Wiring to hob and oven

They basically want you to run a separate circuit from the CU with a 20A breaker on it.

What is the rating of the hob on the data plate? What is the rating of the oven on the data plate?

On Fri, 11 Aug 2006 15:14:32 GMT someone who may be Bob Martin wrote this:-

Both electric, presumably.

What do the instructions for the oven say about the rating of the protective device for that?

Is there anywhere suitable to place a small two way consumer unit?

By "fuse box" I presume you mean a fused connection unit.

Assuming clipped direct installation conditions apply, the rating of 2.5 mm^2 cable is 27 A. If the max. load of the hob doesn't exceed this figure (= 6.2 kW) the cable cannot be overloaded. If that is the case

Reasoning:

1. The 2.5 cable is a short run and will be adequately fault protected by the 32 A breaker (c.f. an unfused spur on a ring circuit), and overload protection for that cable is not necessary, as established above.

1. If the total cooker load is 60 A, applying the standard domestic cooker diversity rule requires the circuit design current to be the first 10 A, plus 30% of the remaining 50 A (= 15 A), plus 5 A for the socket-outlet, i.e. 30 A total, which is satisfied.

Bob

Does the domestic cooker diversity calculation (10A+30%) apply equally to "separates" and a "traditional" combined cooker? I'm interested in this since I'm at the initial thinking stage of remodelling the kitchen, and pondering a separate double oven and hob. Almost certainly the existing feed will be inadequate - it's a 32A MCB feeding a (I think!) 4mm cable to a CCU which has a 13A socket (only currently (sorry) used for a fridge/freezer). I'll certainly do away with the CCU as I want a separate non-RCD feed for the f/f.

Where else would you (normally) wire a hob and oven?

What's a "Prescott" anyway?

On Fri, 11 Aug 2006 21:47:16 +0100 someone who may be WiseOldSage wrote this:-

Why?

I don't see why not, nor have I ever seen any official or quasi-official guidance to the contrary. Of course if you have reason to suspect that the loading will be higher in a particular situation then you must design appropriately.

Eyebrows will be raised if you don't upgrade the cable to 6 or 10 mm^2. 4 mm^2 is actually OK for 37 A (clipped direct, no grouping, 30 deg. C ambient and no BS 3036 rewireable fuse) but the voltage drop and Zs calculations might lead to quite a short max. circuit length. It's something of a hint that the combination of a 30 A OPD and 4/1.5 mm^2 cable does not appear in the table of conventional circuits in the OSG (Table 7.1).

I agree that CCUs with sockets should be consigned to the bin - and indeed to history - and doing that does give you another 5 amps to play with on the diversity calc., allowing another 16 A or so of MD.

I's a processor chip surely?