Is this safe ??

[lj329]

Hi Guys,

I have done some rewiring in my kitchen and would appreciate your opinions......

When we moved into the house (about 3 months ago) it had not been maintained for about 20+ years.

In the kitchen there was an old cooker that had an isolation switch that was fitted into the cardboard backing of a topcupboard.

So when I changed the kitchen around, and fitted a new double electric oven, I used a 45amp junction (looks like a blanking plate) with 10mm2 45amp cable and extended the existing cooker cable to a new isolation switch accessible above the worktop.

I then had the problem of getting power to the hood/hob and also the missus wanted the microwave to be postioned above the cooker, to give a whole cooking stuff in one place going on.

Sooooo, I ran a spur using 4mm2 cable from the 45 amp junction to a 30 amp junction box. One leg goes to a FCU that in turn feeds the extraction unit, the ignition for the gas hob and a trailing socking to plug in an underunit fan heater. The other leg feeds a standard socket which I will use to plug in the microwave.

My thinking was that if I don`t put the microwave above the cooker it will sit on the side and plug into the accompanying socket on the cooker isolation switch.

Also it seemed to make sense to have all the cooking stuff off the same circuit

 

[brown-nought]

Oh Boy! Where to start?

1) Is the junction box now on the hardboard?
2) What size was the original cooker supply and its fuse?
3) So you have the double oven, extractor, hob, fan heater (off a trailing extension flex??) microwave and Cooker Isolator socket all of the same wiring?
4) Cooker circuits are for 1 or 2 cookers up to 50A total within close proximity of the isolator switch with optionally one 13A socket on the isolator. But nothing else.
5) Is the hob electric or gas? If gas put it on an FCU off the ring.

So no it’s not safe, allowed or sensible.

If your house has not been maintained for 20+ years get a Periodic Inspection Report before you go any further with the electrics.

 

[josey]

who would be able do give such a report, what does it cover, and aprox how much would it cost

 

[brown-nought]

who would be able do give such a report, what does it cover, and aprox how much would it cost

Any professional sparky who doesn't have spurs.

 

[alertelec]

All of these spurs that you have added, are they fused?

 

[Diyisfun]

Fused but not shod

 

[lj329]

Thanks for the replies.

Brown-n:

1, I have moved the cooker isolation switch into a double socket sunk into the wall above the worktop.

2, The original cooker was cabled on 10mm2 cable, this is wired into a 40amp circuit off the CU.

3, er, yes

4,

5, The hob is gas, so the power is only required for the ignition.

The extractor, hob and trailing flex (running down the back of the kitchen cabinet) are directly off a FCU. The socket (for the microwave) is picked off before the FCU.

There is only one place that I could break into the ring, but only to take a spur. So I could put a double socket in, which I could plug in the heater and microwave. Would it then be ok to leave the spur of the cooker circuit to the FCU to run just the extractor and the ignition for the hob ?

Cheers

Lee

 

[brown-nought]

Cookers, Showers, Heaters and Immersion Heaters all share the characteristic that they draw large constant currents for a long period of time. For this reason they are treated very differently from ring and radial socket supplies that are normal expected to draw low levels of current with occasional blips of high use.

Normally you would have wired the appliances similar to below:-

- Double oven off dedicated cooker circuit with cooker connection switch for isolation.
- Gas hob off 3A ring FCU (accessible above worktop or in cupboard)
- Extractor off 3/5A ring/spurred FCU beside extractor.
- Worktop Microwave plugged into a ring wall socket OR Built-in Microwave off a single socket supplied from a unfused switched spur.
- Fan heater either off an FCU on the ring if seldom used or maybe a dedicated heating circuit if in frequent use.

Your current arrangement has all this off the cooker circuit.

Your plan to spur a double socket for the microwave and heater has two problems. (1) the hob and extractor are still on the cooker circuit (it would be a hard man that would fault 10mm supplied 3A FCU for the hob – but the extractor needs to be separate). (2) The microwave and fan together might overload a double socket.

Have another look and see if you can extend the ring. If the ring cables drop behind the units its normally possible to split the ring without it being visible from above.

However it’s always shame when the electrics have to be retro fitted to a new kitchen.

 

[lj329]

Cheers BN

I will have another look, and get back to this post.

Cheers

Lee

 

[Damocles]

Cookers are not quite the same as water heaters. There is quite a good chance that most of your cooker will be 'off' while you are using it. Applying diversity to your actual cooker might suggest that it could comfortably be run off a 32A or less supply supply. i don't know that, I have not done the sums.

The idea of dedicated supplies it that the thing connected will either be using all the current or none. Hence you can not run anything else off it..

Now it is still considered a good plan to have a circuit dedicated to the cooker, but there is a little room for additions. The big problem is that you are dumping a 40 or so A supply into various bits of equipment without properly fusing down. It is generally not considered a good plan to put a hob igniter on a 13A supply as it is probably wired with cables intended for a smaller fuse. And you can't put a fan heater on a 3A fuse.

If you are thinking of powering sockets, then they should be on a different circuit as there is no limit on what someone inventive might plug in.

 

[lj329]

Thanks for all your replies.

