Wiring for 2x 3.6kw ovens, & “Currys Team (don’t) Know How”
Discussion
jackofall84 said:
OP - As per usual on these questions I've seen a lot of nonsense replies - I'm not sure why people bother posting an answer when they don't have the faintest idea...anyway, I'd break it down like this:
Firstly work out the max current draw of the 2 ovens...Power = Volts x Amps so (2*3600)/230 = 31.3A, so if you've got both ovens on at the same time warming up from cold its asking a lot from your 32 Amp breaker, get a sparky in to swap that breaker for a 40A or 45A breaker or swap it yourself if you feel confident, will take 5 - 10 minutes to fit and the breaker will cost less than £5.
Secondly, according to the IEE 4E1A table the worst case installed scenario for 6mm cable is 45 Amps. So all wiring and switches can remain as they are perfectly safely.
Simple
If anyone’s tempted to DIY a breaker change, go to bed and reconsider when sober.Firstly work out the max current draw of the 2 ovens...Power = Volts x Amps so (2*3600)/230 = 31.3A, so if you've got both ovens on at the same time warming up from cold its asking a lot from your 32 Amp breaker, get a sparky in to swap that breaker for a 40A or 45A breaker or swap it yourself if you feel confident, will take 5 - 10 minutes to fit and the breaker will cost less than £5.
Secondly, according to the IEE 4E1A table the worst case installed scenario for 6mm cable is 45 Amps. So all wiring and switches can remain as they are perfectly safely.
Simple
To the OP: as often needs to be the case with a discussion on the Internet I would recommend you take all the correct bits from our individual postings and discard the rest. Then invite us all round for a roast once you're up and running. I'll bring a takeaway pizza menu with me, just in case. 
jackofall84 said:
Apologies, this is the right table
Still a pointless post......OP says in his original post that the manufacturers state a dedicated 16A supply for each oven
Therefore why anyone feels the need to validate their maths is kind of interesting & then why you'd conclude that they'd need more than 16A, so just change the MCB yourself is, quite frankly, mind blowing.
Similarly, I guess it's possible that after clearly specifying 16A, that they would over spec the cable & add additional cost to their product - you never know
jackofall84 said:
OP - As per usual on these questions I've seen a lot of nonsense replies - I'm not sure why people bother posting an answer when they don't have the faintest idea...anyway, I'd break it down like this:
Firstly work out the max current draw of the 2 ovens...Power = Volts x Amps so (2*3600)/230 = 31.3A, so if you've got both ovens on at the same time warming up from cold its asking a lot from your 32 Amp breaker, get a sparky in to swap that breaker for a 40A or 45A breaker or swap it yourself if you feel confident, will take 5 - 10 minutes to fit and the breaker will cost less than £5.
Secondly, according to the IEE 4E1A table the worst case installed scenario for 6mm cable is 45 Amps. So all wiring and switches can remain as they are perfectly safely.
Simple
jesus H. Firstly work out the max current draw of the 2 ovens...Power = Volts x Amps so (2*3600)/230 = 31.3A, so if you've got both ovens on at the same time warming up from cold its asking a lot from your 32 Amp breaker, get a sparky in to swap that breaker for a 40A or 45A breaker or swap it yourself if you feel confident, will take 5 - 10 minutes to fit and the breaker will cost less than £5.
Secondly, according to the IEE 4E1A table the worst case installed scenario for 6mm cable is 45 Amps. So all wiring and switches can remain as they are perfectly safely.
Simple
What is it about electrical advice that brings out so many walts though?
BaldOldMan said:
Still a pointless post......
OP says in his original post that the manufacturers state a dedicated 16A supply for each oven
Therefore why anyone feels the need to validate their maths is kind of interesting & then why you'd conclude that they'd need more than 16A, so just change the MCB yourself is, quite frankly, mind blowing.
Similarly, I guess it's possible that after clearly specifying 16A, that they would over spec the cable & add additional cost to their product - you never know
That's 16A/oven, not for both ovens, so minimum of 32A is required to run both at full throttle. As smiler said, you'll probably get away with running both at 32A as it's extremely unlikely it'll pull that much and as it was pointed out to me the load carrying capacity of 6mm cable is 32A not 45A so best leaving the breaker as is at 32A to protect the existing cable more than anything.OP says in his original post that the manufacturers state a dedicated 16A supply for each oven
Therefore why anyone feels the need to validate their maths is kind of interesting & then why you'd conclude that they'd need more than 16A, so just change the MCB yourself is, quite frankly, mind blowing.
Similarly, I guess it's possible that after clearly specifying 16A, that they would over spec the cable & add additional cost to their product - you never know
changing an MCB yourself is not mind blowing...https://www.youtube.com/watch?v=n33S60qmU5w - if you think that looks difficult I'd hate to think how you would have managed 15 - 20 years ago when you had to wire a plug on a device.
