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g-money
7th September 2011, 08:40 AM
Morning All,
Just after some opinions on my plan to get power to my shed.
Digging a trench to run some cable in conduit is not really an option for me; I would then need to demolish a good amount of some brick stairs :no:. So instead I was planning on using an extension cord on a reel. When I want to go down to the shed I would just grab the end and walk down with it.
I based the idea on caravans, I plan to put a 15A inlet on the shed that would then be connected to an RCD which would be connected to 4x GPO’s and 2x fluro lights. The other end of the extension would be plugged into a dedicated outdoor 15A plug wired back to the switchboard on its own circuit. This point and the shed would not be used at the same time. In the shed the 15A tools will also not be used with anything else running (apart from lights maybe)
Not many heavy duty tools will be operated in the shed, the biggest would be a 15A dewalt CMS.

I’ve been doing some searching and it seems most people are against the extension idea. I’m not too sure if it really is that much of an issue considering it will still be on its own circuit and the cord will also be 2.5mm. And when I go back in the house I would bring the extension with me, not leaving it outside on the ground. Lead would be 15A HD Construction lead, about 30 meters.

Cheers,
Gareth.

Boringgeoff
7th September 2011, 09:41 AM
Hi Gareth,
that option would be ok in the short term, I've got a similar set up to get power down to the saw bench in my (fire) wood shed. But I only use that once or twice a year.
How many years do you intend using this arrangement and how frequently?
In the long term I could see this becoming an absolute pain in the butt.
How about posting some photos or a diagram of your situation, it's only 30 metres and you might be surprised at the amount of expertese out here.
Regards,
Geoff.

BobL
7th September 2011, 10:22 AM
I agree with Geoff, post a photo of your situation. For example it is sometimes possible to place conduit down the sides of concrete stairs or go overhead (it might still not be legal but it will be safer).

As a kid in the 1960's I used to drag a cable down to the shed. Ones intentions are of course initially safety focussed but I began to forget and would often leave it for weeks without dragging it back to the house. After a couple of years or so of weekend warrior use the cable had become so twisted and damaged I had to throw it away. Mum dropping a pot plant on it where it crossed a wooden footpath did not help. My eventual solution was to suspend a new cable on wire run between the house and the shed roofs. My uncle who worked for the SEC at the time gave it the once over to make sure it was not going to cause a problem.

Admittedly the extension cables of today are better than those from the 1960s but one problem with your solution is you are placing two extra power points in line with every appliance and this places extra resistance in the line. This means the voltage drops and so appliances will pull more current. Initially this will be small but will increase as the powerpoints and line age.

Legally of course if things go pear shaped then it will be hard to defend. You won't be able to use the caravan defence because a shed is not caravan.

g-money
7th September 2011, 10:26 AM
Thanks Geoff,

How many years i put up with it depends on whether i ever tackle the task of getting past those stairs! I do plan to spend quite alot of time in the shed so i think you be right, wont be long for that cord gets pretty annoying to have to use.

I've posted up some pictures that i had on my phone. You can get a good idea about the stairs form one of them. They wrap around the bottom of the house and continue. So any conduit would somehoe need to get underneath at the bottom or at teh top and then run alongside. The shed is strait down 30m to the bottom of the yard.

Cheers,

BobL
7th September 2011, 10:46 AM
Its a bit hard to see what is going on in your photo as it is so small but I would consider putting a beam at 2.4m high over the stairs and and a post at the base of the stairs and then run the cable along the beam and down the post. If you put it all inside conduit it should be safe.

g-money
7th September 2011, 10:55 AM
one problem with your solution is you are placing two extra power points in line with every appliance and this places extra resistance in the line. This means the voltage drops and so appliances will pull more current. Initially this will be small but will increase as the powerpoints and line age..

Thanks for the reply Bob, i'll get some better photos to post up.

In regards to the voltage drop, this would be an issue regardless of whether i use an extention cord or not i assume? Is there a way to get around this? I;ve heard this can damage the power tools.

