Cooker cable sizeq

[androiduk2002]

splitting hairs here guys sorry, at college we worked out an 8k cooker at college and was told we could use diversity, one thing that isnt said tho is has the cooker switch got a socket on it or is it just a switch ?

I might be wrong here but here goes

9000/230 = 39.13A lets call it 40 A

40X30% = 12A

12 + 10 = 22A + 5A (if socket cooker switch unit)

27A for the load of the cooker. Pray Pray Pray

By all means if I am wrong please kick me and tell me so and I will :coat :coat :coat

 

[PC Electrics]

Diversity calcs this to be 24A if there is a socket on the control.

(remember its first 10A plus 30% of remainder plus 5A for skt)

The OSG guidance is that a 32A / 6mm circuit is adequate for up to 15kW of cooker in the domestic arena.

So the cooker would be fine on a 32A/6mm circuit.

However, although it is extremely unlikely that the cooker will ever have the oven(s) and all rings switched on full all at once, it should be noted that a BS5871 type 2 30A will trip in approx 250 secs with a load of 38A (from curves in 15th edition). So for peace of mind (and while you're there it's very little extra cost or effort) you might consider changing the MCB for a 32A type B.

 

[androiduk2002]

Diversity calcs this to be 24A if there is a socket on the control.(remember its first 10A plus 30% of remainder plus 5A for skt)

The OSG guidance is that a 32A / 6mm circuit is adequate for up to 15kW of cooker in the domestic arena.

So the cooker would be fine on a 32A/6mm circuit.

However, although it is extremely unlikely that the cooker will ever have the oven(s) and all rings switched on full all at once, it should be noted that a BS5871 type 2 30A will trip in approx 250 secs with a load of 38A (from curves in 15th edition). So for peace of mind (and while you're there it's very little extra cost or effort) you might consider changing the MCB for a 32A type B.

I see where we have got a differance I used table 1B from page 97 OSG you used table 1A from page 96 , on table 1B they say to use 30% of full load of appliance + 10A + 5A for a socket.

 

[PC Electrics]

Table 1B says:

"10A +30% f.l. of connected cooking appliances in excess of 10A......

In other words it says the same as 1A.

 

[androiduk2002]

"In excess" means a 3 amp differance be interesting to get others views on which table or if we are both correct, this is what I love about this forum

 

[SPECIAL LOCATION]

"In excess" means a 3 amp differance be interesting to get others views on which table or if we are both correct, this is what I love about this forum

The two tables... 1A (pg 96) & 1B (pg 97), {just to remind those at the back of the class flicking elastic bands at each other.. yes Patch thats you we are talking about!!!!} ... the two tables are very subtlety different..

In as much, if you read the associated bits of text staring on page 95,

Table 1A is relating to demand / diversity calculations for outlets on individual circuits.

and

Table 1B is relating to the Max demand of an installation, (paragraph 4 on Page 95), by using diversity calcs per circuit type.

e.g. look at the description for the lighting circuit,

1A refers to a lighting outlet

1B is a lighting circuit.

back to our Cooker.

1A is a Household cooking appliance

1B is a cooker circuit... that could, although not very common, have more than one appliance on it.

so If you only have one appliance on the circuit

1A & 1B should be about as near as damit the same.

Guinness

 

[tom1]

while we are on about cookers and diversity i may soon have to install a 15.6kw range cooker, the current cooker is on a 32 MCB and 6mm cable, thinking about changing too a 40 amp but i might just see what happens;\

 

[SPECIAL LOCATION]

while we are on about cookers and diversity i may soon have to install a 15.6kw range cooker, the current cooker is on a 32 MCB and 6mm cable, thinking about changing too a 40 amp but i might just see what happens;\

Page 106

Appendix 8.4

guidance suggests a 30A /32A is usually appropriate for a cooker up to 15.0K

I doubt the extra 600watts would cause major problems?

I would probably leave it on 32A myself but mention to the customer it is just about borderline and may need upgrade if problems occur.

Just a minor thought... is the 15.6K rating quoted for 230v OR 240v

(remember a lot of showers have power quoted at 240v!)

e.g.

15600 @ 240v = 65A, diversity = (10A+(55A x 0.30))= 26.5A

15600 @ 230v = 67.8A, diversity = (10A+(57.8 x 0.30))= 27.34A

Not a fat lot of difference.. but can be worth checking when figures are near max recommended tolerances.

Only other point how long is the cable run?