Oh dear, you still don’t get it.
When you open with this you’d better be right or you’re kind of setting yourself up....
The one thing that absolutely didn’t need touching is that MCB
The mind blowing thing was firstly getting it dangerously wrong and then recommending a DIY swap - not because it’s particularly hard - but it is dangerous which is why you need to be qualified to do it.
When you open with this you’d better be right or you’re kind of setting yourself up....
jackofall84 said:
OP - As per usual on these questions I've seen a lot of nonsense replies - I'm not sure why people bother posting an answer when they don't have the faintest idea....
2 x 16 = 32 The one thing that absolutely didn’t need touching is that MCB
The mind blowing thing was firstly getting it dangerously wrong and then recommending a DIY swap - not because it’s particularly hard - but it is dangerous which is why you need to be qualified to do it.
BaldOldMan said:
The mind blowing thing was firstly getting it dangerously wrong and then recommending a DIY swap - not because it’s particularly hard - but it is dangerous which is why you need to be qualified to do it.
Crazy stupid. All for the sake of £60 odd for an electrician who works out the correct breaker and signs it all off properly. BaldOldMan said:
2 x 16 = 32
The one thing that absolutely didn’t need touching is that MCB
The mind blowing thing was firstly getting it dangerously wrong and then recommending a DIY swap - not because it’s particularly hard - but it is dangerous which is why you need to be qualified to do it.
I always design for worst case, in the UK, AC voltage fluctuates between about 220 - 240 with 230 being the nominal voltage. Taking the lower voltage (220V) and putting it into the Formula P = VI we can see that the current draw for both ovens at full capacity could be 32.7A – so it would trip the 32A breaker. Whilst this is unlikely to happen, I would give myself some head room just to air on the side of caution and have a 40A breaker fitted. Most devices have plenty of head room in the fuse, look at the fuse in the plug on your TV, I ‘ll bet it’s a 13A fuse even though the TV probably only draws about 2A at the most when working correctly, so in actual fact they’ve given head room of 11A!The one thing that absolutely didn’t need touching is that MCB
The mind blowing thing was firstly getting it dangerously wrong and then recommending a DIY swap - not because it’s particularly hard - but it is dangerous which is why you need to be qualified to do it.
Legally and safely speaking you can over size the breaker for the cabling, I suspect even in your own house the 2.5mm cable from your sockets is connected to a 32A breaker though the cable is only rated to carry 17.5A when enclosed in a wall. This is because if there’s a fault (likely to be a short) the current draw will go infinitely high and trip the breaker (or RCD these days) in a fraction of a second, this is nowhere near enough time for the cable to draw enough power to heat itself up to a dangerous level.
Years ago before everyone had breakers in their consumer units, people actually had to pull a fuse out the consumer unit, thread the correct gauge wire through and re-install it….all without calling out an electrician. It’s really not that different from changing a breaker.
jackofall84 said:
I suspect even in your own house the 2.5mm cable from your sockets is connected to a 32A breaker though the cable is only rated to carry 17.5A when enclosed in a wall. This is because if there’s a fault (likely to be a short) the current draw will go infinitely high and trip the breaker (or RCD these days) in a fraction of a second, this is nowhere near enough time for the cable to draw enough power to heat itself up to a dangerous level.
Did you skip out ring and radial in whatever qualification you did? I’m not an electrician but I can spot you are talking absolute bulls
t.Black_S3 said:
Did you skip out ring and radial in whatever qualification you did? I’m not an electrician but I can spot you are talking absolute bullst.
You're always allowed 1 socket on 1 spur (unless you fit an FCU then you can have multiple sockets on 1 spur) that spur will be 1 cable from a socket. It will not have twice the load carrying capacity as the sockets on the ring.t.jackofall84 said:
Years ago before everyone had breakers in their consumer units, people actually had to pull a fuse out the consumer unit, thread the correct gauge wire through and re-install it….all without calling out an electrician. It’s really not that different from changing a breaker.
FFS - take yourself off into a corner and have a serious word with yourself before spouting any more stAn old fuse could be pulled out and re wired - but in doing so was isolated from the live supply. That’s a lot different to taking the cover off a consumer unit. Have a think about it whilst you’re figuring out how a ring works........
Black_S3 said:
You googled that quickly. This is why you don’t watch a youtube video and start fking about with breakers.
I did only find out about the FCU on a spur a few months back, it was really useful though as I have an old coal shed that I wanted to run several sockets in but the only existing socket in there was already on a spur. I just don't think people should be so afraid of their house electrics, it's all about risk management. New consumer units have an isolator switch. You can ensure further the power has been switched off by putting a meter over the breakers to ensure the power is off and safe to work on. king about with breakers.People will soon be buying explosives to light in their back gardens but are terrified to have a go at domestic electrics. Personally I'd feel safer changing a breaker than lighting a firework.