NCArcher
7th September 2011, 11:27 AM
Voltage drop is overcome by using larger cable. Give your local sparky a call. He will be able to advise you on the best route to run the cable as well as determine what size cable you need. Installing it in conduit on the surface and using a catenary wire are both valid and legal options. Cable can be run through the roof to the closest point to the shed and then via overhead, suspended on a catenary, to an anchor point on the shed.

g-money
7th September 2011, 12:08 PM
Might have to bight the bullet and dig up some stairs.Perhaps i can run conduit over one of thestairs and brick over that. The other half will not like suspended wire running down to the shed. Already doesnt like the shed now right in the middle of her view from the windows:)

I'm not experienced but i think 2.5mm cable over 30m drawing 15amp only has a voltage drop of about 2V. So may not really be an issue. Could always upgrade to 4mm cable, But i already have a 100m roll of 2.5 so would like to try and use that up if going the hardwired route!

BobR
7th September 2011, 01:13 PM
Whilst I can't get anything from your photo, you still might be able to dig under the stairs. There are tools available to dig tunnels under just about anything. Have seen the gas authority dig right under a road for one small pipe. See if you can hire something.

Skew ChiDAMN!!
7th September 2011, 01:31 PM
One trick, that depends heavily on the sub-soil type - and whether you have adequate drainage - is to get a length of electrical conduit slightly longer than your stairs are wide.

Drive it horizontally into the soil under the stairs, then slip a garden hose inside... and turn it on. Keep wiggling and twisting the conduit until you've worked it into the soil for as much of it's length as you can. (A pair of vice-grips clipped on the free end as a handle can make life far easier, too!)

Then you can dig a trench down on t'other side of the stairs to locate the far end of the conduit.

It can be messy, but it can also save a lot of time and expense when conditions are right. :)

Sadly, it can also be frustrating as all hell when you've worked it 3/4 of it's length in only to have it stop dead... because some mongrel brickie threw building rubble underneath the stairs. :sigh:

NCArcher
7th September 2011, 03:39 PM
I'm not experienced but i think 2.5mm cable over 30m drawing 15amp only has a voltage drop of about 2V. So may not really be an issue.
Actually it's just under 8V. (7.965V)

g-money
7th September 2011, 04:27 PM
Actually it's just under 8V. (7.965V)

Well, i was way off then!

That would still be within the 'acceptable' 5% range then i guess. For now until it deteriates. It should atleast do until i can work out and afford to have a 4mm line run strait from the mains to the shed. I suppose you can test with a multimetre to check if the drop is getting worse. How much of a risk would this actually pose to the tools being used? Only one of them is 15A it only really gets occational use.

Might also try the conduit and hose suggestion, thanks for that :)

Thanks for all the great help so far guys. Really looking forward to getting this shed finished. Have only put down the floor so far.

joe greiner
7th September 2011, 09:36 PM
Have a more detailed chat with your sparky. In the States, direct burial is legal, with proper grade of cable, depth, and junction boxes. Might also be advisable to place a metallic warning tape above it but underground.

Extension cords get very old very fast, especially with outdoor plugs.

Cheers,
Joe

wun4us
12th September 2011, 12:06 AM
In these days of rising electricity costs, there is always the option of a generator:rolleyes:

I frequently use a generator when out at my mate's farm, particularly for welding, and have used power tools easily. Have been using generators for years with the caravan, sometimes drawing up to 30 amps with 3 appliances on at the same time.

Just a thought

Grandad-5
12th September 2011, 11:39 AM
I have had a couple of past experiences running high drain tools on extension leads that may or may not give you some insight.
The first was an existing wired shed we had on 20 acres a while back. It was already wired for power when we bought it. For the entire time we were there we had annoying hiccups in that shed. If my 15 CFM compressor tried to start up at the same time as my TS was running, it would cycle badly. Try to start, stop, try again and stop etc. I'd have to quickly turn my TS off until it finished. I bought a new Gasless mig and it was great for very fine small tacks which is what I bought it for but it was impossible to actually run a continuous bead. I just put it down to my inexperience with mig and used my stick welder.
Just before we sold the property I had to dig a small drainage channel and uncovered the supply line. It was 2.5mm extension cord in conduit just 3" below ground. Total run was about 20 mtrs.
Most of my machinery has been in storage since we sold but I have concerns about what damage may have occurred during our time there. In particular, my compressor. It will be the first item to go get checked out.
That same gasless mig works just fine in my new shed with proper wiring.

