase board to fit it in, plus industrial isolator at the hob end , it's going to cost a lot more than using a larger cable. Something like 10mm FTE should suffice an 11 kw hob depending on the cable run, insulation in walls and any other derating factors.
Risteard
Senior Member
Because it's dangerous and grossly non-compliant with the Wiring Regulations as you have been repeatedly informed both here and elsewhere.
The hob is one appliance.
A contactor is not a suitable means of safe isolation.
A single up front 4 pole RCD would not comply with the requirements of BS7671, which is quoted as the standard considered acceptable for utilisation for compliance with building regulations which are law.
As the hob is one appliance it requires a linked OCPD in the supply, this cannot be achieved with 3 independent type A boards.
A contactor is not a suitable means of safe isolation.
A single up front 4 pole RCD would not comply with the requirements of BS7671, which is quoted as the standard considered acceptable for utilisation for compliance with building regulations which are law.
As the hob is one appliance it requires a linked OCPD in the supply, this cannot be achieved with 3 independent type A boards.
- Joined
- Oct 22, 2010
- Messages
- 14,621
- Reaction score
- 1,171
So,today it is an RCBO
yesterday it was an RCD
just saying
yesterday it was an RCD
just saying
Sharpend
"It Just Is"
Maybe he is reading the current regs instead of those of yesteryear?
so that's about £60 in parts just to avoid buying a bit of 10mm cable at roughly £3.50 /m or 17m of cable. Plus you still have to buy cable to run 2.5mm singles in conduit.
If one was not in the trade , one would have to buy 5 X 100m drums of 2.5mm X 6491X .
Brown /Grey/ Bk/ Blu/ green/yell
100m 2.5 mm 6491X is £ 25.63 X 5 = 128.15 + VAT 25.63 Total £153.78
Plus conduit + fittings + 4 pole RCBO + meter tails + 3 pole isolator + 3m of 5 core X 2.5mm Heat resist flex
Jobs a good 'un .
Brown /Grey/ Bk/ Blu/ green/yell
100m 2.5 mm 6491X is £ 25.63 X 5 = 128.15 + VAT 25.63 Total £153.78
Plus conduit + fittings + 4 pole RCBO + meter tails + 3 pole isolator + 3m of 5 core X 2.5mm Heat resist flex
Jobs a good 'un .
Similar threads
