Induction Hob Installation

[Neilpick]

Hi

I'm looking to install a new induction hob rated at 10.8kw that I calculate at circa 46 amps. I can get a new cable from consumer unit to hob location (approx 3m run) and have slot on consumer unit. Have the following questions:

1. Can I apply diversity to this type of hob thereby giving a current rating of approx 21amps and allowing me to use 6mm cable and a 32A breaker or do I ignore diversity and go for a higher breaker / 10mm cable?

2. Do I need to use RCD side of consumer unit or none-RCD side? The way I understand things is that if I connect hob using a combined 45A cooker switch / socket I use the RCD side but if I use just a cooker switch only without the socket, I can use the non-RCD side? ( my spared slot on the CU is on the non-RCD side)

many thanks

 

[RF Lighting]

No you can not apply diversity to induction hobs in the same way as a traditional cooker circuit.

A 50A supply should be installed.

How is the cable to be run? Will any of the cable be concealed within a wall or partition at a depth of less than 50mm?

Which part of the UK are you in?

 

[Neilpick]

Cable will run down from consumer unit, under floor then up a stud partition wall that is behind kitchen units on one side and under stairs on other to the switch. Then back down same stud wall under floor again to a centre island where hob is located. I'm in Scotland.

 

[Taylortwocities]

There's electricity in Scotland? Blimey!
You'll be wanting independence next…. \

 

[EFLImpudence]

No you can not apply diversity to induction hobs in the same way as a traditional cooker circuit.

A 50A supply should be installed.

Have to disagree with you here.
Induction hobs are more efficient therefore use less power.

Using full diversity it will be 21A on a 32Acircuit - 50% tolerance.

However, if you consider unacceptable then fit a 40A MCB (method C).
Surely a mere 5A diversity is acceptable.

 

[ericmark]

I have an induction cooker with max power rated at 10466 - 12455 W but manufacturer states use 32A supply not 54A.
For the hob part alone 7.4 kW is the max as although rings rated at 2.2 kW to 3.7 kW they are paired so can only use that maximum if the other ring of the pair is not used. So although simple maths may show 11.9 kW that can't in real terms be used.
Also whole point of induction is heat goes directly into pan very little is wasted so unless fitted in a soup kitchen with 4 pressure cookers used together the time for max current draw is very limited.
Auto boil and simmer means the idea of having four pans boiling away full chat has gone as one would set the simmer temperature as it is switched on and even unattended it will auto drop to simmer when boiling has started.
We have noted the kitchen is much cooler since we got the induction cooker as less heat is wasted it is also dryer as far less steam is produced my father-in-law has a house with same build next door but one and humidity in our kitchen is around the 50% and in his 75% and he is only cooking for one but on gas.
So read the manufacturers recommendations but would not expect to see any more than 32A is required for whole hob unless very special.

As to RCD that is dependent on cable used and how installed. Surface cable with no socket can be non RCD but if buried less than 50 mm in wall then standard twin and earth will need RCD protection. Using Ali-tube or SWA you could do away with RCD protection but real question is why would you want to? With the old coiled mineral insulated rings spills could cause moisture to enter the element and it would then trip the RCD. But with a ceramic hob water can't reach the element even if it had one and if water gets into the electronics of the induction hob having the RCD trip may save the hob so there seems no reason for not having RCD protection to the hob. My cooker has been RCD protected at 30ma for last 25 years without a problem both cookers had ceramic hobs.

 

[Neilpick]

Thanks for the info. The spare slot on my consumer unit is on the non-RCD side - the RCD side is full. Is it easy to move things around to create a space on the RCD side? (My lack of electrical installation experience showing through now!!!)

Thanks

 

[ericmark]

Depends on CU but the easy way is to use a RCBO which is a RCD and MCB combined. However although same width they are often longer and old CU will often not take the length.

Bus bar kits can allow you to reconfigure the CU but if so old that it will not accept a RCBO then parts may no longer be available.

Today all circuits are normally RCD protected and so today consumer units are designed to take non and all RCBO's, one and a row of RCBO's, two with one or two RCBO's or just two RCD's the more MCB's that are supplied by a RCD the more likely the RCD is to trip when it shouldn't so it's really down to the more you pay the less likely to trip when it shouldn't.

There are exceptions and one is allowed sockets marked as for nothing else to supply things like the freezer without RCD protection.

The RCD can be damaged by strain on the leads so after fitting a RCD it has to be tested. We use a special meter which tests it does not trip on pos and neg part of cycle then it does trip on pos and neg part of cycle then it trips within 40ms again on pos and neg part of the cycle. There is a test button on the RCD but this only tests if stuck. So fitting a RCD is really not a DIY job as it would cost more than the price of fitting one to hire the tester.