Electric Hob and Oven connection, one supply.

[robert 1950]

Installation of a cooker in a renovated property, electric oven and a separate induction hob. The hob was to be gas - now with the induction hob, can it be fed from the oven radial via a dual wall outlet? The radial from the Consumer unit is 10mm T + E. The local isolation requirement can be met by the 45a switch cutting off oven and hob together. Switch, outlet and oven/ hob are within a metre or so of each other. Advice please guys.

 

[davesparks]

What local isolation requirment?

If the combined load of the appliances, after diversity, is within the capacity of the circuit then yes they can be connected to the same circuit.

 

[Dustydazzler]

Yes you ca; have 1 switch that isolates both the oven & hob

Thou some manufactures instructions ‘might’ ask for 16/20a circuit protection

 

[Wilko]

Hi - dual wall outlet should be fine, but as per Dave you need to confirm loading.

 

[robert 1950]

What local isolation requirment?

If the combined load of the appliances, after diversity, is within the capacity of the circuit then yes they can be connected to the same circuit.

I thought there was a requirement for permanently wired in appliances to have local isolation - a plugtop, or a switch near the appliance, and accessible. Otherwise its a hike to the Consumer unit. Theres a switch in place, so all seems OK, no need for running a complete new feed to the Hob from the CU. Thanks for advice.
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Yes you ca; have 1 switch that isolates both the oven & hob

Thou some manufactures instructions ‘might’ ask for 16/20a circuit protection

Hob and Oven arent purchased yet, so will check out the words from the Manufacturer - as they are separate items, most like the Manufacturers will assume they need separate protection, but if installed as a pair, then I would class that as One appliance. Thanks for advice.

 

[Lucien Nunes]

if installed as a pair, then I would class that as One appliance

DD points out a significant snag, if the oven manufacturer specifies protection at a lower rating than is needed to supply them both, for example maximum 20A. A 20A MCB would be inadequate for both oven and hob, while a 32A would leave the oven without the specified protection.

I'm actually interested in what people do in this situation. On Saturday, I watched an oven being delivered and installed by the retailer's installation service. The instructions stipulated 'fuse min 15A max 20A'; the installer connected it to an existing circuit on a B40. I can imagine the retailer limits their responsibility by stating that the appliance will be connected to whatever supply the customer provides and that it is up to the customer to confirm suitability. Personally I don't think it's a great idea to simply ignore the MI's on this point.

 

[telectrix]

MI should "be taken into consideration", not blindly followed. also the appliances are fixed loads insofar as they can short circuit but not overload the cable (with the proviso that the cable is capable of supplying the load).

 

[Lucien Nunes]

I agree that MI's should not be blindly followed but that is really to cover situations where an instruction does not apply, or conflicts with BS7671 or the like. E.g. 'Connect a green #14 ground wire' on a US appliance can be varied to use green/yellow 2.5mm². Not providing OCPD within the maximum specified value because it's inconvenient to do so, I would consider to be ignoring a safety provision without adequate reason.

 

[robert 1950]

DD points out a significant snag, if the oven manufacturer specifies protection at a lower rating than is needed to supply them both, for example maximum 20A. A 20A MCB would be inadequate for both oven and hob, while a 32A would leave the oven without the specified protection.

I'm actually interested in what people do in this situation. On Saturday, I watched an oven being delivered and installed by the retailer's installation service. The instructions stipulated 'fuse min 15A max 20A'; the installer connected it to an existing circuit on a B40. I can imagine the retailer limits their responsibility by stating that the appliance will be connected to whatever supply the customer provides and that it is up to the customer to confirm suitability. Personally I don't think it's a great idea to simply ignore the MI's on this point.

Forgive my ignorance, but if one of the appliances requires a lower rating than the other, and the feed is protected by an MCB to suit the higher requirement, then in the event of a fault wouldnt the RCD protecting the Cooker/ Hob circuit ( and others) trip out first? So the MCB would be for circuit isolation rather than fault protection - or am I talking nonsense?

 

[Lucien Nunes]

An earth-fault will trip the RCD but not a fault L-N.

 

[robert 1950]

An earth-fault will trip the RCD but not a fault L-N.

So the higher rated appliance fed via the dual outlet, DP cooker switch, back to CU with appropriate rated MCB, and the lower rated appliance fed through a separate fuse arrangement, to dual outlet and to CU - access is the issue somewhat, so could the separate fuse arrangement be a (say) 20a MCB mounted in a kitchen cabinet adjacent to oven/ hob outlet? Any thoughts on a standalone MCB housing, do they exist, or an inline fuse of some kind? I want to keep it simple, safe and as little hassle as possible.

 

[Lucien Nunes]

I'm guessing the requirement to fuse down is usually overlooked unless 13A is adequate so it can be done with an FCU. Waiting to hear others' opinions. Never hit the issue myself as I've never done domestics.