Extension leads

[Joshjosh]

Hi
So I've managed to convince a friend to let me use his garage as a workshop, only thing is it doesn't have power and is 50/60m down his garden. Largest tools I plan on getting are a single phase table saw (an old wadkin maybe) and a planer/thicknesser kity 636 or something similar size
Just wondering if running a decent extension cable from the house will work and give adequate power ?
Any advice would be greatly appreciated thanks
Josh

 

[Myfordman]

I think you will have to use a 16a or 32a Commando connector lead and 2.5mm flex making it not a standard extension lead but do able.

Ensure that the full length is unwound from the reel otherwise the coiled portion will likely overheat.

It is the starting current of these big machines that is high and if it causes the voltage to drop too low, the high current lasts for longer and can damage both motor and cable. Wire the commando socket at the house end via C32 breaker NOT a domestic B32 as the former is designed for motor loads.
Your mate should not be concerned that you will be using lots of his leccy just cos you have a beef cable. It is all about starting current.

 

[Joshjosh]

I think you will have to use a 16a or 32a Commando connector lead and 2.5mm flex making it not a standard extension lead but do able.

Ensure that the full length is unwound from the reel otherwise the coiled portion will likely overheat.

It is the starting current of these big machines that is high and if it causes the voltage to drop too low, the high current lasts for longer and can damage both motor and cable. Wire the commando socket at the house end via C32 breaker NOT a domestic B32 as the former is designed for motor loads.
Your mate should not be concerned that you will be using lots of his leccy just cos you have a beef cable. It is all about starting current.

Thanks I'm not too hot on electrics so trying to understand I figured getting a machine that doesn't exceed 13amps I'd be ok with a standard 13amp extension, would this work if I had machines with soft start? I need something I can roll out when I need it and pack away when I don't and that can plug into a standard house socket near the garden

 

[Joshjosh]

Would a newer saw like the Charnwood w629 be easier to supply?

 

[sunnybob]

Machine make does not come into it.
The longer the cable, the greater the resistance.
The greater the resistance, the higher amps.
A machine that will run all day on a 13 amp plug put straight into a wall socket, will blow that same circuit fuse every time if the lead a 100 metres long.
The first half second at startup can use as much as 10 times the running load.

Its possible even a 2.5 mm lead will still cause too much resistance if its 60 metres long. The load can be calculated by a professional electrician.
Also it would be very dangerous if you left an ordinary extension lead permanently in place laying across open ground. You would need to reel it up after every usage.

 

[hawkeyefxr]

I would not run flex for that length in a garden, to dangerous it could be hit with a spade of rake and kill someone, it will also degrade over time.
Use 4mm SWA (steel wired armoured cable), you may get away with 2.5mm but you will notice the light dim momentarily when you start your tools.
My run is 20 metres and i use 2.5mm and i used to get the lights dip slightly when i started my planer thicknesser but it was quite a big machine.
I run mine direct from the fuse board in 2.5 mm twin and earth to the outside wall, this goes into a sealed box and from there to the shed in SWA, it has been in for over ten years with no trouble

 

[bawdseymatt]

It's really worth trying to find out what the start up current of the machine is (I think sometimes called 'in-rush' current)
Might be worth pricing up the cost of the SWA cable and boxes as it's not as much as you probably think and certainly a much better way of doing (in my opinion at least) if possible.
Yes it means that you can't reel the power supply back in each night but the permanent solution will be better and safer.

 

[RobinBHM]

Years ago I had a garden workshop and made do with a cable clipped to the fence.

It ran from a 13a socket. It was ok, but the planer thicknesser often blew the fuse on start up.

That was about 30 metres.

I would a distance of 50 metres using extension cable would have too big a volt drop and you may get fuses blowing on start up.

 

[AJB Temple]

Both tools that you mentioned will have a high start up draw. The PT will produce waste by the bucketload and you will need some kind of chip/dust collection system for the good of your lungs, so you will need to run two machines and lighting most of the time. You have no chance whatsoever of making the workshop operate satisfactorily from a 13amp external socket and an extension lead for that length.

I would also be surprised if an electrician would pass 2.5mm armoured for Part P purposes. It would add value to your friends garage if you put in armoured and a small consumer unit in the garage. You can then put in 16 amp single circuit sockets and a 13amp ring. This will require you to dig a narrow trench from the consumer unit in the house to the workshop. I would suggest this is only worth it if you have a long term deal with your friend.

 

[Hot stuff]

Get the power put in properly as a thank you for the use of the garage. You'll both benefit from the convenience and the safety.

 

[Joshjosh]

Thanks for all the advise guys I really appreciate it, I can rule out the extension then. Problem with permanent wiring is that it's only a short term arrangement and he's thinking of knocking down the garage in a few years and building elsewhere
How about a small generator, would that work? Something that'd produce about 2 or 3 kw

 

[Terry - Somerset]

Even if your main machine can be run with a 13A supply you need to add one or two kw to cover extraction and lighting.

A separate generator with adequate capacity would not be a trivial expense - particularly when servicing and fuel are included. I suspect reliability would be materially worse than mains supply, and if run 8 hours 5 days a week may be at the end of it's effective service life after 3-5 years.

 

[AJB Temple]

Generators are also noisy. I suspect this solution would make you unpopular and shorten your short term arrangement.

 

[kevinlightfoot]

I have just finished building my new workshop at the bottom of my garden 40 metres away from the sub main my electrician insisted that 10mm cable be installed because of the voltage drop problem extension leads are not a very good solution.

 

[bugbear]

Some good info (and some rancour) in this thread:

swa-2-core-120-sq-mm-cost-for-800-m-t101750.html?hilit=%20current%20voltage%20drop

BugBear