Induction hobs on rcbos

[Welchyboy1]

Hi there

customer got intemittant tripping of rcd on new induction hob , got service engineer out under warranty

got told by a john lewis engineer that induction hobs need to only be wired on their own rcd/rcbo and not with other circuits like on a split load board

'All induction hobs need to be like this and if you was a qualified electrician you would know this as its in the regs' couldnt tell me exactly what he referring too

i went through the manuf instructs and it says nothing about this at all

i said surely if it was a special requirement for the appliance it should say so in the MInstructions

have i missed something, as he has said he will now be issuing the customer an invoice for an invalid warranty call out

is this standard knowledge amoungst you all?

 

[Dave OCD]

Never heard of that and it sounds suspiciously like :****: to me.

 

[telectrix]

total bull ----. if the hob has a leakage current > 5mA then it's faulty.

 

[Adam W]

I would have said it depends on the size of the hob - you can get single ring induction hobs with a 13A plug on them, which you can't expect a dedicated rcd for.
As for the regs I've heard of provision being made for appliances with high earth leakage current, but you'd expect the manufacturer's data to tell you their appliance has a high leakage current.

I would be inclined to take anything a John Lewis employee says with a pinch of salt - have a look at what reviewers on trustpilot have to say about the service at JL.

 

[Leesparkykent]

I've heard they can be leaky. As its happening intermittently then I would be looking at accumulative earth leakage on that RCD. Ramp test the RCD with loads connected/on and again with loads disconnected the difference between will roughly be the earth leakage. Might be an option to move the hob on to the other side of the board if you have that option. Failing that I may have to go on its own RCBO.

 

[Octopus]

Can you download the installation instructions to see what they say?

Unless its over 2kw a plug is OK - that said its always better to put an induction hob on its own circuit where possible...

 

[davesparks]

If their appliance is leaking that much by design then it almost certainly doesn't meet the requirements for appliances

I really hope I get to meet one of these 'service technicians' one day with their 'it's in the regs' BS

I'd be insisting he point out the exact regulation in the book and informing him that I consider his suggestion of me not being a professional as slander and explain that I'll be seeing him in court

 

[daveb]

If the hob is on its own circuit and not incorporating a socket on the switch then surely the requirement for RCD can be omitted?

 

[Darkwood]

If the hob is on its own circuit and not incorporating a socket on the switch then surely the requirement for RCD can be omitted?

Installation methods and manufacturers requirements are other possible reasons for needing an RCD, not just because its a socket outlet.

 

[telectrix]

If the hob is on its own circuit and not incorporating a socket on the switch then surely the requirement for RCD can be omitted?

all depending on the reference method of the cable installation, of course. ( 522.6.101 ).

 

[davesparks]

If the hob is on its own circuit and not incorporating a socket on the switch then surely the requirement for RCD can be omitted?

Pretty unlikely to be able to omit RCD protection in a domestic installation

 

[daveb]

It can be omitted if it's an existing circuit. You don't need to RCD protect for a change out

 

[Darkwood]

If their appliance is leaking that much by design then it almost certainly doesn't meet the requirements for appliances

I really hope I get to meet one of these 'service technicians' one day with their 'it's in the regs' BS

I'd be insisting he point out the exact regulation in the book and informing him that I consider his suggestion of me not being a professional as slander and explain that I'll be seeing him in court

A good point you make, I would be straight onto JL complaints and inform them of the slanderous comments and that legal action is been considered ... that will crap the hell out of them , I would also ask to see a diploma of Engineering from the clearly underknowledged 'Engineer' they sent out, using the term Engineer and then sending out someone less qualified would be a matter for trading standards IMHO, we all know none of them are and at best maybe sparkies, they cannot even be classed as inhouse trained in specialised products as JL is just an end retailer of many electrical goods from different manufacturers.

 

[Octopus]

I've had a BG engineer trying to tell one of my customers that RCD's are too sensitive for boilers....... what he was trying to say is that the old boiler had significant earth leakage - but HE didn't have a clamp meter, nor an MFT, so quite how he could make such claims is beyond me.

 

[sparky1508]

It can be omitted if it's an existing circuit. You don't need to RCD protect for a change out

I expect even an existing circuit would be buried in the wall less than 50mm and if it's not mechanically protected it needs an RCD. But the other thought if its constantly tripping the RCD then even in its own RCBO it will be tripping.

Sent from my SM-G361F using Tapatalk

 

[davesparks]

It can be omitted if it's an existing circuit. You don't need to RCD protect for a change out

You can't just go and remove RCD protection because the circuit is pre-existing!

 

[daveb]

You can't just go and remove RCD protection because the circuit is pre-existing!

Was assuming that the protection was fitted at the same time as the new hob actually

 

[Welchyboy1]

If the hob is on its own circuit and not incorporating a socket on the switch then surely the requirement for RCD can be omitted?

New circuit/chased in wall, so i cant omit the rcd unfortunately

it is a large hob, 800mm accross, 25a supply req. so required radial

 

[Welchyboy1]

It has solved the problem, but as i said to the customer, the hob must have an abnormally high earth leakage

i would not have though that by intentional design?

Certainly without some warning in the instructions

 

[Midwest]

New circuit/chased in wall, so i cant omit the rcd unfortunately

it is a large hob, 800mm accross, 25a supply req. so required radial

Correct me if I'm wrong, and I'm often am, but cannot your apply diversity to this appliance when calculating the load.
I had a similar issue with an electric Aga range oven with an induction hob (15kw total load). It was being reinstated into a kitchen refurbishment. The original connection (old kitchen) had been done by Aga engineers, and had been happily running on a 32amp supply. Checking with Aga about the total load for their appliance, they recommended 45amp supply. I mentioned diversity, which was met with silence. So hedging my bets, I installed 10mm cable (only 3m from CU) with 32amp breaker, and have had no probs with it (touch wood).