5.3 kw double oven on a 20 amp fuse with 2.5 cable

[TaffyDuck]

yet again....looking at the appliance first...or if the appliance isn`t on site at the time of design....then gathering info (make model) etc from the client and doing a bit of research on it.....find out the KW rating etc...so as to calculate/design accordingly....isn`t that the difference between installers and electricians.......

Couldn`t agree more, installers would go with 2.5 electricians with 6mm.

 

[GLENNSPARK]

Couldn`t agree more, installers would go with 2.5 electricians with 6mm.

no...too cut n dry for me this....electricians would go with the APPROPRIATE SIZED CABLE and associated overcurrent device at origin for the expected load.....after diversity.......

 

[TaffyDuck]

no...too cut n dry for me this....electricians would go with the APPROPRIATE SIZED CABLE and associated overcurrent device at origin for the expected load.....after diversity.......

I couldn`t disagree with you more in this particular instance. I`m not saying wire a lighting circuit in 10mm. What I am saying is for the sake of a few extra quid you have numerous advantages. The cable is under-stressed consequently it will not degrade so quickly, if the oven is used at full load the MCB wont trip, if the client upgrades the oven or redesigns the kitchen in a few years you have the redundancy in the circuit to handle it (or to add a hob in the redesign scenario) without pulling the house apart. disadvantages are that it costs a couple of quid more now (cheaper of course to going back in a years time to upgrade it).

OSG is, i concede, guidance and it specifically states that the installer can use these calculations or his own judgement at his discretion.

My discretion points me to the option of 6mm on a 32amp MCB. Yours to 2.5mm with none of the advantages stated above.

We`ll agree to disagree on this one

 

[GLENNSPARK]

I couldn`t disagree with you more in this particular instance. I`m not saying wire a lighting circuit in 10mm. What I am saying is for the sake of a few extra quid you have numerous advantages. The cable is under-stressed consequently it will not degrade so quickly, if the oven is used at full load the MCB wont trip, if the client upgrades the oven or redesigns the kitchen in a few years you have the redundancy in the circuit to handle it (or to add a hob in the redesign scenario) without pulling the house apart. disadvantages are that it costs a couple of quid more now (cheaper of course to going back in a years time to upgrade it).

OSG is, i concede, guidance and it specifically states that the installer can use these calculations or his own judgement at his discretion.

My discretion points me to the option of 6mm on a 32amp MCB. Yours to 2.5mm with none of the advantages stated above.

We`ll agree to disagree on this one

i have throughout this thread mentioned the use of diversity.....now then...where have i quoted the specific use of 2.5?....

 

[TaffyDuck]

Post 41 &42 dont start back pedaling now.

 

[Spudnik]

NO. 10A + 30% of remainder (13A, not23A)

Agreed, however, the old 17th regs book and OSG are different from each other

One says 30% of remainder and the other says 30%.

Not sure which way round though.

 

[TaffyDuck]

Glad that you`ve come round to my way of thinking though ;-)

 

[GLENNSPARK]

Post 41 &42 dont start back pedaling now.

post 41 and 42?.....I see that your fairly new to the forum Taffy.....well its good to have you on board.....but please feel free to take a look at previous threads i have posted on...stick around for a while ....i think you will find i dont backpeddle on anything...lol......

 

[TaffyDuck]

Agreed, however, the old 17th regs book and OSG are different from each other

One says 30% of remainder and the other says 30%.

Not sure which way round though.

As i understand it one says something like 10 amps and 30% of remainder and one says 10 amps and 30% of full load above 10 amps, which I think is the same thing. May be wrong here but I think its one of the many examples of confusing tech speak in BS.

 

[TaffyDuck]

post 41 and 42?.....I see that your fairly new to the forum Taffy.....well its good to have you on board.....but please feel free to take a look at previous threads i have posted on...stick around for a while ....i think you will find i dont backpeddle on anything...lol......

Yes mate I am ;-) ever thought of taking up a career in law?

 

[GLENNSPARK]

Yes mate I am ;-) ever thought of taking up a career in law?

nah....your allright........would soon get bored........funnily enough...you remind me of someone who has recently vacated this forum.....lol.....sounds familiar like...lol......

 

[TaffyDuck]

nah....your allright........would soon get bored........funnily enough...you remind me of someone who has recently vacated this forum.....lol.....sounds familiar like...lol......

Who`s that? Seriously no idea who your talking about

 

[GLENNSPARK]

Who`s that? Seriously no idea who your talking about

well its for me to know mate....lol....but i guess that a few others in here will already have an incling of who i am refering to....lol.....

 

[TaffyDuck]

well its for me to know mate....lol....but i guess that a few others in here will already have an incling of who i am refering to....lol.....

well I dont have a clue, but there you go.

 

[SimpleSimon]

Glennspark makes great points time and time again, and in this case he's not wrong. However I think there are two sides with this story.
Yes you can calculate and use diversity to install the appropriately rated cable, this is the correct way to do it taking all factors into consideration.

But.. (and this is the way I like to do it) with an oven we know that in the future there could likely be installed a bigger/more powerful oven, or a bigger family in the house so for ease of future install install a bigger cable that would hopefully take that larger future load. This is what I do so once that cables in there's no thought of it being upgraded for sake of being an underrated cable.

:21:

 

[GLENNSPARK]

yes but even then you can go up a CCC in cable...after diversity has been taken into account.....so, say what could be ample (2.5) for instance this CSA after calculation..not guesswork....so say a 2.5 could then become a 4.0mm for the purposes of future proofing.....so if you start with 6.0mm CSA...then decided to futureproof that...whats it then?....10mm CSA...?....thats 64A for method C...(clipped direct).........totally ridiculous ...not to mention unneccesary.....anyway.....you follow the manufacturers instructions first....they take presidence........

 

[TaffyDuck]

yes but even then you can go up a CCC in cable...after diversity has been taken into account.....so, say what could be ample (2.5) for instance this CSA after calculation..not guesswork....so say a 2.5 could then become a 4.0mm for the purposes of future proofing.....so if you start with 6.0mm CSA...then decided to futureproof that...whats it then?....10mm CSA...?....thats 64A for method C...(clipped direct).........totally ridiculous ...not to mention unneccesary.....anyway.....you follow the manufacturers instructions first....they take presidence........

You really should go on a 5 week course and then you would fully understand that Diversity are a dance group from Britain`s Got Talent. ;-)

 

[GLENNSPARK]

only talent i see is when were going past the uni`s here in leeds......loads of fit student birds hanging around the "halls of residence"......yummy.....:drool5:

 

[Engineer54]

Diversity on a cooker works fine until Xmas day when they trip out. personally I think regs are out of date on this one. Take a 10 kW electric range cooker. 10kW/230V= 43 amps. 10 amps plus 30% remaining load (approx 9.9amps) =19.9 amps so 2.5mm twin and earth on a 20 amp, dont think so. "At the installers discretion" is a term we ought to use more. On top of that you`ve got an appliance that draws for long periods of time allowing heat to build up in the circuit. Its not like a kettle that runs for a couple of minutes at a time. 6 or 4mm on this OP specs every time for me,

Never once heard of an electric cooker tripping out because of diversity being applied.
The cooker diversity formula works for cookers upto 15KW. It's been around now for 60 years, Because it WORKS and it is, no-way out of date. As i've so often stated on these cooker theads, the manufacturers always state the connected load, not the ''maximum load'' which, is always going to be smaller...

The oven elements will not be on constantly, they are all thermostatically controlled, so it's an on and off situation for the duration once upto tempreture...