workshop/shed power

[scott25]

Hi he quoted me £750 for doing the job which is all in 55ft I have a rcd in the house cu this is wot he said

30amp in the house cu
6mm 3 core SWA 20meters
5 way cu in shed


6amp for lights
16amp for sockets
6amp for compresser
6amp for welder
Spare for outside lights

Am digging the hole also he said it would cost a lot more with 6mm t&e and a lot more hassle
Does this sound alright

 

[aesmith]

If it were me I'd prefer to have the RCD at the shed, although at our last place it was in the house and we didn't have a nuisance trip in 10 years or so.

6A sounds small for a welder.

 

[JohnW2]

If it were me I'd prefer to have the RCD at the shed, although at our last place it was in the house and we didn't have a nuisance trip in 10 years or so.

Quite. I think that the 'inconvenience value' of having the RCD protection in the house is very much over-played! I can't actually remember anything in any of my outhouses (garage, shed, greenhouse) having ever caused an RCD trip, in best part of 30 years.

In the OP's case, since the supply is apparently coming from a CU, there may be no non-RCD-protected ways available. Of course, when the SWA does not go all the way to the CU (or whatever), as you previously pointed out, T+E feeding it may be buried in walls, hence needing upstream RCD protection.

Kind Regards, John

 

[ban-all-sheds]

The shed is about 30ft max for my back door and 58ft to the cu in the house

Let's call that 10m + 10m, which ties in with the electrician's 20M SWA in the BOM.

he said it would cost a lot more with 6mm t&e

At TLC prices (not the keenest, but they're easy to find)

6mm² 3-core SWA £2.40/m

6mm² twin & earth £2.20/m

So the cables won't cost more, no more glands would be needed, just a box somewhere to join them. Cost a lot more? He's having a laugh - he must have an ulterior motive for not wanting to use T&E for the indoor run.

and a lot more hassle

A lot more? He's having a laugh - he must have an ulterior motive for not wanting to use T&E for the indoor run.

 

[ban-all-sheds]

If it were me I'd prefer to have the RCD at the shed, although at our last place it was in the house and we didn't have a nuisance trip in 10 years or so.

If it were me I'd prefer not to have it on the house CU at all.

6A sounds small for a welder.

I agree.

 

[scott25]

6mm Twin and earth will being conjure from the cu in the hallway under the stairs then thou to kitchen behide the units still in conjure thou as it already there


Ban all sheds how would u have the power to the shed

Wot amp mcb would be for the welder as it runs off 13amp plug

 

[scott25]

And he will not let me surply anything but the thing is I work for Honeywell MK electric so I can get a discount also

That's way am asking for your help on this forum cause £750 sounds a lot to me

 

[ban-all-sheds]

6mm Twin and earth will being conjure from the cu in the hallway under the stairs then thou to kitchen behide the units still in conjure thou as it already there

You should look for alternative speech recognition s/w - if it's rendering "conduit" as "conjure" it's not fit for purpose.

Ban all sheds how would u have the power to the shed

From a switchfuse on the meter tails. And I'd use 10mm cable.

Wot amp mcb would be for the welder as it runs off 13amp plug

Depends on the welder. I assume it's a MIG one? Even ones which barely scrape in as OK on a 13A plug aren't particularly good.

//www.diynot.com/diy/threads/welding-socket-needed-for-17th-edition-board.417054/

Put in a bigger supply and have a 16A circuit for the welder, assuming your supplier will let you.

 

[scott25]

I had me kitchen rewired and its run in conduit from the cu to the kitchen the same route I would like to run my t/e for shed has it been done wrong my kitchen

Gasless mig

Am talk typing thou my iPhone

16amp for the welder

 

[GeoffTitch]

Ban all sheds how would u have the power to the shed
From a switchfuse on the meter tails. And I'd use 10mm cable.

Curious how that works...

You talking about connecting the (25mm) meter tails to a (100A?) switchfuse at the source end, then 10mm SWA out to the garage where it connects to a CU? Can you run from 100A down a 10mm SWA?

 

[RF Lighting]

The clue is in the name switchfuse. It's a switch and a fuse. You select what ever size fuse suits the outgoing cable. It would probably be a 63A for 10.0mm² SWA.

 

[GeoffTitch]

The clue is in the name switchfuse. It's a switch and a fuse. You select what ever size fuse suits the outgoing cable. It would probably be a 63A for 10.0mm² SWA.

Thank you for that

So if it is a 63A fuse, and a 100A switch, it should blow the fuse before it trips the switch? What does the switch do then?

 

[RF Lighting]

The switch is a switch. It does not trip. It is there purely as an isolator should you need to replace the fuse or work on the supply cable for example.

 

[GeoffTitch]

The switch is a switch. It does not trip. It is there purely as an isolator should you need to replace the fuse or work on the supply cable for example.

#

Ah, gotcha. Makes sense now.

So you end up with a 63A fuse before the 63A RCD?

 

[Taylortwocities]

So you end up with a 63A fuse before the 63A RCD?

Ahh, you make a very common mistake.
The RCD's trip rating is a nominal 30mA - where the 30mA is the imbalance that causes the RCD to trip (usually due to a fault to earth).

The 63amp is only the rating of the RCD's contacts. The RCD does not trip or do anything at 63A.