Two Steps Forward One Step Back!

[alba2]

Every time I seem to have a solution to routing cable from the CU to a newly sited single oven and combination microwave, there is a setback.

The latest problem is that the Ashley & Rock CU, despite its modern specification is no longer made, or catered for in terms of mcb's.

After much searching I think I have found substitute mcb's, but need to check that my calculations are correct before I order them, and waste money.

The pyrolitic oven max load is 3.5 kw. Electrolux state a 16 amp fuse.
The combination MW is 3.4 kw and they state a 15 amp fuse (although originally I was mistakenly told 13 amp).

I am now proposing a 10 metre run of 2.5 mm cable for each radial, with 2 x 16 amp mcb's in the CU. I can't get a 15 amp mcb.

The cabling will run partly through plastic conduit, stud and plasterboard partitioning, and under a chipboard floor.

Should I up the cable to 4mm or 6mm? Is it OK to use the 16 amp mcb
for the microwave? I calculate the load to be 14.78 amps.

Thanks

 

[Taylortwocities]

The mcb in the consumer unit is there to protect the CABLE.

2.5mm² T&E will be fine for 16amp. That's a common arrangement for a radial circuit.
You may need to derate as the cables will be GROUPED in teh conduit. you'll have to do the maths-can't be bothered this time on a Sunday night!

Don't forget you'll need a double pole isolator for each circuit within 2 metres of the appliances.
20amp switches will be fine for those.

 

[alba2]

Taylortwocities,

Thanks for your help.

However, as I said 2 steps forward and one back. It is an Ashley & Rock CU and the MCB's are no longer available.

A thread on this site recommended Merlin Gerin MCBs so I bought them and they almost fit, but not quite. The prongs on the bus-bar are slightly too large to fit into the two holes. The existing MCB's have a slot.

 

[ericmark]

In theory consumer unit is a type tested distribution board and as such they have to have only item recommended by manufacturer installed.

In the real world of course people try to get things to fit however when you have the next PIR the electrician could well fail it.

Consumer units are cheap it is only the bits inside which are expensive and you really have to be careful when spending money on obsolete gear.

There are normally a few options including adding a second unit. Since consumer units are notifiable under Part P likely to get every thing right cheapest way is to get a spark to do job for you.

Have you tried http://www.thefusecompany.co.uk/ as they may have the correct MCB's for your CU.

 

[alba2]

Thanks,

There is plenty of work here. Difficult to get any trade, sparks included.

You phone and leave a message and they don't even return your call.

 

[sparky716]

Why's that alba are they too busy or do they not want the work up there ???

 

[alba2]

Why's that alba are they too busy or do they not want the work up there ???

As I said, there is plenty of work, and it has been that way for decades. The so called recession is not biting here.

A friend had his kitchen extension postponed 3 times from May. Eventually it commenced in October. Once again he felt he had no choice.

You can't get most trades, and when you can it is often rip off prices, as are many other prices in this area, like restaurants etc. I have been ripped off a number of times.

A tiler quoted me £250 for some tiling in the bathroom. he said it would be an all day job. I got a phone call from him at 11am to say he was finished! Yet he still wanted his money. I had given him the keys and he said he started at 5 am, which I could not prove. The finish was not as good as I wanted, but I had difficulty getting him in the first place.

I managed to get an electrician to call tonight to give me a quote, but I was not impressed.
He was considering running a cable from the existing cooker outlet across the kitchen to feed a newly sited oven and mw. A 7.5kw induction hob is to remain at the current position and a 3.5 kw oven and 3.4 kw combi mw at the new position. This total load would be coming from the existing cooker outlet if that was his plan! Rather excessive? Yet he did not even check the capacity of the existing wiring at the cooker outlet. He said he would have to do some calculations. I would have thought he could have made that decision right away.
When I suggested 2 new radial circuits from the CU concealed inside ceiling coving, he could not tell me if this was within the regulations.
He did not even open the CU to check whether there was sufficient space for extra MCB's.
Either he did not want the work or was incompetent in my opinion.
I feel I could do a better job myself, but I want to stay within the regs and employ an electrician.
Now I have to wait until the beginning of the next week to get his quote, for a fairly simple job.

 

[ban-all-sheds]

I want to stay within the regs and employ an electrician.

Don't forget the regs are different in Scotland. There is much talk of Building Regulations and Part P here because most of us are in England or Wales.

Make sure you aren't mistakenly employing an electrician where not mandated by your laws.

 

[alba2]

I want to stay within the regs and employ an electrician.

Don't forget the regs are different in Scotland. There is much talk of Building Regulations and Part P here because most of us are in England or Wales.

Make sure you aren't mistakenly employing an electrician where not mandated by your laws.

The regs are just as strict here. We also follow IEE regs.

 

[ban-all-sheds]

I'm not talking about the Wiring Regulations, just the situations where you need a Warrant.

 

[sparky716]

Maybe we should start travelling north instead of south lol

 

[alba2]

Maybe we should start travelling north instead of south lol

They need some competition up here.

I still have not got an electrician.