More on electric ovens saga

[sidekick]

If a customer has 4mm t/e run from 32a mcb to oven switch with socket.
From there it runs to a FCU behind the oven and fused at 13A.
Cable is in plaster from ccu to ceiling then accross kitchen in ceiling void (no insulation) and back down wall in plaster again.
First question - Is it correct to say clipped direct and 4mm radial ok on 32a mcb.
Second - what is max KW for oven if capacity allowed for socket on oven switch.

 

[telectrix]

design current is 10A + 30% of remaining A + 5A for socket outlet. so if your design current is 30A, the KW can be calculated. at around 10kW. ( 45A ) . so demand, allowing for diversity on 10KW is 10A + 12A + 5A = 27A.

( that's allowing a bit of slack )

 

[sidekick]

design current is 10A + 30% of remaining A + 5A for socket outlet. so if your design current is 30A, the KW can be calculated. at around 10kW. ( 45A ) . so demand, allowing for diversity on 10KW is 10A + 12A + 5A = 27A.

( that's allowing a bit of slack )

Thanks for that. I got same figure when used 11.5kw
11500/230 = 50
10 + 12 (30% 0f 40) + 5 = 27

Should be fine anyway as not many single under unit ovens (if any) come in that high.
Did cross my mind with over caution to put 20A mcb in to cover 4mm t/e but just worried that if oven on full load and kettle in socket that something would then give.

 

[telectrix]

you size your MCB to protect the cable. 4mm ref. method C will carry 32A, so a 32A MCB is fine.

 

[esc]

Hi lads. Does brb pg263 bottom diagram (47) give ref method B, or am i reading that wrong?

 

[telectrix]

doesn't seem to give any other option. must admit, it's something i ain't looked at before.

 

[esc]

Must admit, i stumbled on it. Brings the 4mm down from 36A (clipped direct) to 30A, but as you need it only to carry 27A. . . . .

 

[fivestar]

I think diagram 47 on page 263 applies if cable is run in conduit or trunking in the void - not it it is run loose or clipped

 

[esc]

Cheers for that fivestar. I understand where your coming from, but im not convinced. The descriptions column specifically mentions conduit and ducting when its used, as in diagrams 41, 42 or 1,2,4 and 5 of the previous page. No mention of conduit or ducting is mentioned in diagram 47.