The second instance was when I was building. I had a tradesman trailer with the same compressor mounted to it. I wanted the longest possible run from a power point to my nail gun. I spoke to a friendly sparky and he consulted a fairly extensive looking chart for me and calculated what the longest run of extension cord I could run on a worse case scenario before experiencing significant power drop. From memory it was around the 25 to 30 mtr mark. I then hardwired that length of lead into the trailer and bought enough air line to go the rest of the distance. Worked a treat because I got someone involved who understood these things and followed his guidelines.

So, two experiences with long runs of extension lead. One good, one bad.

ETA: Just remembered something else. That same sparky told me to never run the trailer compressor with the lead coiled up if I could park near a power point. Too much heat build up, which I had had previous experience with in my first mentor's cabinet shop. A coiled extension lead running a shaper set fire to a pile of sawdust it was laying under. We caught it in time but could have been nasty.

Robson Valley
17th September 2011, 01:36 PM
I made up my own 20m x 12ga cord. Work in the garden with new fences, posts and the like. 15A draw is not a problem as it was before with the usual skinny cords.
I don't advocate this as any sort of a long term fix. . . . but for anything I need to do outside the house, I can't complain at all.

pjt
19th September 2011, 01:08 AM
Just as an extension on what grandad said...if you roll or lay out (on the ground) an extension cord in a figure eight it doesn't heat up the same as if the lead is rolled up in a continuous loop, the induced currents aren't induced in the figure 8 pattern, I seem to recall that from an induction somewhere.....


Pete

Robson Valley
19th September 2011, 02:23 AM
pjt: some would call that a "buck & boost" effect in AC. A single coil would develop quite a mag field in each half cycle which collapses going through zero to build one in the opposite direction.

My experience is that I commonly need most of the length in my homemade line!
My guess was that the wire size would reduce the inherent I^2R power loss. Of course, the cord has a black skin so any mag field heating would be sort of disguised, anyway.

Grandad-5
19th September 2011, 10:23 AM
...if you roll or lay out (on the ground) an extension cord in a figure eight it doesn't heat up the same as if the lead is rolled up in a continuous loop, the induced currents aren't induced in the figure 8 pattern, I seem to recall that from an induction somewhere.....Pete

This place is amazing. I swear it's true. Not one day has gone by since I joined this forum that I haven't learnt something new.
Cheers
Jim

Rhys_holland
19th September 2011, 06:35 PM
as a sparky i highly recommend you call a sparky and get it done properly the volt drop on the 30 meter extension lead is 8 v you are allowed 11 volts but you also get your cable being derated for being in the sun or being underground + there is the length of cable between the extension lead and the socket outlet and the socket outlet and the tool i would suggest a minimum of 4mm and if it was for my shed i would be doing it in 10 mm but 6mm would suffice (just)

pjt
19th September 2011, 08:38 PM
This place is amazing. I swear it's true. Not one day has gone by since I joined this forum that I haven't learnt something new.
Cheers
Jim

I agree Jim, there's a forum for most things here and then there's the Renovate forum as well, ah so many forums so little time.....:p

Pete

dtmiskin
26th September 2011, 12:26 AM
Have a more detailed chat with your sparky. In the States, direct burial is legal, with proper grade of cable, depth, and junction boxes. Might also be advisable to place a metallic warning tape above it but underground.

Extension cords get very old very fast, especially with outdoor plugs.

Cheers,
Joe
I have just installed power to my shed if i can do it any one can with time and a bit of reading and looking on youtube. I followed the recognised 17 edition regs for the uk well most of it:D From my socket closest to the shed i used an RCD spur this protects cable to shed. In the shed i used a garage unit which has a 6amp light trip and a 16 socket trip with an RCD. Plan your route secure to a good wall(not a fence= rot or blown down) if you dig a trench sand in the bottom then tiles above the cable i used pea shingle and on top of this i placed warning tape and back filled. Connect all the shed up 1st, then back to your spur unit connect SWA to the unit allowing plenty of flex to connect. Turn off the mains connect your supply to spur job done:URemeber electric is worst than a snake you cant see the dam thing. Get a lecky to check out your work or help.

vk4
26th September 2011, 12:45 PM
I have a small shed(3x3mt garden shed , in which I have my workshop, it was the radio shack until the Miss's let me put them in the house,.

