3KW cooker on dedicated 45 amp circuit.

[keenbutconfused]

I have an electric oven that runs on its own circuit. My hob is gas.

The oven is rated at 2800 watts.

The circuit is protected by one 45amp wired fuse in the consumer unit.

Is it a problem that the fuse would appear to be too high for the oven?

Previous posts suggest an oven with this rating would normally be put on a 30 amp circuit.

My understanding and remember I have chosen my name for a very good reason is that the fuses in plugs and consumer units are there for two reasons.

Firstly, they are there so that if a current is drawn that would overload the cable used it would trip, hence ensuring that the dangers of cables overheating and causing fires is limited.

The cable used is 6mm t&E so with just this oven on there appears no danger of overloading happining. SO from this point of view I am assuming it is safe.

However, the second reason for fuses is to trip in the case of a short circuit, hence limiting the risk of electric shock.

Consequently, with only the protection of the 45 amp fuse is it possible that a fault could occur that would not cut actually trip the fuse?

As ever thanks for your help.

 

[andy]

you have a choice. either change the fuse to a 16A or change the cooker outlet for a FCU, fused at 13A

 

[plugwash]

that oven needs suitable overcurrent protection either through a 13A fused plug/socket pair a 13A FCU a 16A mcb in the CU or a 15A fuse in the CU.

whilst you could keep the 45A fuse in the CU provided other overcurrent protection is in place i always think its bad practice to use a higher rating that nessacery.

can you provide some more details.
1: did the oven come with flex and/or a plug and if so what size?
2: what is there between the oven and the consumer unit? a cooker control unit (big switch possiblly with socket)? a cooker connection box (box with 3 large terminals used to connect cable from cooker to cable in the wall) a fused connection unit? anything else? (provide photos if you can't identify stuff)
3: what type of consumer unit do you have?

 

[keenbutconfused]

No other overcurrent protectoin between oven and consumer unit.

It is connected to the cable coming from the consumer unit via a junction box.

The consumer unit is one with fusse that require fuse wire to be put in them. They are placed in removable plugs. The oven one is on the far right of the consumer unit in a green plug. This one looks different to the other ones.

My assumption is that old electric ovens were not as efficient as new ones and consumed more power. Hence the 45a circuit was put in to cope with an old oven. When they installed the new oven about 5 years ago they just put the new oven on the same circuit. Being my house they of course bodged it and didn't bother with a cooker switch.

Does a cooker switch have a fuse in it?

From my description of the consumer unit does anybody have any sample pictures of consumer units that might match. I have no way of taking a photo of it myself.

 

[andy]

anybody have any sample pictures of consumer units that might match. I have no way of taking a photo of it myself.

unlikely. do you know how many differnt variations of CU there are?

what you need to do is replce the 45A with a lower rating. and the 45A is bigger because it carries more current, aswell as the fact some cookers have hobs which need more power than a fan assisted over. its not because newer 1 dont need 45A

 

[AdamW]

A 45A circuit is almost certainly intended to allow use of an electric hob... Remember that because a hob is just radiating heat left right and centre it is not thermally efficient, but an oven has a door and insulation all round it. A 10kW oven would allow serious temperatures inside!

To answer one of your questions, a cooker switch has no fuse in it.

 

[plugwash]

No other overcurrent protectoin between oven and consumer unit.

It is connected to the cable coming from the consumer unit via a junction box.

The consumer unit is one with fusse that require fuse wire to be put in them. They are placed in removable plugs. The oven one is on the far right of the consumer unit in a green plug. This one looks different to the other ones.

My assumption is that old electric ovens were not as efficient as new ones and consumed more power. Hence the 45a circuit was put in to cope with an old oven. When they installed the new oven about 5 years ago they just put the new oven on the same circuit. Being my house they of course bodged it and didn't bother with a cooker switch.

Does a cooker switch have a fuse in it?

From my description of the consumer unit does anybody have any sample pictures of consumer units that might match. I have no way of taking a photo of it myself.

most likely a wylex standard

they can be fitted with rewirables cartridges and mcbs i suspect the reason the 45A looks different is because its cartrige rather than rewirable
http://www.tlc-direct.co.uk/Main_Index/Consumer_Units_Index/Wylex_Standard_Range/index.html
http://www.tlc-direct.co.uk/Main_Index/Consumer_Units_Index/Wylex_Standard_Carriers/index.html
http://www.tlc-direct.co.uk/Main_Index/Consumer_Units_Index/Wylex_Rewireable/index.html

if this is the case i suggest the easiest soloution to your situation is to replace the 45A fuse with a 16A mcb

 

[ban-all-sheds]

Or 15A rewireable

 

[keenbutconfused]

I have rewireables as in the pictures on the left and one standard 45amp carrier on the right seperate from the others.

Is that because you can't get 45amp fuse wire?

 

[plugwash]

i suspect you can get 45A but wylex don't do a carrier for it.

i suggest you get a 16A mcb of the type i listed and fit that to the cuircuit. when you fit it you should change the base to the one supplied with the mcb (the bases are held in by small screws).

 

[ban-all-sheds]

I suggest you spend as little as possible on the existing CU, and instead put the money towards replacing it with a modern one with MCBs and RCD/RCBO protection....

 

[Qedelec]

Keen, if I umderstand you correctly, there is no cooker switch.
It is a condition of BS7671 that a means of isolation is provided for all current using equipment, so you will need to provide a switch. A fuse is not regarded as an adequate means of isolation

 

[keenbutconfused]

Does replacing the 45 amp fuse with an mcb require any actual rewiring at the consumer unit or is it a case of unplugging the existing fues unscrewing the base and putting in the new one.

What I am trying to ask is do I need to connect the cable to the new mcb itself or is that done ssomewhere else in the cu.

 

[plugwash]

no wiring should be needed with that style of CU just unplug the fuse unscrew the base and fit the new base and mcb.