CALLING ALL EXPERTS

[sparkattack]

Hi all,
First post here but been a frequent visitor and avid reader of the site.

Just bought an electric double oven to replace my single oven.
Budgets tight and spent more than i wanted to on the cooker so looking to save myself some pennies by installing it myself.

I'm not taking this task lightly or under estimating the job at hand,hence why am here consulting with you guys.

So bit of info for you in regards to the job

House was just built 6 year ago so i'm assuming the electrics are sound

The oven i've bought is the hotpoint hue61 it has a max load of 10.7 kw and hotpoint say 45a required and that's my problem i only have a 40a mcb.

The consumer unit is a wylex the current mcb is a nsb40.

As i understand it wylex don't do a nsb45 0nly a nsb50.

So my question too you guys are should i replace the 40amp with a 50 amp?

Also my current cable i intend to use is two metres long and 6mm is this safe to use? or should i go for 10mm from cooker to hardwiring point behind cooker.

Thanks to all that take the time to read and reply to this post,look forward to reading your replies.

 

[Adam_151]

The oven i've bought is the hotpoint hue61 it has a max load of 10.7 kw

Just looking on the internet, I can't bring up anything for an oven under hue61... it seems to refer to a complete standalone cooker (incorporating ovens and hob), which does seem to tally with the 10.7kw rating (which seemed excessive if the appliance is just a twin oven)... please confirm that it is a standalone cooker you have purchased?

What size is the fixed wiring for the cooker circuit? Its very unlikely to be anything other than 6mm² I'd guess unless someone put an unusual spec in for these builds (very unlikely!)

OSG cooker diversity recommendation is the first 10A, then 40% of the remainder + an extra 5A if socket on cooker switch.

So 10.7kw is 46.52A, first 10A taken leaves 35.52A, 40% of this is 14A, so with the original 10A, thats 24A to allow... 29A if theres a socket. On standard diversity guidelines it'll be fine on a 32A circuit, not sure why hotpoint think you need 45A for it.... thats only needed for double width range cookers, etc

 

[sparkattack]

Thanks for the quick reply adam and thats good news if your calculations are right and i can use the 40a mcb thats already in the consumer unit.

This is the cooker if you click on full specs you'll find the info re max load and amperage

http://www.rangecookers.co.uk/hotpoint-hue61-ultima-60-s-steel-product,2946.aspx

 

[Adam_151]

Its a standard size cooker, your standard cooker circuit will be fine

 

[EFLImpudence]

, then 40% of the remainder + an extra 5A if socket on cooker switch.

Actually 30%

The oven i've bought is the hotpoint hue61 it has a max load of 10.7 kw and hotpoint say 45a required and

Are you sure it said 45A breaker required and not just stating what 10.7kW is in amps.

A manual I found stated 'minimum 32A supply required' which would be usual and what I would suggest.
http://www.hotpoint.co.uk/hotpoint/_pdf/manuals/19508241000_UK.pdf

 

[EFLImpudence]

Just seen your link.

It does say 45A fuse but is from the sales company.

Look on page three of my link to Hotpoint.

 

[PrenticeBoyofDerry]

Just seen your link.

It does say 45A fuse but is from the sales company.

Look on page three of my link to Hotpoint.

Just seen the link to, so as mentioned.
It is permitted in a domestic installation, for a cooker up to 15kW to be protected by a 32A protective device, taking diversity in to consideration.
4.00mm cable can carry a maximum of 37A providing no other factors such as containment, thermal insulation, ambient temperature, grouping factors and voltage drop come in to the design calculation.

 

[sparkattack]

Again thanks for your replies guys.

Read the link from elfimpudence and seems all is good,especially since the hotpoint pdf contains a cooking guide so know more excuses for the missus burning my dinner.

Just read your post prenticeboyofderry so are you reccomending i go with the 45amps?

What are the dangers of hardwiring this cooker with a 40a if it was at full load?

Would it simply trip the mcb or worse burn the house down?

 

[PrenticeBoyofDerry]

sparkattack, sorry I edited my post after seeing link to hotpoint and EFLI post and foolishly deleted the contents of the some of the post
In summary I was stating the values providing no corrective de-rating factors.
That on full load just under 47A amps would be used(rarely/if at all happens)
and 6.00mm T&E will be suitable. You will get away with using either a 40A or 45A MCB/RCBO to protect the cable and achieve somewhere near optimum output power if ever needed.
It will be very unlikely that full load will ever be used, a 40A device should trip on overload. If the cable size is correct and erection methods followed the likelihood of a fire hazard will be down to your missus cooking!

 

[sparkattack]

Brilliant news.

Cheers for taking the time guys.much appreciated.

 

[ban-all-sheds]

Manufacturer's instructions should be followed, but...

In this case it'll be difficult. You can't necessarily replace your B40 with a B50, as the cable may not be rated to carry 50A, and it has to be at least as high as the breaker.

See //www.diynot.com/wiki/electrics:mcbtocable.

But the cooker can't possibly be damaged by being on a 40A breaker instead of a 45, nor are you at all likely to overload it.

 

[EFLImpudence]

.
I thought it had been decided to use a 32A breaker.

 

[sparkattack]

Good to know ban-all-sheds

Not a fan of B&Q i take it

 

[sparkattack]

.
I thought it had been decided to use a 32A breaker.

Bugger i thought it had been decided to use the 40a already in place?

 

[PrenticeBoyofDerry]

As stated in previous posts and also the post I edited and deleted
It is important to follow the manufactures instructions. If they are not followed and a fault, hazard happens regarding this appliance it is likely that the manufacturers will invalidate any warranties and hold you responsible or the electrician doing the install. If worse comes to worse there could be legal issues over it!
But saying that 40A providing the cable is equal to or greater than 6.00mm t&e you would be okay!
It's your choice