running on extensions

[pike]

i'm using about 40 meters of a 50m extension cable temporarily, to reach my shed until I sort out permanent power.

I've read the max ratings on it and based on my understanding I can get away probably comfortably with a power tool up to about 1500w with probably 500 or more to spare (based on the cable being mostly unwound).

I decided to see if my 2000 watt table saw would work and it couldnt start. I half expected that.

My question is, is it dangerous to try to run anything other than light power tools on the extension? Or will it simply start or not start?

Thanks.
turnpike

 

[kasandrich]

It would be better to unwind all of the spare lead and leave the spare cable laid out on the floor.

The problem is that to form an electric heater, you would form a coil, which is what you have on your extension lead, by rolling it out you remove the coil and remove the heater.

 

[9fingers]

It is not an ideal way to run tools but you know that already!

If a tool will start up OK then I would carry on using it. Generally tools are not used for long periods of time. I would not run things like heating which are longer term high power loads.
You probably have a light on all the time and that is both fine and a useful indicator of the voltage drop. If the light is continually dim then the power is going somewhere and that is as heat into the cable. Check that the cable, especially the coiled part is no more than gently warm. If the cable itself is limp and floppy then you are overdoing it**.

Make sure also that the socket in the house in in good condition and the fuse clips in the plug are clean and tight. If the plugs pins are warming up, STOP and sort it out. Dont use a rubber plug, the vapour given off by the rubber causes an insulating black layer to build up on the fuse and this will cause trouble.


In essence proceed with care and keep an eye on what you are doing and pay attention to the telltale signs.

Make getting a proper supply a high priority!

hth

Bob

** Edit. Some cable is quite flexible to begin with. Be concerned if the cable becomes more limp/floppy than before you started drawing power.

 

[OLD]

Roughly watts equals volts times amps so you have a max of 8 amps but the saw motor draws more on start up, it pulls the volts down and no start up .Why not run some 2.5 twin and earth as a better temp. solution with a plug in rcd device at the feed plug end for safety.

 

[RogerS]

Bob beat me to it.

Only slight caveat is regarding 'floppy' cables as some extension cables (usually called Arctic or similar) are by nature very floppy to begin with.

I'd also add to check the top of the plug to see if that is warming up since that will indicate worn - ie high resistance - connection for the fuse.

Please remember to pull the plug out before you test the pins for warmth. :wink:

Add if you do run an SWA cable then go for at least 6mm and ideally 10mm - DAMHIKT. I installed only a 4mm but that was when it was going to be an outbuilding used as a gym. Somehow a large number of woodworking machines found their way in. It is only because my incoming voltage is 250v that I can get away with starting up the Sedgwick.

Roger

 

[pike]

Thanks all.

It is an arctic cable. I will unwind it fully in future. My problem is I'm not in the position to get the proper supply in yet because of other works around where it would have to exit the house.

I guess I knew the answer really. Going to have to get the power sorted before I buy any new toys :-|

kasandrich: good point about the coil heater, always worth being reminded of that.

Bob: That's what I wanted to know. I think I understand where the risks are better now. Overheating wiring is the likely problem.

OLD: That sounds like a good option. If I can get the permanent feed in I will do it but right now it might be arkward due to other building works I need done where the power would be exiting the house. However, is there any point using an RCD device if the consumer unit has them? I thought I didn't need additional RCD now that I've got a modern fuse box.

Please remember to pull the plug out before you test the pins for warmth.

will do Roger. i hadn't intended to make myself an entry in the darwin awards

 

[Dibs-h]

i'm using about 40 meters of a 50m extension cable temporarily, to reach my shed until I sort out permanent power.

I've read the max ratings on it and based on my understanding I can get away probably comfortably with a power tool up to about 1500w with probably 500 or more to spare (based on the cable being mostly unwound).

I decided to see if my 2000 watt table saw would work and it couldnt start. I half expected that.

My question is, is it dangerous to try to run anything other than light power tools on the extension? Or will it simply start or not start?

Thanks.
turnpike

I'm in a similar position. I'm using a 13A rated extension - 25m long and fully unwound. I generally try to ensure the load is no more than 2KW.

Although in a few days I will have to fire up the P\T and it will be interesting to see if that runs. Although that has run in the house before on a 13a plug.

I always fully unwind extensions (and ensure the cable doesn't end up in a coil on the floor) after having seen someone elses catch fire.

 

[Racers]

Hi,
Don't forget that your safety earth connection is also on the other end of the cable and will have a higher resistance so you won't be as safe. Get it sorted out properly, quickly would be my advice.

Pete

 

[pike]

I've been looking at getting myself a bandsaw (1500w) but I'd need my Trend T30 going as well. 1500w saw with a 100w vacuum would be too much I think, unless I don't understand how the trend's take off feature works.

 

[pike]

Pete, yeah getting a proper supply in soon is going up my priority list.