Anyway enough already!
jackofall84 said:
I did only find out about the FCU on a spur a few months back, it was really useful though as I have an old coal shed that I wanted to run several sockets in but the only existing socket in there was already on a spur. I just don't think people should be so afraid of their house electrics, it's all about risk management. New consumer units have an isolator switch. You can ensure further the power has been switched off by putting a meter over the breakers to ensure the power is off and safe to work on.
People will soon be buying explosives to light in their back gardens but are terrified to have a go at domestic electrics. Personally I'd feel safer changing a breaker than lighting a firework.
Anyway enough already!
Congratulations. By the sounds of it you probably have a single 2.5 between the back of a socket and a spur/FCU feeding a whole outbuilding that someone could run likely run electric heaters and god knows what else in.People will soon be buying explosives to light in their back gardens but are terrified to have a go at domestic electrics. Personally I'd feel safer changing a breaker than lighting a firework.
Anyway enough already!
Many CUs don’t have isolators and require the whole house fuse pulling to isolate, which is another level of stupid for a DIYer - even electricians should be calling out the electricity supplier for this.
All so crazy you must be trolling.
Black_S3 said:
jackofall84 said:
I suspect even in your own house the 2.5mm cable from your sockets is connected to a 32A breaker though the cable is only rated to carry 17.5A when enclosed in a wall. This is because if there’s a fault (likely to be a short) the current draw will go infinitely high and trip the breaker (or RCD these days) in a fraction of a second, this is nowhere near enough time for the cable to draw enough power to heat itself up to a dangerous level.
Did you skip out ring and radial in whatever qualification you did? I’m not an electrician but I can spot you are talking absolute bullst.te being spouted by this chap.jackofall84 said:
look at the fuse in the plug on your TV, I‘ll bet it’s a 13A fuse
Assuming it's the factory fitted one and hasn't had the plug replaced by a moron, I'll bet it fking isn't. Jackofall - you need to understand that MCBs and fuses are there primarily to stop cables going on fire. Once you appreciate that you'll realise that everything of yours I've quoted above is wrong, and dangerous.
Also worth reading about fault currents and EFLI etc. If fault currents were infinitely high as you suggest, then none of this would be difficult and hypothetically your main 60/80/100A fuse would be adequate for over current protection of your entire house. Trouble is, they ain't.
A minor point given the other stupidity surrounding it, but also be aware that RCDs don't have overcurrent protection, in my experience at least.
jackofall84 said:
I always design for worst case, in the UK, AC voltage fluctuates between about 220 - 240 with 230 being the nominal voltage. Taking the lower voltage (220V) and putting it into the Formula P = VI we can see that the current draw for both ovens at full capacity could be 32.7A – so it would trip the 32A breaker. Whilst this is unlikely to happen, I would give myself some head room just to air on the side of caution and have a 40A breaker fitted. Most devices have plenty of head room in the fuse, look at the fuse in the plug on your TV, I ‘ll bet it’s a 13A fuse even though the TV probably only draws about 2A at the most when working correctly, so in actual fact they’ve given head room of 11A!
Legally and safely speaking you can over size the breaker for the cabling, I suspect even in your own house the 2.5mm cable from your sockets is connected to a 32A breaker though the cable is only rated to carry 17.5A when enclosed in a wall. This is because if there’s a fault (likely to be a short) the current draw will go infinitely high and trip the breaker (or RCD these days) in a fraction of a second, this is nowhere near enough time for the cable to draw enough power to heat itself up to a dangerous level.
Years ago before everyone had breakers in their consumer units, people actually had to pull a fuse out the consumer unit, thread the correct gauge wire through and re-install it….all without calling out an electrician. It’s really not that different from changing a breaker.
Please, please tell us you're not a qualified electrician who does this & gets paid for it.Legally and safely speaking you can over size the breaker for the cabling, I suspect even in your own house the 2.5mm cable from your sockets is connected to a 32A breaker though the cable is only rated to carry 17.5A when enclosed in a wall. This is because if there’s a fault (likely to be a short) the current draw will go infinitely high and trip the breaker (or RCD these days) in a fraction of a second, this is nowhere near enough time for the cable to draw enough power to heat itself up to a dangerous level.
Years ago before everyone had breakers in their consumer units, people actually had to pull a fuse out the consumer unit, thread the correct gauge wire through and re-install it….all without calling out an electrician. It’s really not that different from changing a breaker.
Why would you think an oven is a constant power device? It's almost certainly not - it's a constant resistance device (within the temperature/resistance characteristics of the elements). The current draw at 220V is lower than at 240V & given we don't know the nominal voltage the OP's oven are rated at we can't speculate on the current draw at 220V or 240V.
Your view that the current is greatest when the voltage is lowest is so wrong it brings into question everything you say. Please confirm that you're not a qualified electrician?
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