manufacturer's instructions vs common sense!

Eddiesparks · Aug 1, 2014

Ok I know this is dragged up time and time again regarding the 3a fuse on a fan debate but i had an interesting one today.

i am installing a belling 100dft range cooker, the manufacturer's instructions are tight lipped about the actual wattage of the bleeding thing but the info I got was that it needs to be protected by a 32a mcb and also in the manufacturer's data it says that you need to install in 6mm t&e.

The cable run is relatively short, voltage drop is ok and reference method is C - clipped direct - IE clipped direct to a joist with no insulation around it and also chased in for a short run down to the cooker isolator (correct me if i am wrong but this is my understanding of the reference method C), for this reason I decided to go for 4mm t&e protected by a 32a mcb - CCC is 37a so ok for a 32a mcb. Now technically this is against the manufacturer's data but I would claim common sense on this one - the manufactirer's data probably assumes that the person installing may have no idea about cable calculations and could be installing in loads of insulation etc so to save the job of calculating they over spec with the cable size. Would you agree??

Ignoring the "best practice to use 6mm for the future" aspect do you think i was right or wrong
in this instance???

Thanks a lot peoples

Plonker 3 · Aug 1, 2014

It doesn't what is usually selected, it should be properly selected. Why future proof a cooker circuit? Would you install a larger cable for a fan oven just in case?

You tried to justify the manufacturers instructions by saying it will invalidate the warranty, how the hell will that happen if the cable is selected correctly?

Guest77 · Aug 1, 2014

Future proofing lol.

Thats like wiring a socket in 10mm2 cable beacuse one day someone may move into the house and want to connect a welder to the cable lol haha

HappyHippyDad · Aug 1, 2014

Sorry Dillb, No offence meant but I think whatever I say you'll find fault, that seems to be your style. Its ok for you to be wrong sometimes you know. :smiley2:

HappyHippyDad · Aug 1, 2014

MDJ said:
Future proofing lol.

Thats like wiring a socket in 10mm2 cable beacuse one day someone may move into the house and want to connect a welder to the cable lol haha

Come on Mike. What would you generally use for a cooker when your doing a new build?

Guest77 · Aug 1, 2014

happyhippydad said:
Come on Mike. What would you generally use for a cooker when your doing a new build?

A 6mm2 like you fella, but the OP had been told it was only 6.8kw, so he decided to stick a 4mm2 in, no issue with that under the circumstances, admittedly I would use a 6mm2, thats because I don't carry 4mm2 as standard on the Van.

HappyHippyDad · Aug 1, 2014

MDJ said:
Future proofing lol.

Thats like wiring a socket in 10mm2 cable beacuse one day someone may move into the house and want to connect a welder to the cable lol haha

I think all rings should be 10mm, no more discussions on unbalanced rings then :smiley2:

Richard Burns · Aug 1, 2014

happyhippydad said:
I think all rings should be 10mm, no more discussions on unbalanced rings then :smiley2:

You can wire the sockets then!

Risteard · Aug 1, 2014

Eddiesparks said:
in the manufacturer's data it says that you need to install in 6mm t&e.

When I see things like this I always wonder is the manufacturer seriously suggesting that using singles in containment is not acceptable? They shouldn't specify type of cable like that let alone the csa.

ferg · Aug 2, 2014

I've noticed a lot more of the kit I install has " If in doubt consult a qualified electrician"

TBF I do this anyway.

I consult myself, browse the instructions for any new jokes and then do what I feel is the right thing to do.

Engineer54 · Aug 2, 2014

Basically i wouldn't fluff around installing a 4mm cable for a cooker point. The so-called standard arrangement for a typical domestic cooker point, has been 6mm cable with an OCPD of 32A (or 7/044 /30A OCPD) based on upto a 15 KW load, and has been so now for well over 60+ years....

Lucien Nunes · Aug 2, 2014

Exactly... Electrically fine but not a convincing plan overall. While we can concoct all sorts of unlikely 'future developments' that would require 10mm² for the socket outlets, we can predict the future use of a cooker circuit with more certainty. Cookers are usually replaced by cookers, and the next cooker might require 6mm². If the existing cooker turns out to be a poor choice and gets replaced in a couple of years, it would be a shame to have to rewire so soon.

UNG · Aug 2, 2014

happyhippydad said:
I suppose if you do use 4mm and the maufacturers instructions have said 6mm you may invalidate any warranty. Common sense doesn't seem to play much of a part with regards insurance companies!

Infact quite a lot of maunufacturers instructions do seem to say 6mm!

It seems as though you've based the 4mm on this one cooker, which could cause problems for the future when it gets changed. If it was a short run why didn't you just use the standard 6mm Eddie, it would't have been much of a difference in cost?

Ahh that old chestnut I suppose if a long run was needed and 10mm² was used that would invalidate the warranty as well, no doubt we'll have somebody come on and say they would code it as C1 on an EICR as the manufacturers said 6mm² and only 4mm² was installed