Garage/workshop CU arrangements

[Lobster]

Hoping to start on wiring up my garage/workshop fairly soon, and just want to check on my CU etc.

This outbuilding (detached but next to the house) already has power, in the form of a cable from a dedicated 30A MCB in the house's split-load CU, in which all but the lighting circuits are protected by a 30mA trip RCD. Earthing is TN-S. Cable runs through the house and connects to SWA inside a metal box in the kitchen; SWA then runs underground to the outbuilding where it connects (via another metal box) to a CU out there.

The outbuilding CU is pretty old; it has two circuits with cartridge fuses (30A and 5A) for power and lighting respectively. Power is currently provided to one double socket only, used for our 'overflow' fridge and freezer.

I'm intending to extend the single radial circuit into a ring, which will have 5 or 6 double sockets to power usual workshop tools and chargers. Nothing particularly heavy duty; just standard drills, grinders, saws etc.

So, finally the question: is my current outbuilding CU up to the task, and/or is their anything to be gained (safety wise) by upgrading it? I'm not anticipating lots of nuisance trips so I don't mind having to reset the house RCD on rare occasions if need be. Also, I particularly don't want any risk of nuisance trips of any upgraded garage CU causing the garage freezer to thaw out without me being aware of it!

Thanks David

[Tabby]

Sounds like you need the standard arrangement: slate fuseboard mounted on wood plinth suitable sizes of tinned copper wire as fuses both poles fused of course, yo cant rely on which supply wire's live knife switches you can make with workshop tools Conductors of copper or iron cable insulation not necessary if you mount the cables on standoffs overhead sockets: anything you like really, ES lampholders are as good as any Don't forget some Nernst lighting, or perhaps the new fangled carbon filament lamps.

NT, 1880

[Owain]

You back on the smooth sippin' laudanum again, NT?

Owain

[ARWadsworth]

It sounds legal to me:-)

I probably would swap the fuse box for a simple CU such as

you want to move the garage supply to the non RCD side of your house CU and use RCBOs in the garage CU with the freezer on a MCB.

[Tabby]

hehe :) Are you saying the only sensible choice is Moore's tubes?

[Owain]

I like Moore's tubes and somewhere have the instructions for them ...

Owain

[Tabby]

What really struck me about them is that one lamp can be a couple of hundred feet long. Good for efficiency, but scarily impractical.

NT

[Tim Watts]

For some reason, doing a Google Image search on "Moore's tube" with safesearch off is a really bad idea (glad I'm working from home today!)

I really can't figure out why!

[Huge]

There appear to be a number of pr0n "stars" whose surname is "Moore".

[Lobster]

Thanks Adam!

like a plan. So if I maintain the house CU as it is would I just fit standard MCBs in the garage CU? Would the house RCD still trip in preference to them?

That would be a really good idea actually; unfortunately the non-RCD side's already full though, and wouldn't be easily sorted. A new busbar, cut differently, would sort it; however it's quite an old CU and I don't rate my chances of getting hold of one! :(

Thanks David

[ARWadsworth]

> Sounds like a plan. So if I maintain the house CU as it is would I

Yes, just standard MCBs and no RCD in the garage (you will be using the house RCD). Of course what trips depends upon the type of fault! You would be in the same position as before but with a cheap CU not an old fusebox.

Whats the CU?

[Nick Odell]

It's the thing the wires come into and go out of again.

HTH

HAND etc etc :)

Nick

[ARWadsworth]

vbg

Have you been watching Airplane:-) - re hospital gag?