Typical cookers well under 50m should be no problem...

but a 50m 6.00mm T&E @ 32a has a volt drop of

(50 x 7.3 x 32) / 1000 = 11.7volts

starts getting close to the 5% max volt drop figure 11.5v

 

[androiduk2002]

The two tables... 1A (pg 96) & 1B (pg 97), {just to remind those at the back of the class flicking elastic bands at each other.. yes Patch thats you we are talking about!!!!} ... the two tables are very subtlety different..In as much, if you read the associated bits of text staring on page 95,

Table 1A is relating to demand / diversity calculations for outlets on individual circuits.

and

Table 1B is relating to the Max demand of an installation, (paragraph 4 on Page 95), by using diversity calcs per circuit type.

e.g. look at the description for the lighting circuit,

1A refers to a lighting outlet

1B is a lighting circuit.

back to our Cooker.

1A is a Household cooking appliance

1B is a cooker circuit... that could, although not very common, have more than one appliance on it.

so If you only have one appliance on the circuit

1A & 1B should be about as near as damit the same.

Guinness

Thanks for explaining the differance Special :^O :^O one little question if the switch has a socket on it would that count as another appliance on the circuit I.E. if you had a fridge plugged into the socket or would it only count if there was a spur off the cooker switch ?

 

[Lurch]

Thanks for explaining the differance Special :^O :^O one little question if the switch has a socket on it would that count as another appliance on the circuit I.E. if you had a fridge plugged into the socket or would it only count if there was a spur off the cooker switch ?

If there is a socket on the switch (called a cooker control unit, or CCU ) then there is a fixed allowance of 5A for that. If there was a socket spurred off the cooker circuit for general use then it isn;t an allowable outlet under BS7671, so it doesn;t have a table for it as it shouldn;t be there.

 

[tom1]

thanks for that replie specs it's a very good post, the run looks only to be 10m tops, no rcd but the cable runs under the floor and will >50 if i have to move it,

i doubt they will have it on full all day, not a big houes or family

not seen the cooker yet, its for a kitchen fitter and all they get is a sheet with different appliances on it gives the kw and fuse size, this one says 15.6kw and 45 amp fuse, but like you say i will prob stick with the 32 unless it says different in the instructions

 

[androiduk2002]

If there is a socket on the switch (called a cooker control unit, or CCU ) then there is a fixed allowance of 5A for that. If there was a socket spurred off the cooker circuit for general use then it isn;t an allowable outlet under BS7671, so it doesn;t have a table for it as it shouldn;t be there.

So if joe bloggs happened to have 2 cookers in his home and you run the one circiut to serve both then use table B other than that table A

 

[Lurch]

So if joe bloggs happened to have 2 cookers in his home and you run the one circiut to serve both then use table B other than that table A

I think that would fall foul of other limitations within BS7671. AIUI, you can have 2 appliances on 1 cooker circuit (e.g. built in oven and hob above) but not 2 separate cookers in separate locations, so again as it doesn't comply then no table applies.

 

[androiduk2002]

Now i get you Pray so if table B is to do with built in appliances more than free standing ? Sorry to be a pain a Lurch

 

[Lurch]

You've made me break the books out now. Reading......

Now i get you Pray so if table B is to do with built in appliances more than free standing ? Sorry to be a pain a Lurch

I'm struggling to put this into words, every time I write something it makes no sense.

 

[androiduk2002]

Tis all very confusing and I am a trainee we only touched it briefly in a pratical , which seems to be well ahead of the theory at the moment, which is adding to more confusion.

Blushing Blushing

 

[SPECIAL LOCATION]

I think that would fall foul of other limitations within BS7671. AIUI, you can have 2 appliances on 1 cooker circuit (e.g. built in oven and hob above) but not 2 separate cookers in separate locations, so again as it doesn't comply then no table applies.

Page 160 OSG two or MORE cooking appliances can be supplied..

a -al 2+more = 3 or greater

 

[Lurch]

Page 160 OSG two or MORE cooking appliances can be supplied..a -al 2+more = 3 or greater

But only if they are within 4m of each other, in the same room.

 

[SPECIAL LOCATION]

So if joe bloggs happened to have 2 cookers in his home and you run the one circuit to serve both then use table B other than that table A

Circuit between 15A & 50A can supply two or more appliances in the same room.

One switch can isolate two appliances providing both appliances are within 2m of the switch.

If more than 2m away from switch need individual isolator switches..

but can still be on same circuit provided power ratings and cables sizes etc.. are OK.

Reading:

On site guide Page 160 8.4 Cooker circuits in household and similar premises.

Guidance note 1 Selection and erection Page 131 C.4 cooker circuits in household premises.

the only reg referred to by the Guidance Note 1 is 537.5.1.3 page 121 BRB,

which relates to appropriate function switches.

 

[SPECIAL LOCATION]

But only if they are within 4m of each other, in the same room.

Or furthur apart on separate switches