Opinions on the load of this cooker circuit???

[Joe S]

I have been to look at a job tonight for a new oven to be installed. The circuit is a 6mm T&E with 32a MCB. The appliance end of the circuit has the Electric hob (5.7kw) wired into a Cooker connection point and it also has a spur in 2.5mm for the old oven which has been binned. They have bought a 3.5kw Oven as a replacement but according to the diversity calc the total Load is 35.2A. They are talking of a Gas hob in the future. Would you run another circuit to accomodate the oven or get them to buy a gas hob now???

Thanks alot.

 

[Guest55]

what diversity ?
show us your maths
;-)

 

[rattlehead85]

Well give them the choice! If you have done the calcs and proved the existing circuitry is insufficient you explain this and give them the options. If they refuse new circuitry or decide against fitting the gas option then you turn around and walk away. Let some other mug put his name on the line if they want an incorrect job.

 

[MDJ]

Have to agree haha, diversity you say?

 

[Joe S]

First 10A of the load, 30% of the remainder then add 5A if a CCU with single socket. I have no single socket above w/top.

 

[MDJ]

I have had a hard day, however My calculation is a lot less than that.

 

[Joe S]

My fault, my day was obviously harder than I thought, lol! I make it 31A which is fine. I thought my original sounded wrong which is why I jumped on here. Sorry fellas

 

[telectrix]

dump the 2.5mm. fit a dual CCU on the 6mm from the isolator, cable to each in 6mm or 4mm. sorted. allowing for diversity , your current demand is 20A, or 25A if the isolator has a socket outlet.

 

[Rampantchilli]

i must be wrong then, i worked it out to 19A with out a socket.
5700 + 3500=9200
9200/230= 40
10A+
30%of (40A -10A)=
19A

mind you, my kitchen fitter always said i had a magic calculator

 

[telectrix]

give you that. i did it in me 'ed and used 1/3 of the 30A to make it an easier calculation.

 

[Guest55]

My fault, my day was obviously harder than I thought, lol! I make it 31A which is fine. I thought my original sounded wrong which is why I jumped on here. Sorry fellas

too late !!! the customer has already fitted gas instead lol.

 

[MDJ]

good point about the socket outlet Tel, I actually forgot that, I worked it out at around 19 amps, but it could be 24, either way not 35 haha

 

[telectrix]

if E54 was reading this he'd say a 32A fed 6mm is good for 15kW cooker and has been since he left school 60 years ago.

 

[Joe S]

i must be wrong then, i worked it out to 19A with out a socket.
5700 + 3500=9200
9200/230= 40
10A+
30%of (40A -10A)=
19A

mind you, my kitchen fitter always said i had a magic calculator

Is that how the calc should be done?? My old boss taught me the other way which is how I came up with 31A

 

[telectrix]

that's spot on. but i ( for some reason known only to my psychiatrist ) use 33%, not 30%.

 

[MDJ]

whatever the actual way is Joe your fine with that load on a 6mm2 cable buddy, no worries at all, unless it is 2 miles away from the Dist board of course haha.

 

[telectrix]

that's spot on. but i ( for some reason known only to my psychiatrist ) use 33%, not 30%. ah. i've remembered. it's because we now use 230V instead of what it actulally is, 240. just to err on the cautious side.

 

[telectrix]

whatever the actual way is Joe your fine with that load on a 6mm2 cable buddy, no worries at all, unless it is 2 miles away from the Dist board of course haha.

but it'd be OK at 1 mile 7 furlongs and a chain. just be a bit longer to cook stuff.

 

[MDJ]

Hahaha

 

[Joe S]

25a just seems low to me. Just means that all my circuits have been super safe, lol!!

 

[telectrix]

better safe than up before the man in the funny wig.

i once had to go to court . magistrate said " have you been up before me before? i said " don't know, your worship. what time do you get up?"

