Home Outdoor Studio Set up

[stmartin1991]

Basic question to see if what I wish to do is correct:

Client wants to build (or is building) and outside room (roughly 8m by 4m) to be used as a sound recording studio.

He wants power to it and has ran 10mm SWA from the house to the studio, ~7m underground direct and 10m clipped to wall and running in garage ceiling (open)

His current house is coming off of the mains in what looks like 10mm T+E (could be 16mm? hard to tell)



I plan the current load of the studio as follows:

1 x 20A sockets on 2.5mm twin and earth for the sound studio
supplying roughly 10 single sockets around the circumference of the room (total length 15m Radial) in conduit and garage boxes (minimal penetration of sound proofing)

1 x 20A sockets on 2.5 for the kitchen sockets - supplying a small fridge, extractor, and a couple of double sockets likely to be used for single plug in induction hob, kettle and microwave

1 x 6A feed for lighting, possibility of future external garden lighting off external light switch

1 x 16A feed for Air Conditioning unit

1 x 16A using for industrial plug for campervan hookup

Applying diversity it comes out at about 51.8A

I'm hoping that the 10mm SWA 3-Core is sufficient given diversity?

I intend to come from the supply mains 100A switch consumer side, through a proper 100A block with new 25mm+16mm tails to a new board (old board connected into block also as there is no way of getting the 10mm SWA to the board, plus the new load may be too much to run through existing consumer unit)

The new board will be in the garage ceiling (un insulated) as the client is very particular about where things are positioned and being neat and tidy

The first board in the attic will be a 100A main switch w/ SPD supplying:
1 x 63A - supplying studio (through 10mm SWA, tough decision as 50A may be too small for studio but too big for Current Carrying Capacity of the 10mm?)
and a spare way (likely to be 32A car charger in future)

On the studio side I plan to have a 63A main switch then the above RCBO breakers for each circuit

Does this seem acceptable?
Is 10mm big enough? he did plan on running 6mm and I proposed he ran 10mm instead
Do I need a separate earth rod at the studio end?
SWA outer sheath only needs to be earthed at studio end,

I work for a builder and have passed all my relevant City and guilds and have been working with electrics for the last 5 yrs doing minor works such as extensions, kitchen remodels etc as well as a couple of new builds. All my previous work has been tested by me (during install) but retested after completion by a registered NICEIC electrician (I am not yet self certified). This is the first time I have had to add a out building without going through the existing board so need a few pointers as to if what I plan is acceptable.

Any advice would be helpful, I have wired everything already and the client is getting close to wanting to buy the boards etc but I want to just check before he spends the money on RCBO's etc.

 

[Lucien Nunes]

From the fact that you have not identified any socket-outlets specifically for equipment racks, and from the dimensions I am inferring that it is a small studio with relatively un-demanding electrical specs. It's worth mentioning though that for really top-notch installations there may be a requirement for special earthing arrangements to minimise noise and interference into the audio circuits. For example, TN-C-S earthing might not be acceptable for noise reasons, even if it's OK safety-wise.

Equipment racks where fitted can produce in excess of 3.5mA leakage current due to the number of separate pieces of equipment running from a single feed, and therefore should not be connected using 13A plugs (16 or 32A is usual). High-integrity CPCs are also sometimes merited where the total leakage could exceed 10mA. TBH I would avoid having the entire studio electronics earthed by one 1.5mm² CPC in a 2.5mm² T+E 20A radial which is what it sounds like you are suggesting. Also, while the 20A circuit will almost certainly supply enough current for the gear when running but a B20 RCBO might not withstand the inrush of a number of monitor amps coming on at once.

Elsewhere, One 20A circuit sounds a bit skimpy for the kitchen load including an induction hob.