JackSmith

Hi, I recently completed an apprenticeship and I am going to be wiring in a new cooker for a friend at their house, they've never had an electrical cooker before. I worked out the load is 9.25 Kw , which means a new fuse way / cooker switch / 10 mm2 cable, right? bu in the manual of the cooker it says the supply cable needed is only 2.5mm2, so does this mean there will be a step-up transformer inside the cooker, I am going to just spur from a local socket into a fuse spur and then into the cooker switch, but as the info i have must be wrong about the current it is pulling, as the manual says only 2.5mm2 cable is needed, how can i work out which size fuse i should put in the spur? and is this right??
any help is much appreciated,
Jack

Nathanl

NO don't spur off the ring for installing a cooker

The load is what you need to think about here. Firstly the cooker needs to be on a seperate ciruit for two reasons 1, Saftey, and 2 cable size demand and protection. When installing a circuit refer to the nice big red or blue book you should have that will have the tables to help you ( regs book) whilst the instuctions may say 2.5mm it may only be a small cooker your installing and not very powerfull without full information i don't know.

Spuring off the ring offers little protection from anything as your only real protection is a 13amp spur?

So quick recap new circuit from board possible 45amp maybe 32 check first..
then down to cooker isolater without socket onit as they now bad practice and from isolater to cooker

If you want cable sizes please post cooker ratings thanks and good luck

william1978

I can't help you with your electrical question,but what is a cooker?

Trimix-leccy

Cooker...big square thing, sits in kitchen. Gets hot and you put food in it [or on it] to cook it, before eating / or / throwing away as it is burnt to a crisp.

USA = Stove / range methinks

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TRIMIX...Deep down you know you want it! Trimix-leccy; pulling the envelope---not pushing it

william1978

Gotcha.

Trimix-leccy

Two Nations seperated by a common language

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TRIMIX...Deep down you know you want it! Trimix-leccy; pulling the envelope---not pushing it

frank

I'm back. Anyone missed me. Nope. Ah well.


Once in New Jersey and had to fill in a form at a shop. Asked the chap over the counter if he had a BIRO! Blank look and starry expression. I think he thought I was mad and had just made up a new word. In the end we figured out that a pencil would do.

Frank

Trimix-leccy

Frank? Frank who?

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InPhase277

I too can't help with the electric install question, but I can help with some basic theory, my fair apprentice. Apparently you are under the impression that because two different cable sizes are in question, there may be a transformer involved. And therein is the flaw. 9.25 kW is 9.25 kW no matter what. It doesn't matter how many transformers it goes through. Amps or volts may change, but the kW remains the same.

Docara

Hi JackSmith

You should not be installing/altering anything in a 'special location' unless you are Part 'P' certified (it's against the law!!!!)

As the manual states 2.5mm2 cable therfore I'm guessing you have a basic electric worktop hob (no grill or oven), these hobs usually comes with a 13A plug (AND FUSE) - now think about it (I'll Wait!!!!)

A fused spur is usually good practive for a piece of fixed equipment but not necessarily in this case.

Now the answer -

With respect to your current calculation remember diversity?

As the hob comes with it's own plug and fuse (probably 13A) - it's up to you what connection arrangement you use - locally switched (normal) socket or an unswitched socket with a DB switch above the worktop (like washing machines etc), alternatively cut the plug off and connect it to a switched fused spur on the kitchen ring in place of the afore mentioned socket.
Remember fuses protect cable NOT people and you need to protect the fixed wiring locally when connecting equipment to it. Think about it - every single piece of equipment sold in the UK has a fuse in the plug or it connects to a fused spur outlet, an eight way extension is still limited to a maximum of 13A by a fuse in the plug (5A round lighting plug not included). The majority of the world only rely on the breaker in the DB for overload protection we have multiple layers of protection starting with the fuse in the plug (3A, 5A, 13A), the DB cutout devices (various values upto 45A and ending with the main 100A cutout fuse installed in the incomer by the electriciay company (before the meter).

2.5mm2 cable is good for approximately 21-24A (48A ish max for the ring). Your ring sockets will have protection at the Distribution Board (DB) to 32A so the ring cable will never be overloaded. The 2.5mm2 cable from the socket/fused spur to the hob will never be overloaded as it is protected locally by the 13A plug/fuse.

Bear in mind the 17th edition regs concerning fixed equipment, RCD and labelling!

As a rule of thumb if a cooker/hob comes with it's own cable from the manufacturer it will probably be OK for a standard 13A connection. If there is NO cable then it will probably need 10mm2 installed to a DB switch on it's own dedicated 45A radial from the DB.

Lastly, not meaning to be nasty but with all due respect - you have asked a very basic question I have to wonder what the rest of you 'apprenticeship' has covered (not)

Regards
Doc

LawnGuyLandSparky

All I can say is, what the heck kind of an apprentice "completes" an apprenticeship and doesn't know who to properly connect a residential stove?

forqnc

He may have served an Industrial Apprenticeship, which would mean he probably is not familiar with housing codes/regulations.

Trimix-leccy

I have NO idea how the UK apprenticeship schemes operate nowadays. My friends son is in his 4th year and I would not trust him to knock a hole in a wall

When I 'served my time' [apprenticeship] I did it with my Father's company [shop?]. It took over 5 years and covered nearly everything He started the 'shop' 63 years ago with his Father. I took it over a few years ago.

My father passed away the day before fathers day [10 days ago]. The funeral is on wednesday and I am expecting a good turnout from all the lads that served their time with him over the years. I can think of 50 or so, I was the last one.

R.I.P Dad....you made me what I am today

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TRIMIX...Deep down you know you want it! Trimix-leccy; pulling the envelope---not pushing it

sparkie

hmmmmmmmmmmm no comment other than- get someone who knows what they are doing to fit it.

As said before should be part P registered.
I would recommend the electricians guide to building control
(green book 17th edition)

oldschool

whatever you do DONT spur off the ring
i dont know what that is, but it sounds like something a hack would do

lectro88

I just finished NASA classes too. When the white tiles fly off during re-entry thats bad right ? finished apprenticeship my ass.
Slept and dreamed about finishing apprenticeship class !

JvH87

9.25 kW = 9250 W

9250/230 = 40.2A

6mm2 can handle up to 40-50A. 6mm2 is sufficient