New Oven & Hob wiring
- Thread starter Andr'e
- Start date
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The thing that makes no sense here is that if the hob+oven were combined in a single unit, i.e. a cooker, then the diversity calculation would give a lower current rating, even though both cases are identical from an electrical load standpoint.
Diversity is supposed to be applied bearing in mind how the circuits and appliances are used, not by blind adherence to the formulae. It makes no sense to me at all to treat a separate oven and hob any differently from a free-standing cooker that combines the two, since the two are used in the same way (how many sparks actually USE these appliances in anger, I wonder - I do).
If you treat them this way, then even with the 5A for the socket, the load is 26.4A and your 32A MCB is OK.
I guess there might be some argument for the ability to isolate the two appliances independently, but that is the only reason I can see for separate circuits.
Diversity is supposed to be applied bearing in mind how the circuits and appliances are used, not by blind adherence to the formulae. It makes no sense to me at all to treat a separate oven and hob any differently from a free-standing cooker that combines the two, since the two are used in the same way (how many sparks actually USE these appliances in anger, I wonder - I do).
If you treat them this way, then even with the 5A for the socket, the load is 26.4A and your 32A MCB is OK.
I guess there might be some argument for the ability to isolate the two appliances independently, but that is the only reason I can see for separate circuits.
Just ripping out the old all in one cooker to find it's rated at 8.8kW -11.8kW,now that maximum load is more than the two im gonna intall which is 11kW ...So folks do you recon i'll be fine wiring both into the one power outlet with my 32A breaker?Had aquick peek at the cable in the wall looks like 6mm, Might be best to remove the isolator with the 13A socket & just install a plain isolater to be on the even safer side???Should i go for it or not?
Andr'e
Andr'e
I thought the purpose of these postings was to re-assure the poster that he has not just gone and made an expensive mistake. I think we've now beaten it to death! Yes, he can connect to the exisitng single circuit - he didn't want to unecessarily spoil existing decorations by putting in an additional circuit. The calculations we have volunteered hopefully give the poster (read 'customer') the re-assurance just in case someone comes along and does the 'you didn't wanna do that' number.
Get moving mate, your missus will be wanting to do the turkey on Saturday!
Get moving mate, your missus will be wanting to do the turkey on Saturday!
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ltheb said:
Saturday??
Have I missed something?
davelx said:
There are two reasons for connecting the two appliances seperatly:-
1. Isolation of each seperatly
2. The Flex for any appliance is only rated for the load of that appliance
so for the double oven the flex is only rated at 19A. You can not
connect this cable to a circuit which is protected by a 32A Breaker.
Same for the Hob. So connect the Hob(29A) to the Cooker outlet and
Oven on a 13A Plug.
ltheb said:
Bloody hell I havn't started shopping for the missus yet and I'm working till 4 on Friday
miajanjua said:
Yes, but in this case the OP indicates that there is no flex supplied with the hob or the oven, just a specification of the cable type.
"Both the hob & oven specify lead Type H05 VV-F or higher. "
So he can select a suitably rated flexible cable for each that can be protected by a 32A MCB: http://www.tlc-direct.co.uk/Products/CA4TQ3slash50.html
miajanjua said:
Why i'm i getting no solid advice,i thought you were here it assure me i'm not going to cause damage?
I don't see any problem with not isolating each unit seperatly.The oven & hob have off controls on them,if there's a problem i isolate both.I don't honestly believe that oven is safe fitted to a 13A outlet.Regarding fitting the hob to the outlet with a 29A break is a no as Crabtree don't make a 29A for my consumer unit.The oven i have just taken out has a maximum of 11.8kW which exceeds these two new units together & that's with an isolator with a socket,been working perfectly,so whats the probblem connecting both unit to the outlet with dedicated 6mm from the oven & from the hob,just fitting a plain isolator with no socket to take away another 5Amp???Only problem i see is there's no protection for each unit seperatly to match there maximum current rating ,like i say i don't think the oven is safe in a 13A socket!
New idea hows about one of those minature consumer units directly from the oven & hob with dedicated circuit breakers before wiring into the power outlet,not exceeding the 32A breaker at the main cu?
Please assure me folks.
"so whats the probblem connecting both unit to the outlet with dedicated 6mm from the oven & from the hob"
That's what I did in my kitchen (some years ago). Since the oven is located directly under the hob in my case, I saw no need for separate isolation, isolating both at once is perfectly adequate IMO.
That's what I did in my kitchen (some years ago). Since the oven is located directly under the hob in my case, I saw no need for separate isolation, isolating both at once is perfectly adequate IMO.
Wow this one is being beaten flatter than a roadkill. I think Pensdown, davelx and i have all said its ok to use the existing circuit. There's no reason why you can't connect both appliances in to the cooker switch. The only problem will be the amount of cable you are trying to accomodate, so, depending on how the previous connection is made to the appliance, either use a suitable junction box or a 'cooker' connection plate under the worktop in a pattres or back-box which will take 2 x 6mm cables (twin & e is ok - sheath the 'earth wire'!) as the final connection to each appliance.
Forget the mini consumer unit thing, it achieves nothing. The 32a breaker protects the entire circuit, the cooker switch merely isolates the appliances.
Forget the mini consumer unit thing, it achieves nothing. The 32a breaker protects the entire circuit, the cooker switch merely isolates the appliances.
A breaker for a circuit is rated for the design current that the Load will draw.
The cable is then chosen that would safely deliver the current which will trip the breaker.
So if the Oven draws a maximum of 19A then the breaker at the CU supplying the Oven must not be 32A but a 20A breaker to protect the load in the event of a fault developing.
If you fit a 32A breaker to a load which before diversity is 19A, then in the case of an overload fault in the load, there is more likelihood of a fire developing as the breaker would not trip until the load has well and truely melted itself and other things around it.
The cable is then chosen that would safely deliver the current which will trip the breaker.
So if the Oven draws a maximum of 19A then the breaker at the CU supplying the Oven must not be 32A but a 20A breaker to protect the load in the event of a fault developing.
If you fit a 32A breaker to a load which before diversity is 19A, then in the case of an overload fault in the load, there is more likelihood of a fire developing as the breaker would not trip until the load has well and truely melted itself and other things around it.
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