I'd like to lay the armored core myself (then get the leccy to do the rest) but I'm not clear how to lay it to supply two sheds (one small one built, the other workshop some way off).

Can both sheds run off the same 6 or 10mm swa? Do I just put a join in or something?

 

[9fingers]

Pete, yeah getting a proper supply in soon is going up my priority list.

I'd like to lay the armored core myself (then get the leccy to do the rest) but I'm not clear how to lay it to supply two sheds (one small one built, the other workshop some way off).

Can both sheds run off the same 6 or 10mm swa? Do I just put a join in or something?

If the layout permits, bring the cable into the first building and then daisy chain into the other. Otherwise, two separate cables heading to each building.

bob

 

[kasandrich]

Don't forget you can always run 2 extension leads (the heavier the cable the better), run light and general bits on one and save the heavey duty one for the saw.

 

[pike]

thanks kasandrach. I don't like leaving the extension out all the time and it's a pain already winding one i'm not going to use the saw again. I've just picked up a lower power more portable one which I wanted anyway.

so now how best to safely use the extension.. and that it really isn't going to do for too long.

for the proper supply i am thinking i will lay this and let the leccy do the rest:

* 10mm 3-core SWA running the whole 40/50m.
* 60 mm waste pipe with draw strings
* pipe bends up under shed and up just outside house

I'll redirect it or link to the proper workshed when its built.

The swa will go right to the shed consumer unit.

At the house end, can I bring the swa out of the ground outside against an external wall and use a weatherproof adaptable box where i want to join it to 10mm twin and earth coming from inside?

thanks.

 

[wobblycogs]

Not sure I'd run the cable in drain pipe. I would have thought you would have a right job pulling 10mm SWA through it over that distance anyway. What I would do is: dig a trench 600mm deep, lay the cable, cover with sand, lay marker tape and then back fill.

Most plastic consumer units don't support termination of SWA cables so you might need a metal box next to it to terminate in the shed but I imagine your sparks will do that if needed.

 

[pike]

cheers. yeah i might get a metal clad consumer unit so I dont need a separate adaptable box.

regarding not using drain pipe, it would be so I could put other wires up in future. I'd hate to realise I'd forgotten something (e.g. if i decided to run one cable per shed or add security) and have to dig another 40 metre long trench.

point taken about how arkward it might be to fit in the pipe though. (memories of laying mdpe!) I guess 100mm will be better.

 

[RogerS]

......where i want to join it to 10mm twin and earth coming from inside?

thanks.

What is this feeding at the moment and where does it come from? Your consumer unit?

Agree re trenching. You wouldn't be able to pull 10mm cable round a rightangle bend anyway! But good idea to lay the 60mm pipe with draw strings. Why not run an ethernet cable down it, a telephone cable and for good measure a run of 15mm Hep2o plastic water pipe? You never know what the future may hold.

 

[pike]

Roger, it's not there yet. When I had a new consumer unit put in it I had a 40/60 amp breaker (cant remember which right now) left for this purpose.

As I understand I'd have to run 10mm twin and earth from the front of the house where the unit is, to the back of the house. Out through the wall to a weatherproof adaptable box where the swa is.

I've also read this afternoon that I might need an extra earth wire running along with the twin and earth.

I want this supply to feed my power tools, a bandsaw, table saw, lightning and heating.. the usual. For now It should just let me safely run those things one at a time in the short term shed.

If I put all those other services in which you mention my other half would think I was moving out for good! ;-)

 

[9fingers]

Well worth thinking about those other services whilst you are at it.

Water is not essential but the pipe only costs about 50p per metre

Having some general purpose low voltage wires can be very handy.
You should be able to pick up some multicore cable on ebay fairly cheaply.

For example, I have phone, front door bell and intercom extended to the workshop as well as interlinked flood light control so when I leave the workshop after dark, both the local flood and the one on the house come on and vice versa and then go off once I have arrived.
There are extra uncommitted wires for alarms etc.
Cat 5 networking could be useful but I use Homeplug signalling to get the interweb into the workshop.

Bob

 

[jlawrence]

I need to get around to re-running the power to my shop at some point. At the same time I'll be running a couple of cat 5 cables as well so that they can be used for whatever I need (phones, t'internet, doorbell etc etc etc). It doesn't cost much and might as well be put in at the same time as the swa.

 

[RogerS]

Roger, it's not there yet. When I had a new consumer unit put in it I had a 40/60 amp breaker (cant remember which right now) left for this purpose.

As I understand I'd have to run 10mm twin and earth from the front of the house where the unit is, to the back of the house. Out through the wall to a weatherproof adaptable box where the swa is.

I've also read this afternoon that I might need an extra earth wire running along with the twin and earth.

I want this supply to feed my power tools, a bandsaw, table saw, lightning and heating.. the usual. For now It should just let me safely run those things one at a time in the short term shed.

If I put all those other services in which you mention my other half would think I was moving out for good! ;-)

If it were me I'd get my sparky in to tell me where to terminate the wire etc.