Oven 20amp which MCB

[ssl0kxp]

Hi,
I am refitting my kitchen and will add an electric oven (currently Gas)

The specs document states it should be fused at 20amp for which I plan on using the MK Grid 20amp DP switch. I have an 'old' consumer unit using Wylex 'NB' MCB's. As these are hard to find (than NSB's) I want to make sure I get the correct one for the new circuit (I only have a spare 15/6amp...).

What would be the cvorrect size of MCB, 30amp?, or is there another between 15 and 30amp?

Thanks in advance
(by the way I did try the search...)

 

[JohnD]

What is the current loading for your new oven (Amps of kW or watts?) It will be in the brochure and also on a rating plate that will be either inside the door or on the back near the cable entry.

Do you already have a cooker circuit?

 

[slippyr4]

The specs document states it should be fused at 20amp for which I plan on using the MK Grid 20amp DP switch

Two points:-

- don't be confused at the 20amp DP switch - it's not a fuse - the 20 amp means it can safely switch 20 amp loads.

- you said the oven documentation states that the oven should be fused at 20 amps. Thus you should probably fuse the thing at 20 amps.

 

[kai]

Oven = use a B20 breaker, nothing else.

 

[ssl0kxp]

I have not taken delivery, however the document states the following:
Connection Load:2500 Watts
Fuse Rating: 20 amps

So to recap:
MCB should be 20amp

Questions:
Can I use the 20amp DP MK Grid switch or should I go for a 32amp cooker switch?

Should I stick with the (usual) 6mm T&E cable to make the connection to the consumer unit?

Thanks again

 

[JohnD]

...Connection Load:2500 Watts...

If that the correct max load then a 20A MCB is more than adequate. You could actually run it off a 13Amp plug. Your 15A MCB would be adequate.

They have perhaps chosen 20A because it is a common size.

In my view, the nearer the fuse/MCB protection is to the max load of the appliance, the better - because then it will trip quickly in the event of a fault, without needing the fault current to be (as in the case of your 20A MCB) more than double the normal load to have a quick trip.

If you are having a Cooker Circuit installed, it is good sense to have the cable and a cooker switch of normal 45A size (6mm min cable for 32A, maybe even 10mm in case one day you buy a huge electric range cooker) as the upheaval and installation effort will not be much greater and it gives scope for a simple later upgrade.

(I would be worried about trying to terminate 6mm cables in a gridswitch)

 

[slippyr4]

To clarify what JohnD said - your 15A MCB would actually be better, and safer, than using a 20A. So use that.

 

[Spark123]

I have an 'old' consumer unit using Wylex 'NB' MCB's. As these are hard to find (than NSB's).

Try here
http://www.tlc-direct.co.uk/Main_Index/Consumer_Units_Index/Wylex_NN_Range/index.html

 

[JohnD]

To clarify what JohnD said - your 15A MCB would actually be better, and safer, than using a 20A. So use that.

Clear and concise, Slippy.

I must talk less

 

[ssl0kxp]

Thanks again to all for you comments.

As the max connection load is 2500 watts, does that mean the connection cable (consumer unit to oven distance = 4m max) could even be 4mm T&E?

As I plan on installing the circuit myself (get the council to check out the install etc) will it be against regulations/rules to use a 4mm T&E utilising the MK 20amp GRID switch?

Whilst I understand the argument for in the future replacement... I expect this to be the only oven I'll need to install in the next 10 years

Thanks

 

[slippyr4]

As the max connection load is 2500 watts, does that mean the connection cable (consumer unit to oven distance = 4m max) could even be 4mm T&E?

You could even use 1.5mm T+E. But don't, use 2.5mm minimum. The advise for a bigger cable was future proofing. 4mm is larger than you need, and you might as well either a) use the smallest appropriate cable (2.5) or b) put something future proof in (6 or 10). 4mm is a bit useless.

As I plan on installing the circuit myself (get the council to check out the install etc) will it be against regulations/rules to use a 4mm T&E utilising the MK 20amp GRID switch?

No, just fine. So long as the CU fuse is not more than 20A, the grid switch is cool.

 

[kai]

on a 2500 watt load... a 1.5. mm cable will do (current capacity is 16amps in conduit) provided the run is very short, and the Fuse/MCB is 15/16 amps, and EFLI of run OK.

 

[ssl0kxp]

thanks again all for the advice.