Lights and power in the workshop

[Pete.]

I have to re-wire the workshop because:

1. The sockets are randomly placed at random heights which must have suited the original owner but don't make any sense at all for my layout.
2. I'm fully re-boarding the workshop with insulation so I can get rid of the plastic surface mount boxes and replace them with flush mount metal sockets
3. I'm not entirelty happy with the way it's been done. For instance one half of the workshop has an armour coming from the CU though an underfloor duct into a junction box, with a single T&E coming out of that into a fused switch, which acts as an isolator for not only the lighting circuit but also seven double sockets on a radial circuit one of which has a further spur off it



So my workshop is essentially two timber garages end to end with a 6 foot gap that's been bridged to make one continuous workshop inside. There is a consumer unit in one end near the house serviced by an armour through a cable duct under the slab. The workshop is split into 2 sections with a roller shutter between them. One section holds all the equipment lathe, mill, grinders, gear hobbers etc, the other will be work benches, welding, storage etc.

I want to have 3 lighting circuits. One for minimal lighting so I can just light up the entire workshop if I pop in there to get something. I have the original twin mini-fluorescents for that because they will reflect off the silver foil roof insulation and spread the light. Then I want to light each half of the workshop separately so that if I have no machining work to do I can just light up the bench area. I have some LED 600x600 ceiling panels which will offer a more diffused light, but downwards only so they will be local lighting. I'll have to see what sort of coverage they offer

For power I want to put in two circuits feeding separate wall sockets in each section of workshop. I favour ring circuits for no other reason than I've never lived in a place that didn't have them. Is this still acceptable these days? If so I will put one ring circuit in the machine shop (fed from the above junction box, but not through that switch) to power all of my machines and another ring curcuit directly out of the CU in the welding/bench workshop with a load of wall sockets for power tools and charging station etc. I also want to put in a couple of 16a radial circuits for the compressor and welder.

 

[Gregb23]

I did all mine in radials as saved having to run an extra cable back in the trunking I used. Though I also did the rest of the house in radials so no rings for me here. Didn't check the price of the copper radial vs ring but was a little quicker and easier to run it all. In theory should also make it easier to fault find should the issue arise.

 

[gaz1]

id fit another cu unit in other part of shed and direct mains wire it over to it

 

[awemawson]

In a previous workshop I had the 240v single phase power circuits rigged to an eStop button & contactor by the entrance / exit. This proved very useful as pressing the button on leaving I KNEW that everything was powered down. It wasn't practical in my current workshop for various reasons and I regret not having it.

I opted for a double 13a socket every metre round the periphery which seemed like a grossly extravagent arrangement but has proved very handy. I split it into two ring mains (north & south) with a third ring for services such as the boiler, hand driers, and destratification fan. There is another radial circuit for computers, wifi hub, cameras etc.

The three phase distribution I handled as a completely separate set up as there are sub mains going out to four other buildings with individual isolation as well as an overall isolator of the 'throw the switch Igor' variety

 

[8ob]

I went for trunking, put the lot in one place and spur off that. Makes adding/moving points a lot easier.

 

[MetalMonkey]

Need a bit more information on the existing set up first.

How many ways do you have in the workshop consumer unit? What breaker sizes do you have available?
How is the workshop consumer unit supplied? Does it come from the house CU, what size breaker is it fed from? What size cable?
Is the SWA to the junction box fed from the workshop consumer unit? Again what size breaker, what size cable?

For lighting, unless there is a specific reason to have it fed from different circuits, I'd suggest one lighting circuit will be sufficient, and just have a three gang switch to control your different areas.
Do you need any outside lights? If so, stick them on a separate circuit.

For power, you could put in one ring, or a couple of radials. Depending on what is going in there, two rings are probably overkill, but no reason why you can’t.
Separate radials for each commando socket for welder/compressor etc.
Separate radial for any outside socket.

 

[addjunkie]

If the SWA is man enough for the proposed load, Id fit an isolator, then a new fusebox, and follow Metal Monkey suggestions.
If SWA and house end breaker not suitable Id start from scratch.

 

[Pete.]

I have a B32, two B16 and two B6 in the CU.

I won't be messing with the house wiring though I'm not averse to swapping out the CU in the workshop.

 

[MetalMonkey]

Really you do need to take into account what is feeding the consumer unit before you go altering or adding anything, but just looking at what you have available I'd go B32 for a single ring, B16 each for 16A sockets for compressor and welder, and one B6 for your internal lights, spare B6 if you want an external light.

 

[minimutly]

In a previous workshop I had the 240v single phase power circuits rigged to an eStop button & contactor by the entrance / exit. This proved very useful as pressing the button on leaving I KNEW that everything was powered down. It wasn't practical in my current workshop for various reasons and I regret not having it.

I opted for a double 13a socket every metre round the periphery which seemed like a grossly extravagent arrangement but has proved very handy. I split it into two ring mains (north & south) with a third ring for services such as the boiler, hand driers, and destratification fan. There is another radial circuit for computers, wifi hub, cameras etc.

