Using Extension Cords to power workshop?

[mr chippy]

Hi,

I have a garage which I would like to use as a workshop. The garage does not have any power and I can not have it wired for power(it is a rental property), my only option for power is to run an extension cord. I have a router, 1 hp bandsaw, 1200W planer/thicknesser and a 1300w shopvac/dust extractor which I would like to use. I would need about 40 metres of extension cord to reach my garage. I know that a voltage drop occurs when a long extension cord is used and that the drop in voltage will damage the motors in my tools.

Can anyone tell me if or what size extension cord I could use (in Amps) to safely supply power to my tools, it needs to be 40 metres long?

Thanks for any assistance,

Tomas

[echnidna]

Use a 15 amp lead to the shed.
From there on you could use some power boards and short leads to the equipment.

[Eli]

I split the cost to install a single powerpoint in the shed w/ the landlord, and then used a set of switched point leads from Bunnies. The one I used has eight outlets, one meter spacing, and ears to mount them with screws. I ran them along the top of the wall, giving me switched outlets all over the shed, high enough so the kids can't reach them. They're coming with me when I move, it was worth it to have the first one put in. My cost was $75 for the install, and about $40 for the powerpoint lead.

[Harry72]

40m is a long stretch, find the heaviest guage cord you can. Even approach a sparky to make you a custom job, you will need to use OFC cable for flexibility.

[Ivan in Oz]

Harry72,
Please bear with me.

OFC

Oxygen Free Copper....Hmmmm?
Optical Fiber Cable.....Nah! This is Power; not Signal.

I'm thinking Oversized Flexible Copper.
I have some made of 2.5mm2 Flex,
a tight squeeze into the Plug and Socket,
but the DO Fit, and work well,

[mr chippy]

Thanks for all the replies. I have seen 15A extension cords made with 2.5mm wire, seems like what I am reading here leads me to think that will do the trick.

Thanks for the assistance.

[Barry_White]

I use a 2.5mm2 Round Orange flexible lead to run a pump 50 metres away. They actually make 10 amp plugs that have a larger entry into the plug to accommodate the larger 2.5mm2 Round Orange cable. You can buy the cable by the metre from electrical wholesalers and get your sparky to make it up.

[niki]

I think that it will be better to use "single wire" cord (i.e.. rigid cooper wire) as you can see on the pics, single wire can transfer up to 32A but a bundle (or flexible wire) only 16A.

You can input your own parameters here
http://circuitcalculator.com/wordpre...er-calculator/

If you will use 15A (3,600W), the voltage drop will be around 4.6V (1.93%) calculated from this site...if it's bad for the machine...I don't know...
http://www.powerstream.com/Wire_Size.htm

I used a single wire cord to a distance of 80 Meters and did not have any problems loading it to 4,000W (16~17A).

niki

[Harry72]

Yes Ivan OFC= Oxygen free copper. I think most extension cords and flexible cables are made from it, all the wiring in the automotive and audio industry is ofc.
You should see the extension cords at my work... they're about 50mm in dia!(obviously 3phase, about 15~20mm2 cable!)

[soundman]

A couple of clarifications here...... the term OFC for "Oxygen Free Copper" is completely irrelivent to electrical cables as supllied in this country.

Truth is it is problay a completely irrelivent marketing term when applied to any copper cabling made out of good quality non recycled copper anyway.
It is just another overhyped HIFI concept.

As to using cable other than an australian approved three core flex........ that would be most unwise.

you might get away with 15 amp ( 1.5mm2) flex but 20 amp( 2.5mm2) flex would be a far better choice.

As for the plugs .... the clipsal items are the go just ask for them in HD version..... the HD version is the one with the larger cable entry designed to accept either 15 amp heavy duty cable or 20 amp ordinary duty cable.

do not be confused there is no more copper in heavy duty cable just the outer insulation is thicker.
A heavy duty cable will not help your voltage drop.

you would problay be wise to plug a portable earth leakage device( safety switch) in the house end of the extension cord if the house isnt fitted with earth leakage breakers.

cheers

[Harry72]

Your right OFC is a audiophile con, because its actually not technically any better conductor than normal 4N copper wire!

http://en.wikipedia.org/wiki/Oxygen_free_copper

[elkangorito]

The voltage drop across any cable is directly relevant to the current passing through it. Cable sizes with respect to voltage drop, cannot be "guessed".

Using ASNZ 3000:2007, I've just done a quick cable size estimation for the following conditions;

1] cable route length - 40m.
2] maximum cable load - 15 Amps.
3] maximum permissible voltage drop as per this standard - 5%.

The minimum size cable that can be used providing a current not exceeding 15 Amps is used - 2.5mm squared. Motor starting currents will not affect this value unless time between starts is very frequent (Eg once every 5 mins). Please also note that a voltage drop of 5% @ 230v is about 12v. If you wanted to halve this voltage drop, you would need to use a minimum 6mm squared cable.

You are not permitted to use "building wire" (single core, single insulated) to make an extension lead. Nor can you use double insulated single core cables to do this. These types of cables/wires MUST be enclosed appropriately ie in electrical conduit. This type of arrangement is considered a fixed installation & other rules will apply.

I could do a detailed calculation using ASNZ 3008.1 but I feel that this is not necessary unless more information about how you plan to run your extension lead, is revealed.

[echnidna]

Mr Chippy's biggest machine is only 1300watts. This is far below 15 amps.
So a 15 amp lead will be quite adequate without excessive voltage drop.

If you got nothing to do then calculate the voltage loss based on his expressed needs instead of against a 15 amp lead.

[wheelinround]

This has proved an interesting read.
I have had to use extension leads to shed & garages in the past.
One thing that hasn't been mentioned here is ambient temp of the lead.

I found that in mid summer the lead itself was so damn hot and that was even after a break of 2 hrs during heat of the day. It got to the point I had to move the cable into the shade during that time of day.

What effect will ambient temp have on the calculations??

[NCArcher]

Mr Chippy's biggest machine is only 1300watts. This is far below 15 amps.
So a 15 amp lead will be quite adequate without excessive voltage drop.

If you got nothing to do then calculate the voltage loss based on his expressed needs instead of against a 15 amp lead.

The 1300 watts is the dust extractor, you need to add the 1200 watt planer/thicnesser as both will be used at the same time.

A 15Amp lead 40m long with 2500W of power will have a voltage drop of just over 12V. A bit too high IMO. Go for the HD 2.5mm (20Amp) extension lead. The voltage drop will be kept below 8V which is well within the 5% guide line.

Wheelin - The current carrying capacity and VDrop figures quoted are based on an ambient temp of 25 deg C and a max temp of 60 deg C. Although temp does have an effect it's not enough to worry about. Temperature is a problem when the cable cant dissipate heat because it is surrounded by insulation.
With flexible cords/extension leads a bigger problem is leaving the cable wound onto a spool. With 4 layers wound onto the spool the cable has to be derated by a factor of 0.4. i.e. if the unwound cable is capable of carrying 20 Amps when 4 layers are wound onto a spool or reel the cable can only safely carry 8 Amps. (So Mr Chippy, don't do this)