Why do people uprate cable when it's not required?

[philectrical]

Just sat looking at my old cooker that's sat in my kitchen with a piece of 6mm2 hanging out of it.

Its info plate in the door says it pulls a max of 5.3kw, which using P/V gives us 23a which means it could easily be put on 32a and 4mm, or 25a and 2.5mm no?

Yet it was on 6mm and a 45a breaker.

Just wondering why or if i've got something wrong here.

 

[telectrix]

i would generally fit a cooker appliance on a 32A, 6.0mm, circuit as standard. even if that's a bit over-engineered, it allows for virtually any size appliance which may be fitted in the future.

 

[snowhead]

You'd need to be in the head of the person that did it to inderstand why.

But,
May not have been the original cooker, but used the cable from it.
Cable may have been downrated due to possible heat from back of cooker.
Might have been the only piece of cable in the van.
,,,,

 

[brianmoooore]

That particular cooker might draw a max. of 23A, but it's replacement might draw more., and it's likely that the circuit was installed before the cooker.
No, you can't fit that cooker you fancy, because the supply's not good enough.
No, you can't upgrade your shower, because the supply's not good enough.
No, you can't fit whatever in your garden shed, because the supply's not good enough.
A size or two thicker cable at first fix isn't going to make a great deal of difference to the final bill.

 

[telectrix]

That particular cooker might draw a max. of 23A, but it's replacement might draw more., and it's likely that the circuit was installed before the cooker.
No, you can't fit that cooker you fancy, because the supply's not good enough.
No, you can't upgrade your shower, because the supply's not good enough.
No, you can't fit whatever in your garden shed, because the supply's not good enough.
A size or two thicker cable at first fix isn't going to make a great deal of difference to the final bill.

similar reason I fit a 3 core/E from light switch to fitting. case of a smart switch needing a N, or some other equirement.

 

[pc1966]

The 45A breaker would bother me, unless I know for sure it was clipped direct. Having said that, with diversity allowed for I would doubt the 6mm cable is going to be troubled by any domestic cooker.

 

[Dustydazzler]

6mm is very domestic standard for oven and cooker supplies and has been for donkeys years.

When I rewire kitchens I will pull in 6mm unless I know the exact appliance ratings then I might use 4mm as its obviously cheaper and much nicer to 2nd fix.

Again 32a mcb / 30a fuse was pretty much standard for oven and cooker supplies, but some more efficient ovens the MI state 16amp supply. But again you don't always have the appliance manuals to hand when 1st fixing.

Also don't forget in the olden days we had the old cooker switch with build in 13amp plug socket. But these seem to have fallen out of fashion in more recent years

 

[pc1966]

Also don't forget in the olden days we had the old cooker switch with build in 13amp plug socket. But these seem to have fallen out of fashion in more recent years

I guess a new kitchen is going to have plenty of sockets without it, but it is always handy to have another socket!

My kitchen used to have the isolator for the immersion heater, once I got a combi boiler that was redundant so converted to another socket on 16A radial. Same for the FCU for the old boiler in the kitchen, another socket as part of existing RFC!

Had the muppets who designed/built it originally not built it around the old boiler it could have been removed and cupboard used for something else, like the new boiler? But sadly there was no such plan and I'm not the sort who wants to rip out a perfectly good older kitchen just for that or a minor change in style.

 

[7029 dave]

There are good reasons for up sizing cables, how many threads have been put up where under sizing has been designed and installed and folk come on here to try and find a workaround to the situation.
I understand copper cable is quite expensive but if a circuit is miss designed/ calculated to max it becomes a false spend and a lot of aggravation better to future proof plus also flexibility.

 

[philectrical]

The 45A breaker would bother me, unless I know for sure it was clipped direct. Having said that, with diversity allowed for I would doubt the 6mm cable is going to be troubled by any domestic cooker.

It was free-hanging behind the kitchen units.

 

[kropaske]

6mm is very domestic standard for oven and cooker supplies and has been for donkeys years.

What was standard 20 or 30 years ago may not be today. There are domestic cookers that requires 45A supplies,

 

[littlespark]

similar reason I fit a 3 core/E from light switch to fitting. case of a smart switch needing a N, or some other equirement.

Is that the same reason you fit 1.5 3c & e as legs of a rfc instead of 2.5 t&e….. or was that a genuine mistake?

 

[Deleted account]

Unless it’s a range or a combo of electric oven and hob Combined It’s 4mm for me.

under 3kw oven I’d fit 2.5 mm no problem.

With the current cost of cable I think more installers need to start/thinking along the calculated cable size rather than what’s been done since the 70’s.

obviously it’s worth looking at future proofing for bigger, but 4mm will handle most domestic cooking appliances.
6mm in my opinion is over kill.

 

[nicebutdim]

Unless it’s a range or a combo of electric oven and hob Combined It’s 4mm for me.

under 3kw oven I’d fit 2.5 mm no problem.

With the current cost of cable I think more installers need to start/thinking along the calculated cable size rather than what’s been done since the 70’s.

obviously it’s worth looking at future proofing for bigger, but 4mm will handle most domestic cooking appliances.
6mm in my opinion is over kill.

I get this thinking, but as @7029 dave point out this forum is littered with threads from homeowners who wish the original installation had allowed for the few extra £ of cost involved in fitting a larger CSA cable. If currrent plans continue to be pushed, there'll be fewer gas appliances and more people wishing to fit big, flashy electric appliances.

Same goes for showers - people like convenience and the limitied availability of lower powered showers is testament to the fact that people are minded to opt for more powerful options. Makes sense to at least have the conversation with customers.

 

[philectrical]

I get this thinking, but as @7029 dave point out this forum is littered with threads from homeowners who wish the original installation had allowed for the few extra £ of cost involved in fitting a larger CSA cable. If currrent plans continue to be pushed, there'll be fewer gas appliances and more people wishing to fit big, flashy electric appliances.

Same goes for showers - people like convenience and the limitied availability of lower powered showers is testament to the fact that people are minded to opt for more powerful options. Makes sense to at least have the conversation with customers.

Personally i don't think the push to electricity is going to change how people use their appliances or what appliances they buy. It's probably just going to lead to gas hobs being phased out and replaced with ceramic and induction hobs.

Especially true if energy prices keep rising like they are - people probably won't buy more power-hungry stuff. Most of it will be solar probably anyway by 2030.

 

[Lister1987]

Let's not forget Appendix 17 to consider too

 

[Welchyboy1]

Is that the same reason you fit 1.5 3c & e as legs of a rfc instead of 2.5 t&e….. or was that a genuine mistake?

Ha lol! Done that one in a rush before

 

[telectrix]

Is that the same reason you fit 1.5 3c & e as legs of a rfc instead of 2.5 t&e….. or was that a genuine mistake?

never in my life have i made that mistake. only stock 1.0mm 3c/E anyway.