New electrical supply to oven

[Dave Plowman (News)]

If your existing wiring is taking out an RCD like that it wants sorting pronto.

[Dave Plowman (News)]

If you do decide to have a go, label all the cables *as* you remove them from the old fusebox. Magic marker on the sheaths and masking tape labels.

A very common mistake is to 'swop' neutrals between the two busses on a split load box and have RCDs tripping...

If you can't see the sheaths, spend time with a continuity tester and identify which neutral goes with each line, and tape them together until assembly.

[meow2222]

this was the thinking behind their mandation. But the lack of change in electrocution rates doesnt seem to bear it out. There must be other factors at play, its not hard to think of some.

NT

[meow2222]

Borrowed neutrals are fairly common, and dont seem to present a risk in practice. Leaky immersion heaters ditto. Leaky oven elements ditto.

NT

[Dave Plowman (News)]

They might be common with you. ;-)

Neither should be RCD protected. They're both hard wired, and any fault condition should be taken care of by the ECC.

[F]

Much clearer: thanks. Wet finger to check for a tingle?

What do the 'professionals' do? Do they cut the seal? Do they just leave it with no seal when they've finished, or are they able to put a new one on?

Here it is in all its glory:

for the help?

[John Rumm]

;-)

I get the impression most will cut the seal and pull the fuse, then leave it unsealed afterwards. Some don't pull the fuse and work live! A few may book an appointment for the man from the electric company to call and disconnect the supply.

Historically (so I am told) you used to be able to phone the electric company and they would send someone round to reseal it (or make a note to have the meter reader do it on the next visit). These days that does not seem to happen (meter readers no longer being electricity compay employees these days)

it has a fuse on the incoming side. However I would be supprised if this was the main supply fuse that is typically before the meter. Either way it would not help you much in this case because to either replace the whole CU or add a second one you would need to play with the tails that feed the CU (i.e. are before any fuse in the CU)

(The second 30A MCB looks like one of the wylex range designed for their old NN type CUs).

Do you have a RCD anywhere in the house?

Are you able to identify the type of earthing arrangement you have - see here for how:

notice that there are three 5A circuits there. What do these power? (and are any suitable for combining to free up a way)

[John Rumm]

Owner stupidity being one big factor! The fact that they are mandated for new installs does not do anything for all the existing places that don't have them - I expect that is still the majority.

[Andrew Gabriel]

It's plugged in upside down, which is why it's off-centre.

[F]

It all sounds a little casual.

Nothing other than what you see in the image, or what I plug in when I use the hedge trimmer...

TNS? There are two thick green sheathed multi-strand cables connected to the side of the casing of the main fuse next to the meter.

Three separate lighting circuits.

[Dave Plowman (News)]

No, commonly a 45 amp cooker fuse. Old Wylex were made like that.

[F]

Just had a look. 45 amp fuse inside the additional cover with, ooer! 'Cooker' written inside it.

So, I can just have the new circuit wired into it?

No need to take out the main fuse at the meter to do this?

Perhaps replace the fuse with a circuit breaker?

But why didn't the electrician who has just been round to give me a price spot it? He wants to add an additional unit for the cooker.

[John Rumm]

That's handy!

Sounds like it... If you just want an oven circuit then it may have a bigger rating thatn you need and you may find that the fuse it takes is sized such that a smaller one will not fit. Not in itself a problem if you wire it in appropriate sized cable and use a fused connection unit to feed the oven.

As long as the fuse is switched by the CUs main switch, then no.

If it is not a bespoke fitting and can be upgraded like the other fuses then yes you could (although there is not going to be any real benefit in doing so)

Perhaps (like me) he had never seen one of those styles of CU before?

[James Salisbury]

Try takeing the 45A fuse out and see if anything goes off, I am thinking do you have an electricaly heated shower and is this the fuse?

[F]

I'll do that - once I can turn everything like computers and PVRs off first!

No, but I am starting to remember that the (old) kitchen had a cooker point in it when we first moved in 28 years ago! If I'm remembering correctly - it was along time ago - then the point and cable were removed when we built a new kitchen.

[John Rumm]

Aha... sounds like that is a good candidate for where it used to come from then.

[David Hansen]

On Sun, 04 Jun 2006 18:28:19 +0100 someone who may be F wrote this:-

I would switch off the main switch and check that fuse is no longer live. If it is then the new circuit can go there.

I would generally put in a suitable cable for a 45A cooker circuit. The extra cost of the cable is relatively little and it provides future flexibility of cooking arrangements.

In the kitchen there will need to be a protective device suitable for the oven. Do the instructions recommend a fuse? If not, what is the rating of the double oven?

There will need to be a controlling switch within 2m of the oven. This could be in the form of essentially a small consumer unit with a fuse or MCB of say 20A rating. From there a smaller cable could be run to the oven. An alternative is a standard 45A switch with the protective device close to the oven. This might allow for easier conversion later, but it all depends on the layout of the kitchen.

I wouldn't rush into a new consumer unit. Rather I would think through how many additional circuits might be useful and so ensure it has enough spare ways.

[David Hansen]

On Sun, 04 Jun 2006 17:47:02 +0100 someone who may be John Rumm wrote this:-

I assume that the board originally had cartridge fuses throughout, which I would personally have left in place. It may be that the separate fuse was provided because only one 45A fuse should be fitted to that sort of board. Alternatively it may be that because

45A fuses are somewhat bigger than the 30A ones the designers wanted a separate way.

Either way I imagine it is possible to replace the shielding plastic with one of a smaller size that will take the pins of a smaller fuse, should one want to do this.

I haven't seen one either and I'm mildly fascinated by it. However, that is not the only explanation for appearing not to spot it.

[F]

No, the rewirable type.

I've removed the fuse from the board and nothing's gone out.

shows the fuse 'carrier' as removed and it when opened. The 'Electric' you can see is part of 'English Electric'.

Although the flat pins are the same size as the other fuses, they are not so far apart. I assume it can't be exchanged for an MCB(?) as have the others?

[F]

That would be 6.0mm then?

Oven is a double oven Baumatic B904 and won't be delivered for a couple of weeks as we're on holiday as from Wednesday.

However, from Baumatic's site: 'CABLE CROSS SECTION:

3x2.5 mm² minimum, H05 RNF, H05 RR-F insulated twin and earth cable.'

'MAXIMUM LOAD: B904.1SS: 4410 W'

'Fit an all-pole On/Off switch between the appliance and the power supply with minimum contact separation of 3 mm. The switch must be of easy access once the appliance is in place for maintenance and service purposes.'

So, not 6.0mm then?

The 'all-pole On/Off switch between the appliance and the power supply with minimum contact separation of 3 mm' which Baumatic refer to. Is that what I (and Screwfix, item 89530-81) call a cooker switch?

You seem to be saying that I need a cooker switch and a fused connector. Screwfix 81895-81 and 47806-81?

Thanks to everyone for their patience whilst extending my education! Appreciated!