I have discovered that if I take up the bathroom floor I can gain access to the socket ring in the kitchen ceiling, so I am planning to extend the ring to put it two seperate ccts;

one to a FCU to run the hob ignition and the extractor hood,

one to a double socket to plug in the microwave and the heater.


Is this solution OK ??

Thanks

Lee

 

[brown-nought]

Lets start with a couple of clarifications:-

Cookers are not quite the same as water heaters. .

Agreed, the key concept I wanted to establish was the difference between shared and dedicated circuits.

And you can't put a fan heater on a 3A fuse. .

True, I didn’t suggest you can/do – but if its confusing DON’T.

Ok, Lee I’ve re-read your posts and have noticed you other linked post //www.diynot.com/forums/viewtopic.php?t=17415 and I have to say I’m worried that our advice could be leading you astray. In this post you have mentioned ring circuits and in the other 4mm cable. This is normally associated with radial circuits not rings. I’m loathed to say X or Y sounds ok unless we are using and understanding the same terminology. This is my fault for not getting the right information to begin with.

You need to confirm the following. If in doubt use the reference section or call in a pro before you buy, cut of try to fix anything.

1) Type of CU (an your earthing type – see ref section for help).
2) Number of Circuits it supplies (their type, purpose, fuse/breaker rating and what they control).
3) Do you have any RCD protection?
4) General state of the wiring, earth bonding etc.

Also:-

I have discovered that if I take up the bathroom floor I can gain access to the socket ring in the kitchen ceiling, so I am planning to extend the ring to put it two separate ccts;

Are you sure it’s the same ring(?) as the kitchen? Do you have more than one ring?

What exactly did you mean by two “ccts” ?

… one to a double socket to plug in the microwave and the heater.

Beware – as someone remained me last week that a double socket is only intended to take 13A in total. If the fan has infrequent use things should be ok. I’ve also assumed (bad of me again) that the microwave came with a fitted plug (i.e. < 13A) and isn’t a high powered combi unit.

Let us know what you find. In addition to fixing the kitchen wiring it may be worth considering the bigger picture and general state of your wiring. Its obviously easier to cause disruption once and get all the problems fixed than repeated small alterations.

 

[lj329]

Thanks for your replies....

Hi BN

I have had more of a dig around and I must apologise for my less than descriptive previous posts, I was trying to talk like the big boys but can`t quite hack it !

Anyways...

I have looked at my CU and it is a circuit breaker type (not fuse wire). The CB are push in modules with circular breakers that pop out about 5mm when tripped. The earth cable comes out of the CU and attaches to a terminal block on the hardboard mounting panel. There is another earth cable that then leaves this terminal block and joins some copperpipe work.

I have 7 circuits off the CU:

45A for cooker
30A for kitchen sockets (kitchen is an extension)
30A for rest of downstairs sockets
30A for upstairs sockets
20A for boiler
3A for upstairs lights
3A for Downstairs lights - guess what - this circuit also feeds the garage electrics, which we found out when I plugged the tumble dryer in to a garage socket and we were plunged into darkness !!!!

There is no RCD protection.

I imagine the CU needs replacing and have been looking at Crabtree 5+5 MCB types. Is this a suitable model ???????

Now back to the kitchen.

I haven`t yet put up the kitchen coving so if I lift up the bathroom floor (which is directly above) I can see ring 2.5mm cable being fed down into the kitchen sockets.

Now I was planning to extend this ring to put in two more sockets, a single and a double.

Into the single socket I am planning to plug in a 13A plug which will then run to a 3A FCU, which will then power the extraction hood and the hob igntion. This sounds a bit messy but the rest of the kitchen/tiling is done and I want to adapt what I can, safely.

The other socket I was planning to make a double and plug in a standard 800W microwave which is fitted witha 13A plug and a under plynth fan heater which is rated at 2.4kW. This didn`t come with a plug but obviously I will fit a standard 13 A plug. The fan heater is fitted under the cooker unit and I will have to run cable behind the unit (hence my other post about heat/cables).

This solution is far from the ideal, but means I only have to chase a small amount of wall from the ceiling to the top of the tall kitchen cupboard. It will put the cooker back onto a separate, dedicated circuit and put the other devices (hood, hob) etc back onto the kitchen socket circuit ??????

Any thoughts, advice or suggestions is always greatly appreciated

Cheers

Lee

 

[brown-nought]

You don’t need to plug a FCU in. An FCU is essentially like a fixed plug. It can be wired directly into the ring. Its internal fuse protects whatever is on the load side of the circuit.

Do you have any spare tiles?

If it was me and you did I would chop out the tiles below two adjacent sockets on the ring. You could then remove the cable between them by pulling it out from above. Then connect in a new cable to run beneath the units. Normally you will have a space between the back board and the wall. You can then run the cable to FCU’s and sockets to supply your additional equipment (hob, extractor etc) and the return the ring cable to the other socket above the worktop.

You can patch the wall up with plaster and fix new tiles over the fill.

If you are not sure about doing this yourself try getting a pro in as they will have it done in under 1/2 a day. You can discuss the CU options with them at the same time. Everyone wants a bit extra cash before Xmas so finding someone should not be too hard.