The three phase distribution I handled as a completely separate set up as there are sub mains going out to four other buildings with individual isolation as well as an overall isolator of the 'throw the switch Igor' variety

Regs are one thing, but if the workshop is your own I see no reason not to put as many sockets on a circuit as suits the layout - one person can only use so many outlets at a time.
I like two lighting circuits though, if you don't have emergency lights. Nothing worse than fumbling your way out of a shop littered with stuff that could hurt you.

 

[MetalMonkey]

Regs are one thing, but if the workshop is your own I see no reason not to put as many sockets on a circuit as suits the layout - one person can only use so many outlets at a time.
I like two lighting circuits though, if you don't have emergency lights. Nothing worse than fumbling your way out of a shop littered with stuff that could hurt you.

Providing it is not likely to be overloaded there is no limit to the number of sockets on a ring, historically for anything serving under 100 square meters.

Two lighting circuits are fine, but will obviously only work in case one trips off due to overload/short, which I think would be fairly unlikely. Usually it is the RCD that trips off, and they would need to be on separate RCDs/RCBOs for you to get the benefit.

Again going back to the supply, I’d recommend either having the workshop supply fed from an RCBO, or if suitable, a time delay RCD with local RCD protection. Nothing more infuriating than tripping off the power and having to go back into the house to reset it. Especially if the better half was halfway through cooking or their favourite TV show…

 

[minimutly]

Providing it is not likely to be overloaded there is no limit to the number of sockets on a ring, historically for anything serving under 100 square meters.

Two lighting circuits are fine, but will obviously only work in case one trips off due to overload/short, which I think would be fairly unlikely. Usually it is the RCD that trips off, and they would need to be on separate RCDs/RCBOs for you to get the benefit.

Again going back to the supply, I’d recommend either having the workshop supply fed from an RCBO, or if suitable, a time delay RCD with local RCD protection. Nothing more infuriating than tripping off the power and having to go back into the house to reset it. Especially if the better half was halfway through cooking or their favourite TV show…

Agree with all that, except maybe the bit about lighting circuits tripping - a faulty fitting would be quite possible, mine went out this week, hence having a purge on changing out old fluorescents...

 

[MattF]

Nothing worse than fumbling your way out of a shop littered with stuff that could hurt you.

The good old unexpected power cut scenario.

Wonder how many of us have been in our workshop, at some point, thinking "Dare I move", whilst mentally envisaging the workshop layout.

 

[voipio]

The good old unexpected power cut scenario.

Wonder how many of us have been in our workshop, at some point, thinking "Dare I move", whilst mentally envisaging the workshop layout.

I've taken to always carrying a small torch in my pocket. It's only a little single AAA-cell LED jobby, but quite bright, and typically gets used several times a day, mostly looking into boxes, and under-table spaces and cupboards for stuff. It's also useful in helping to read small print on stuff. We do occasionally get power cuts, though most have been during daylight hours.

 

[MattF]

though most have been during daylight hours.

That never helps, with me. No windows in the workshop.

 

[awemawson]

The good old unexpected power cut scenario.

Wonder how many of us have been in our workshop, at some point, thinking "Dare I move", whilst mentally envisaging the workshop layout.

I got hold of some 'unmaintained EXIT' signs that are battery maintained in a power cut. They have proved their worth more than once. Although I only have one main entrance / exit I have a welding shop off the main workshop separated by double leaf fire doors so one is mounted over them in the welding side.

 

[Pete.]

The good old unexpected power cut scenario.

Wonder how many of us have been in our workshop, at some point, thinking "Dare I move", whilst mentally envisaging the workshop layout.

Had that at my old workshop I ended up putting a magnetic torch on the wall next to the door.

This time I have some battery backup drivers for the LED panels.

 

[gaz1]

Had that at my old workshop I ended up putting a magnetic torch on the wall next to the door.

This time I have some battery backup drivers for the LED panels.

backup battery lights come in handy more so with the new led tech

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[brightspark]

if your so worried about powercuts just fir a couple of none maintained emergency lights as in above post . they cost peanuts i wouldnt bother as never had a powercut in 40 years during the night .even though the garage is like a tip i can walk through it blindfolded . if your fitting ringmains etc make sure the supply in is no less than 6.0mm either on a 32 amp or preferably a 42 amp mcb any less and its pointless having rings

 

[Pete.]

if your so worried about powercuts just fir a couple of none maintained emergency lights as in above post . they cost peanuts i wouldnt bother as never had a powercut in 40 years during the night .even though the garage is like a tip i can walk through it blindfolded . if your fitting ringmains etc make sure the supply in is no less than 6.0mm either on a 32 amp or preferably a 42 amp mcb any less and its pointless having rings

If I'm not running a ring main then whayt's the best layout for a radial. I don't mind buying extra wire I just don't know how to set it out.