Fuse Rating for Oven

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#2076139 20-Aug-2018 12:03

I only ask as a lower rating circuit would be installed for gas ovens with their electrical supply only needed for the electric starter and clock. Fun when you get home owners swapping in an electric oven and they try to use that same circuit ...

What’s the rating of the isolation switch out of interest?

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robfish

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#2076141 20-Aug-2018 12:03

If you are trying to save money (by not getting a Sparky to have a look) then perhaps a photo showing the cable to the range and some 2.5mm (squared) would enable someone to confirm the size.

As already stated - if you do not have the correct protection for the cable you are "playing with fire" (Literally)

Regarding the power through the 20A CB consider this:-

20A x 230V = 4600W

George Forman Grill typically 1120W

A typical electric oven runs on 2,500 to 5,000 watts (depending on the model, age and mode it's in)

Hob elements typically 1000W to 1200W

I'll let you do the maths.

Rob

nickb800

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#2076151 20-Aug-2018 12:17

If you pull the oven out and have a look on the back panel, there should be a circuit diagram with ratings. You could post it here, along with the rating of the George Foreman, and we might be able to suggest which combinations you can use to keep it under 20A (e.g. might be small elements, or inner of dual element only at the same time as the grill)

ADKM

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#2076197 20-Aug-2018 13:17

Wasn't sure about adding photos here so put some on dropbox

https://www.dropbox.com/sh/x2b8njlqblox7bu/AAAGpI-jfznwxLfkMIRPWnAqa?dl=0

1) Oven

2) isolation switch and phase wire

3) Connector on wall

4) Circuit on back, unfortunately much of it missing

5) Switchboard

6) Oven inspection label

7) 15A internal fuse. This must be just part of the load.

Yes, I'd like to avoid a sparky unless essential. Will try a new fuse first, same rating.

Zeon

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#2076198 20-Aug-2018 13:17

If the cable goes through the roof cavity or under the house and is accessible you could inspect it to ensure that it is consistently up to the required size. It could just be a smaller breaker was put on the switchboard but if the cable has enough conductor in it for the current you should just be able to change the breaker. It's probably better to get an electrician to confirm.

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robfish

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#2076212 20-Aug-2018 13:29

The cable at the switch looks to me to be at least 4mm which is rated at 32A.

Check that is is the same cable at the switchboard end though before "upgrading" the breaker.

If you have to change the base you should enlist a registered electrician. You can void your insurance if you are found to have illegally performed electrical work even if it does not cause a problem - and believe me, insurance companies will usually look to avoid paying any claim if they can.

Rob

ADKM

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#2076229 20-Aug-2018 13:55

I tend to agree its a proper 32A circuit for the oven, but I'm mindful of the warnings.

Am tempted to try a 25A, if the same gauge at the SB... that may stop the tripping without any stress. How much extra heat would 5A generate esp? From Robs figures 20A is cutting it fine with stove, a couple of top elements and George all on at once.

Would certainly not go changing anything to void insurance.

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nickb800

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#2076267 20-Aug-2018 14:56

What functions are you using at the same time as the George Foreman? Looks like bake would be fine (without bake assist - not familar with that), and although grill would exceed the theoretical max, in practice it shouldn't trip a breaker unless used for a long time (e.g. 30mins of oven grill + george foreman)

robfish

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#2076274 20-Aug-2018 15:07

Time is not a factor when current is the issue (it does not increase unless you turn something else on).

Rob

nickb800

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#2076285 20-Aug-2018 15:19

robfish:

Time is not a factor when current is the issue (it does not increase unless you turn something else on).

No, but it does affect whether the circuit breaker (or fuse) decides to trip - they are designed to trip quickly for big overloads, and slowly for small overloads.

I don't have the numbers at hand, but a typical modern C-curve breaker shouldn't trip on a 10% overload unless it's sustained for at least half an hour

kryptonjohn

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#2076293 20-Aug-2018 15:30

ADKM:

Starting to have a 20A circuit breaker on the oven blow quite often.. especially when a George Foreman cooker is also plugged in (to the oven).

It's an older style F&P ceramic all-in-one.... can I determine the correct fuse rating ? What's the opinion about increasing to 25A (although I don't see

any circuit breakers above 20A on line, so maybe 25a fuse wire would do ?)

If you can find the serial number or model number I can probably look it up.

Ah, see on your image it's an RA610MAWS ... and can't find the service manual. If you call F&P customer care they should be able to tell you...

Aredwood

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#2076371 20-Aug-2018 16:50

robfish:
The cable at the switch looks to me to be at least 4mm which is rated at 32A.

Check that is is the same cable at the switchboard end though before "upgrading" the breaker.

If you have to change the base you should enlist a registered electrician. You can void your insurance if you are found to have illegally performed electrical work even if it does not cause a problem - and believe me, insurance companies will usually look to avoid paying any claim if they can.

The cable rating is affected by how it has been installed. For example, 4mm2 cable completely surrounded by insulation is only rated to a max of 18A. So even a 20A breaker would be cutting things very fine. As it could take as much as an hour for a 20A breaker to trip at say 25A.

Can't you just plug the GF grill into a different power point?

Other factors are voltage drop on the cable. And capacity of the mains cable coming into your house. There are houses out there with mains cables that are rated to only 32A.

It might also have originally be wired as 2 phase. In which case 20A per phase would be plenty. And maybe a DIYer has replaced the oven. And wired it as single phase. As multi phase power to them would be the equivalent of black magic.

Just get an electrician to come and check it all.

gregmcc

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#2076384 20-Aug-2018 17:29

robfish:

The cable at the switch looks to me to be at least 4mm which is rated at 32A.

Check that is is the same cable at the switchboard end though before "upgrading" the breaker.

If you have to change the base you should enlist a registered electrician. You can void your insurance if you are found to have illegally performed electrical work even if it does not cause a problem - and believe me, insurance companies will usually look to avoid paying any claim if they can.

Cable rating doesn't work quite like that, other factors to consider, such as length, and how it is run (such as through insulation in the ceiling).

Myself looking at it, it looks like 6mm, but photo's can be deceptive, without knowing the other above factors I would not be making a call on what size circuit breaker to replace it with

ADKM

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#2076391 20-Aug-2018 17:57

> Can't you just plug the GF grill into a different power point?

Could do, with an extension cord. But the whole point was to stop it tripping out, which it shouldn't do. (It isn't 2 phase nor is that wired in here.)

Someone said to ring F&P so I did. The girl there wasn't very convincing and said the current rating was 52A. I don't think that helps.

If I can get a holder, I'll try some 20A fuse wire and see what happens. That saves $30 or so on a circuit breaker that may be no different to what's here now.

robfish

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#2076392 20-Aug-2018 18:11

I am a sparky by trade (but no longer work as one) but if my memory serves me correctly 2.5mm squared has a rating of up to 27A with CCP (close current protection) but less with coarse current protection (rewireable fuses) and 4mm is 32A (or maybe more?)

Rob

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