I have a heavy duty 15mt ext lead with 1.5mm wire , zippy tied to a s/steel cable at roof height , this supplies power to the shed, it has been a temporary fitting for 3 1/2 years.

Going by what I see here I will look at replacing it with at least 2.5mm buried in conduit and hard wire it in , My largest drain is the Lathe at 750watts.

With regard to getting power down to your shed , yes we need to see a better Picture of the house &land, I take it that the shed is to the right of the Picture??

If so I would run the conduit under the steps ( yes dig 1 up ) then to the shed, from what I can remember from when I sold extension leads the max run for 1.5mm sq wire is 30Mt at 2400watts MAX, I would think on that basis your 2.5mm Sq wire would be close to a minimum depending on your power requirements. You could always run 2 cables down IE: 2 circuits , 1 for the heavier tools and the second for lighter tools and lighting.

This is just a suggestion , as it would allow you to use the cable you already have , and spread the load , .


Jeff
vk4

Grandad-5
26th September 2011, 05:38 PM
I have a small shed(3x3mt garden shed , in which I have my workshop,..........

Hi Jeff,
Any chance of some pics of the layout of your shed?
I'm most interested as I happen to have a storage shed in my backyard of that size.
Would be good to see.
Over in the shed thread maybe so we don't hijack this one?

Cheers
Jim

joe greiner
26th September 2011, 09:29 PM
Just as an extension on what grandad said...if you roll or lay out (on the ground) an extension cord in a figure eight it doesn't heat up the same as if the lead is rolled up in a continuous loop, the induced currents aren't induced in the figure 8 pattern, I seem to recall that from an induction somewhere.....


Pete
Another advantage of the figure-eight coiling is to reduce kinks in the extension cord. When coiled in hand, the figure-eight is accomplished by alternately flipping the direction of wrap, in effect folding the figure-eight. Discussion here: http://www.woodworkforums.com/f18/rolling-up-electrical-leads-89406/

Cheers,
Joe

hunter2003
8th October 2011, 08:19 PM
Gareth,

I am just at the point of refitting an old shed. Unsure what the cost would be with the cable run, but a sparky quoted me around $350-$450 to install a new power board in the shed with light run, 10a run, and a 15a run. The correct cable to run from the house to the shed board is 6mm at least. I am lucky enough this is already in place. It is an overhead run from just below the guttering to the apex of the shed. Doesn't get in the way at all. You may want to look at getting a sparky in to do a quote for you. By the time you buy everything from Bunny's or other hardware, it may only cost you $200 difference. For the extra expense, you will be covered by your insurance company, and you will be ensured everything is going to work as it should.

I am a big proponent of DIY but work on the principle, if I can't see it when it leaks, then I don't play with it.

I agree with others that the extension cord idea is not a good one. Short term one offs, yes, but as a planned long term fix, no.

Hope this helps,

Kind regards,

h2k3

BobL
8th October 2011, 09:10 PM
Gareth,

I am just at the point of refitting an old shed. Unsure what the cost would be with the cable run, but a sparky quoted me around $350-$450 to install a new power board in the shed with light run, 10a run, and a 15a run.

That is very cheap. When I asked one WA sparky the same question he said ~ $500 but when I asked for a written quote it came to ~$800. Maybe it's the difference between WA and Vic at the moment.

Grandad-5
8th October 2011, 09:26 PM
That is very cheap. When I asked one WA sparky the same question he said ~ $500 but when I asked for a written quote it came to ~$800. Maybe it's the difference between WA and Vic at the moment.

Or...maybe the difference between two sparkys.
One that has plenty of work on at present, and one that doesn't?
Just a thought.
Cheers
Jim

BobL
8th October 2011, 09:39 PM
Or...maybe the difference between two sparkys.
One that has plenty of work on at present, and one that doesn't?
Just a thought.
Cheers
Jim

Could be. :D