 

[MDJ]

You could work out the load by dividing it by 0.4, some do, if you do it will be about 16 amps haha

 

[Joe S]

I nearly spat my tea out at that!!!:laugh3:

 

[telectrix]

divide by 0.4? that would be 40/0.4 = 100A better get the 25mm out. sorry mike. couldn't resist that one.

 

[MDJ]

sorry x (times) lmao, that was a blooper haha

 

[Guest55]

25a just seems low to me. Just means that all my circuits have been super safe, lol!!

i've managed to squeeze all 25 circuits on the entire first floor of a retail installation design down to a tiny , winey , measily 48amps per phase

i used a man's man's diversity ;-)

 

[Rampantchilli]

Is that how the calc should be done?? My old boss taught me the other way which is how I came up with 31A

not sure if thats the way to do it, but i just follow whats taken into account in the order its mentioned.

another thing that is so rarely taken into account is reference method, by the regs almost none of the reference methods allow 32a on 6.0mm except perhaps ref c,
i think 101 or 102 would still be ok for the load but not sure off the top of my head

 

[telectrix]

worst is 103 at 23.5A.

 

[IanHug]

Excuse this question if it's stupid but isn't diversity used to get a rough estimate where not all outlets will be used at the same time? Isn't it quite likely that the oven and all hob rings will be on at the same time and cause a maximum load?

 

[telectrix]

not exactly, cookers are a one off, inasmuch as 1. not everything will be switched on at the same time. and 2. the rings and oven elements are thermostatically controlled, so that, even when all are on, they will not all be pulling full load at the same time.

 

[SAILOR48]

Excuse this question if it's stupid but isn't diversity used to get a rough estimate where not all outlets will be used at the same time? Isn't it quite likely that the oven and all hob rings will be on at the same time and cause a maximum load?

Your right mate
Probably Only at Christmas though ,with a kettle plugged in as well, maybe a bit of low voltage depending where you are.
Typical of the “experts” on here just quote the book don’t use any common sense.

 

[MDJ]

They may all be on very rarely but I doubt they will all be on max, almost unheard of unless the wife cannot cook properly LMAO

 

[Des 56]

Put the oven on and put all the rings on maximum
I can assure you,it will not draw current that would equate to the sum total rating of all the rings and oven

 

[MDJ]

Your right mate

No, No he's not

 

[SAILOR48]

They may all be on very rarely but I doubt they will all be on max, almost unheard of unless the wife cannot cook properly LMAO

What if they were?

 

[MDJ]

Never Happen, your trying to start a discussion over a near impossible situation

 

[Jay Sparks]

Never Happen, your trying to start a discussion over a near impossible situation

Abit like Spurs winning the Prem league!!!!!!!!

Sorry Mark..lol


Jay

 

[SAILOR48]

Never Happen, your trying to start a discussion over a near impossible situation

With respect
No sorry that’s not my intention, the point I am trying to make is that the book is only a guide and certain things should be taken in to consideration when assessing a situation.
Diversity is a judgment not an exact science and I feel that just doing the maths is not enough.
Where I live we still have abnormal low voltage on certain parts of the island, this must be considered, its not in the book.
Right off you lot go, pick the snot out of that, I have put my tin hat on.

 

[Des 56]

Abit like Spurs winning the Prem league!!!!!!!!

Sorry Mark..lol


Jay

Forget the big names of today like Man utd etc
When Spurs won the double,they were thought of by me and many others as the Aristocrats of football,the best,living football legends,l,the ultimate football team and I was a young kid and not even one of their fans :clap:

 

[MDJ]

Na can't be arsed M8, as It happens I am hands on and site man not a regs man, and only 5% of my work domestic, but a cooker is something which diversity can be allowed and thats the end of the matter, the book is irrelevent, it's just an obvious choice for the spark designing the load in a house, no need to attempt to scrutinise this point down to what ifs and maybes, pointles, carry on by all means I will enjoy the banter for sure, and the way you carry on it will follow you around.