Power connection of 7KW induction hob in UK

[Scott]

Can someone advise that the normal method to connect such induction hob to
the power supply in the kitchen of UK houses. Does it use a cable with both
ends of fixed connections to the junction boxes of hob and power outlet by
no means of plug and socket? Does the power cable come with the hob
normally or provide by the qualified installer?

Thanks,

Scott

 

[Andrew Gabriel]

Can someone advise that the normal method to connect such induction hob to
the power supply in the kitchen of UK houses. Does it use a cable with both
ends of fixed connections to the junction boxes of hob and power outlet by
no means of plug and socket? Does the power cable come with the hob
normally or provide by the qualified installer?

I waited to see if anyone else answered, as I haven't actually seen
a 7kW induction hob. I assume this is a fitted item (not portable).

Assuming it's connected in the the same way as a conventional electric
hob of that sort of power rating, it won't come with any lead -- the
installer would have to provide one, and it would then be permanently
wired in at both ends. The circuit would be fused at somewhere between
30A and 45A, and the cable conductor size could be between 4mm^2 and
10mm^2, partly depending on the circuit fuse rating, and partly on what
cable the installer has handy.

 

[Scott]

I waited to see if anyone else answered, as I haven't actually seen
a 7kW induction hob. I assume this is a fitted item (not portable).

Assuming it's connected in the the same way as a conventional electric
hob of that sort of power rating, it won't come with any lead -- the
installer would have to provide one, and it would then be permanently
wired in at both ends. The circuit would be fused at somewhere between
30A and 45A, and the cable conductor size could be between 4mm^2 and
10mm^2, partly depending on the circuit fuse rating, and partly on what
cable the installer has handy.

Andrew,

Many thanks for your useful information. This is not a portable one and
fitted one with 4 zones. Is there any standard reference for the fitting
dimensions of this type of product?

Scott

 

[Andrew Gabriel]

Andrew,

Many thanks for your useful information. This is not a portable one and
fitted one with 4 zones. Is there any standard reference for the fitting
dimensions of this type of product?

I don't know -- you could download the instructions for some inset
hobs and see. The standard kitchen unit size in UK (and all EU I think)
is exactly 600mm wide by approx 600mm deep, so you'd need to fit well
within that if you want to fit on a standard unit. Gas hobs have strict
requirements on side clearance from overhead cupboards manufacturer,
which usually means there's very little scope for any movement in the
positioning to fit under a 600mm wide extractor unit flanked by wall
cupboards. There are no such overall rules for electric hobs, although
the manufacturer can specify their own.

Common worktop thicknesses are 32mm and 40mm thick, and most hobs are
designed to fit within the worktop depth so they don't hang below the
underside of the worktop. Doesn't seem that important to me, but it
probably makes it easier to fit in some cases.

In a tiny kitchen, appliances to fit in 500mm wide units are sometimes
used, but there isn't a big choice of such compact appliances.

 

[Scott]

I don't know -- you could download the instructions for some inset
hobs and see. The standard kitchen unit size in UK (and all EU I think)
is exactly 600mm wide by approx 600mm deep, so you'd need to fit well
within that if you want to fit on a standard unit. Gas hobs have strict
requirements on side clearance from overhead cupboards manufacturer,
which usually means there's very little scope for any movement in the
positioning to fit under a 600mm wide extractor unit flanked by wall
cupboards. There are no such overall rules for electric hobs, although
the manufacturer can specify their own.

Common worktop thicknesses are 32mm and 40mm thick, and most hobs are
designed to fit within the worktop depth so they don't hang below the
underside of the worktop. Doesn't seem that important to me, but it
probably makes it easier to fit in some cases.

In a tiny kitchen, appliances to fit in 500mm wide units are sometimes
used, but there isn't a big choice of such compact appliances.

Andrew,

Thanks for your useful info. Have a nice weekend!

Scott

 

[Andrew Gabriel]

With the new induction hobs the power used does get quite high.
Also with boost feature there is little or no diversity so 7Kw does
need a full 32A supply it can't also feed the oven.
This would likely on a new build be 6mm² cable or over maybe Ali-tube
rather than twin and earth so it does not need a RCD and as standard
protected by a B32 MCB (Miniature circuit breaker) However with an
induction hob this may need changing for a fuse specially designed for
semi-conductors and one must carefully read the manufactures
instructions.

[In UK] the circuit fuse/breaker is only to protect the circuit
wiring, not the appliance. If the appliance requires specific fusing
in order to remain safe which isn't covered by any likely circuit
fuse in use (a likely max value would be 45A in this case), such
protection must be included in the appliance by the manufacturer,
and they mustn't rely on the circuit protection to do this.

Changing the supply protective device requires one to carefully
measure earth loop impedance and prospective short circuit current
(ELI + PSC) and this requires the use of expensive meters. Also the
RCD if fitted may need testing again needing an expensive meter and
all the results will need forwarding to local authority building
control (LABC) in England or Wales if this is done by DIY you have to
pay £100+ fee and inform them before you start under Part P.
As a result under most circumstances it is not worth doing DIY and it
is both easier and cheaper to use a registered electrician.

Since the supply protective device should already be correct to
protect the circuit wiring which is already installed, there is
no reason to change it. (You might choose to double check that
the protective device is appropriate for the circuit though.)