Electricity supply...

[MR H 91]

I'm in need of more power in my garage to supply my new Jet JPT-310 and a dust/chip extractor that I haven't purchased yet which will of course be running along with the P/T. I'm no electrician, hence the thread but I know the wire currently installed in the garage from the consumer unit in my house is currently 2.5mm twin and earth.

Of course I'll never be using a table saw, planer/thicknesser and router at the same time, but I will be using the dust extractor plus one of these tools at the same time. I will of course have a couple of lights on too (4 fluorescent tubes in total) and will require sockets for power tools, but wont require them to be powered at the same time as my machinery.

My question is, how does one work out the required amps needed to power them both at the same time? I have a close family member who is an electrician and he will install the wires, fuse board and 16amp socket for me so I'm sure he will know what to do but just want to be sure in my own mind before I go and spend more money on tools that I may not even be able to power up. Am I right when I say, the power cable will come directly from the consumer unit and then split into smaller amp fuses within the workshop?

I hope this makes sense and sorry for the long winded question.

Thank you

 

[Phil Pascoe]

I have a close family member who is an electrician and he will install the wires, fuse board and 16amp socket for me so I'm sure he will know what to do ...

I think you answered your own question, there.

 

[paulm]

Had my garage/workshop supply upgraded a few years ago. The electrician ran a new swa cable from the main house consumer unit, non-RCD protected side, to a new smaller consumer unit with it's own RCD in the garage.

The garage consumer unit had a number of circuit breakers in it to cover the lighting, power sockets, and one dedicated to the 16 amp power circuit.

The swa cable was substantial in cross section, but that partly depends on the length of run and therefore voltage drop over that length, as well as power requirements at the garage end.

Don't forget that you may want to have a heater of some sort running in the garage at the same time as the planer thicknesser and chip collector, and some of those can be 3kw themselves ! The cost of the supply cable is pretty modest in itself so absolutely no point being too conservative with the sizing of it, if in doubt suggest to the electrician that you over specify it to allow for unforeseen future needs, as most of the cost will be from labour, new garage consumer unit etc.

 

[RobinBHM]

Basically you need a sub main, ie a thick cable from house CU to a new consumer unit in garage. In garage split up in same way as house.

Garage consumer units only have 1 x 6amp and 1 x 32amp usually, so maybe you will want to buy a house type unit with a few ways.

The complication with machines like planer thicknessers and table saws is the huge current draw when switched on. A C rated mcb has a curve that aloys a bigger initial surge which helps but it will need a fair size breaker. The cable size will need to have a bigger rating than the breaker that protects it.

I doubt if the current draw of the 2 machines when running will very high, but do include for extractor and heater load on top. If the cable run is short it makes sense to put in a big swa cable to cope, although terminatjng big swa cables is fun! and they dont go around bends well, so allow for gentle bends when routing. The saw and planer can be run off radials with suitable mcb for each.

 

[sunnybob]

Is your 2.5 cable a single wire from a consumer unit? or is it a part of the household socket ring?
A single wire will not take as much as a ring circuit.

But I have a single wire into my garage adjoining the house so the run is barely 3 metres. i have a 3 mcb unit in the garage, a lighting circuit, a seperate line for our pumped water pump, and 4 double sockets on the last mcb.

Technically, I am well over loaded. But as its only ever me, and I would never run more than two machines at the same time, I never get close to maximum load.
According to the axminster site your machine uses 3.5 kwatt. Thats barely more than a fast electric kettle, and you could easily run that, a dust extractor, and a couple lights from your existing circuit (unless youre on a 30 metre extension lead of course).

 

[Mike-W]

Mr H 91,
I have much the same set-up as you are talking about, my workshop has a 4 way (wire) fuse box that i run lights (5amp), ring main (30 amps) and euro sockets (15 amp), the feeder I installed from what i recall is 4 mm T&E, that is connected to my main fuse box on a 32 amp trip which is also on the Earth leakage side of the fuse box, this has worked well for me for many years, i can run the PT and chip extractor at the same time without any problem although occasionally the 15 amp wire fuse on the Euro socket will blow as the fuse rating is on the limit of the start up current of the PT.
The run from the fuse box is approximately 30 metres and as my outside workshop is right up against my bungalow the cable is just about all within the bungalow, hence normal T&E.
The key consideration for you i think is do you have a spare outlet from your consumer unit (fuse box) with a capacity for something like a 32amp trip, cabling size and type is down to current IEE regs, i think wire fuse boxes are now not permitted on new installations, so you will need to agree the design with someone qualified in this area. My advice came from my dad who was a Sparks, i till have his AEEU 'Green Book' Electricians guide to Good Electrical Practice 1995.

 

[Bodgers]

Low sensitivity RCD might be worth it on one of the circuits for the Jet planer. I think it is the Jet 260 that needs 16 amp as well, but pretty much only because of the initial switch on draw.



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[MR H 91]

Thanks to everyone that answered, you've all cleared things up and now get what needs to be done.

 

[tomlt]

I have a Jet 260, great planer but needs some juice on start-up when cold in the winter. Mine was on a 16amp c-curve and would pop that 3-4 times before starting (running 4-5secs each time). For the 310 you'll want to go bigger? Id recommend a 32a socket and the either a 20A or 32a breaker, c or d curve if you can get one. Keep this independent from your other power feeds for the dust extractoion etc.

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[richy3333]

Speaking as a sparky, some of what has been said isn't quite correct and is unreliable. Find an electrician that is qualified (not a Domestic Installer - I'm assuming you are in England) and ask them to do the calculations for you. They need to look at your main incoming supply and then what the set up is in the house to take into account what might be required in the workshop. Have a list of what will be used in the workshop rated in Watts and the sparky can look at demand and diversity. Think about future purchases etc. They can then calculate the required cable size to supply the workshop and having taken account of voltage drop etc and installation type recommend a suitable cable and size. This feed is a sub board from your supply/main CU it isn't a sub main. If they are buying from a proper wholesaler and not a shed then there's absolutely no need for a 'garage board'. They can just get you a CU and make up the insides as required. The CU will have to be metal clad now in a domestic environment. BTW if they don't certify the work, don't pay!

Hope that helps.

 

[cammy9r]

https://www.tlc-direct.co.uk/Technical/ ... eDrop.html This link might help you find the correct size of cable to feed the garage with. 2.5mm t&e at best is rated to ~26 amps. I added up what I thought I would have on at once, saw 2000w, extractor 2000w, heater 2000w and maybe my compressor was left on and it kicks in...another 2500w. Total 8500w, the above link said I would need 10mm for a 50m run (from CU to CU).

 

[kevinlightfoot]

Just had my workshop sorted by my sparky who is very good.New sub main fitted with a feed of 10mm cable 2 radial circuits with 4mm cable. Ring main of 10 double gang sockets and lighting 5 double fluorescent tube fittings.The radial circuits are fitted with c20 mcb,s to cover the starting current of the table saw and planer thicknesser.Get it over engineered at the start and you will probably not have to worry about it again and you can get on with your woodworking.Happy Boxing Day.