Question 1

What cable size do I need for a cooker?

Accepted Answer

For most domestic cookers up to about 13kW, a 6mm² T&E cable with a 32A MCB is standard. With diversity applied (first 10A at 100%, remainder at 30%, plus 5A for socket), a 12kW cooker only draws about 27.7A diversified. For larger cookers (14kW+) or where cables pass through insulation, 10mm² may be needed.

Question 2

How does cooker diversity work?

Accepted Answer

The BS 7671 cooker diversity formula from IET On-Site Guide Table 1B recognises that not all cooker elements run simultaneously. Take the first 10A at 100%, add 30% of the remaining current, then add 5A if the cooker control unit has a 13A socket. For example, a 10kW cooker (43.5A) diversifies to 10 + (33.5 x 0.3) + 5 = 25.1A.

Question 3

Is 6mm cable enough for a 12kW cooker?

Accepted Answer

Yes, in most cases. A 12kW cooker draws 52.2A at full load, but with diversity this reduces to about 27.7A (with socket). A 6mm² cable rated at 47A (Method C, clipped direct) is more than adequate. However, if the cable passes through thermal insulation or the ambient temperature is high, derating may push the requirement to 10mm².

Question 4

Do I need 10mm cable for an induction hob?

Accepted Answer

Not necessarily. An induction hob rated at 7kW draws 30.4A, which diversifies to about 21.1A (with socket). A 6mm² cable is adequate. However, if the induction hob is combined with an oven (e.g. 7kW + 5kW = 12kW total), calculate the combined rating and apply diversity to the total.

Question 5

What MCB size for a cooker circuit -- 32A or 40A?

Accepted Answer

A 32A MCB is standard for most cooker circuits where the diversified demand is 32A or less. This suits cookers up to about 15kW. For larger range cookers where diversified current exceeds 32A, a 40A or 45A MCB on 10mm² cable is required. The rule is: diversified demand ≤ MCB rating ≤ cable derated capacity.

Question 6

Does the cooker control unit socket add to the cable size?

Accepted Answer

The socket adds 5A to the diversified demand calculation per the IET formula. This small addition rarely changes the cable size -- it's already factored into standard sizing. For example, a 10kW cooker without socket diversifies to 20.1A; with socket it's 25.1A. Both are within 6mm² capacity.

Question 7

Can I use the same circuit for a hob and a separate oven?

Accepted Answer

Yes. Add the ratings together (e.g. 7kW hob + 3kW oven = 10kW) and apply diversity to the combined total. The diversified current for 10kW with a socket is 25.1A, well within 6mm² capacity. Some manufacturers require dedicated supplies, so always check installation instructions.

Question 8

What cable size for a 14kW range cooker?

Accepted Answer

A 14kW cooker draws 60.9A at full load. With diversity and socket: 10 + (50.9 x 0.3) + 5 = 30.3A. A 6mm² cable (47A Method C) handles this, but many electricians prefer 10mm² for future-proofing and voltage drop margin on longer runs. If the cable route passes through insulation, 10mm² is essential.

Cooker Cable Size Calculator

How This Calculator Works

Quick Reference -- Cooker Cable Sizes

Practical Notes

Frequently Asked Questions