Wiring Up Cooker Just Checking Figures

[Darkstalker420]

Hi my mother purchased a Belling cooker and i would like to wire this up for her (she can't realy afford a sparky at the moment). The cooker is rated at 9.8Kw. The cooker box (CCD?) when i opened it said 45A (there is one "plug" socket built into the box).

Now using an online calculator i worked out i would need 6mm twin & earth cable i was going to use about 2m which would be fixed to the wall externally somehow (clips, conduit?).

Do you think this is the correct cable for the job naturally i want to be sure (don't really want to burn my mums house down!!). Will this enable her to operate all the hobs/ovens if needed?

Thanx.

 

[ricicle]

What is the rating of the protective device at the consumer unit ?
Although T+E has been used for years as the connection between cooker and outlet, I do not like it as it is not designed for flexible use. (although you could argue that the cooker will not be in and out regularly)
You would be far better off getting a couple of metres of 6mm² 3 core flex from an electrical wholesalers. It doesn't have to be heat resisting as the cooker will be insulated enough to prevent excess heat externally.

 

[Darkstalker420]

Sorry don't wish sound stupid (i don't know any of the sparky "terminology") how can i find out the rating of the protective device?. Thank you for your help though.

Thanx.

 

[ColJack]

that would be the fuse or breaker in the fuseboard..
it'll be written on it unless it's a rewireable fuse ( the holders of which might be colour coded.. )

 

[Darkstalker420]

Hi looked at the Consumer Unit (the sparky who wired this up needs handwriting lessons lol):

Consumer Unit (Crabtree SB6000)
Main Switch 100A
Cooker 40A (what was printed on the label nothing was "handwriten" like the lights heater etc).

Thanx.

 

[ColJack]

ignore the lable on the box, what does it say actually on the breaker abover the lable?
shouls be something like B32 or B40 etc..

 

[ericmark]

It was called a fuse box but as the fuse was replaced with the miniature circuit breaker (MCB) the name was changed to Consumer Unit which is a type tested distribution unit.

With a fuse it was normal to colour code:-
White = 5A
Blue = 15A
Yellow = 20A
Blue = 30A
However with re-wireable it was not something one could rely on. As we moved to cartridge fuse the diameter limited incorrect use but still possible.

The MCB was an improvement as people were not tempted to fit wrong sizes in the same way and there are a number of types. Originally 1, 2, 3, and 4 but for many years B, C, and D and this type number is placed in front to the thermal trip amps ratting so a B32 with trip with a prolonged load of 32 amp which is what you need to work out cable size.

The B in front of the B32 means it has a magnetic release 5 times size of thermal release so will instant trip at 160A and when we install cable we need to measure the earth loop impedance with a special meter to ensure with a short that current will flow. Ohms law 230/160 = 1.44 ohms maximum earth leakage.

The C is 10x and the D is 20x

With RCD protected circuits this is not so much a problem. However when changing an appliance this should all be tested. At the same time an electrician would look at cable sizes. I have seem 2.5mm feeding a cooker outlet which is well under size but the norm is 6mm however 4mm and 10mm could also be used.

Unlike flex which must never be covered and should be visible throughout it's length. The permanent wiring in a house changes rating according to the environment so the same cable could be rated anything from 23.5A to 47A.

One always hopes that the person before you did it right but it is dangerous to assume. In a new house with no DIY likely no problem but my dad's house had 5 sockets when built, no cooker supply, an immersion heater and lights. Over the years loads have be added and altered and when I last tested I had to remove some damaged cables which had been overloaded.

Without a full test set you are unlikely to locate anything but most obvious fault and even with full test set you will not find them all.

So do a risk assessment! Is it really worth the risk of DIY when you admit you have very limited knowledge so will be unlikely to recognise any existing problems even if you do everything A1.

Most high street outlets do offer an installation and delivery service and to me if one can afford a new cooker the extra to fit it is reasonable.

 

[Darkstalker420]

Popped down to mums:

Nothing above the breaker except Switch Type 1A 40A and the the hand writen "cooker"

Underneath there is A B C D E F

Cooker is A.

Forgive me if i'm missing something but do say so if you need anymore info again thanks for the help



Thanx.

PS Don't worry if i feel that i might be to far over my head a "real" sparky WILL be called as you say it's not worth it just thought i could save the old dear £50+

 

[ricicle]

The 40A means it is 40 Amp. Although 9.8kW is slightly more, this will be fine if you take into account diversity ie not everything being on/calling for heat at once.
So just buy 2m of 6mm² 3 core flex and connect it up, paying close attention to safe isolation and correct termination of wires.
If you are still in any doubt seek competant advice

 

[Darkstalker420]

Found this online:

6mm HO7 Rubber 3 Core Cable

HO7 RN-F
Superb rubber & neoprene sheathed cable, makes this exceptionally tough and flexable in temperatures from -20 to + 85 degrees.
Ideal for professional use.

Max Amps: 55A

Do you think it will work?

 

[ricicle]

Bit OTT but it will definitely do the job

 

[Darkstalker420]

Lol i know but nowt's ott for me old mum the money she would be saving from not having the sparky out can be used to get a better cable (comes to £15 delivered for 2m). And she is forever cleaning behind the cooker so better be safe with an "overkill" cable than risk something snapping.

Have to say this site is great and thank you all for your help .

Thanx.

 

[Darkstalker420]

One more thing how should i best secure the cable to the wall. Can i use conduit cover or should the wire not be covered? is the wire secure in the cooker connection box or is it ok just on the connections alone?

Basically how to "finish" the job off without just leaving a wire carrying lots of electricity dangling out of the box only held on by the end connections! lol .

Thanx.

 

[RF Lighting]

If you've got a proper cooker connection point behind the cooker, which it sounds like you have, when you remove the cover you will see the three connections in a row, and there should be cable clamp just under them which clamps onto the outer sheath of the cable.