Thread: Do not use extension lead

Woodwould,
That does sound strange and I wonder what the game is. Perhaps they are intent on dodging any warranty claims. The instruction manual should have power supply info in it. I am sure that a good quality lead would be ok.
Regards
John

Originally Posted by Woodwould

I just bought a portable thicknesser and table saw from Hare & Forbes and the sales person told me not to use the machines with an extension lead because the voltage drop could damage the motors.

I'm aware that voltage does drop off when using extension leads, but is this simply a right royal bit of ar5e-covering?

Surely the whole premise of these portable machines is for them to be used for site work where often the only source of power is via an extension lead from the builder's pole?

I fully intend to plug the machines into power points in my new shed (once it's been wired), but in the mean time, and for occasional cutting of large sheets and planks that are too large for the shed, I will want to use the machines outdoors on the end of an extension lead.

Are Chinese electrics really that bad?

I'm concerned now and don't want to cause damage or void the warranties. What are everyone's opinions on this?

As long as the machines use a 10 amp plug, you should not have a problem using them with an extension lead. Just be sensible and use a single good quality lead which is no longer than necessary for the job. And read your warranty information. As long as it doesn't say you can't use an extension lead, you should be safe. As you say, these machines are designed for site work, not to be hard-wired.

And Yes, Chinese electrics tend to be their weakness. But to say you can't use an extension lead would mean the tool fails the "fit for purpose" provisions under law, and I think you would have a good case against the vendor.

No, I'm not a lawyer or expert in comsumer law, so take all the above with a grain of salt.

I've got a 15 amp lead with 10 amp domestic fittings that I've used for all sorts of outdoor activities including welding. I would have thought that would have sufficed.

The thicknesser manual mentions using a 13 amp lead and the saw manual says to use an "outdoor rated extension lead".

I'm just concerned that these Chinese machines are more fragile than I thought.

I have forgotten much more than I have remembered, unfortunately, but I believe all the responses are correct.

The voltage drop, what there is, of your 15 Amp cord is less than that of a 10 Amp, because of the higher gauge, and would be the way to go, in my opinion.

If you needed to have a warranty claim, how would they know if you had used an extension lead, or were plugged straight into a GPO?

Unless you told them.

Originally Posted by Geoff Dean

If you needed to have a warranty claim, how would they know if you had used an extension lead, or were plugged straight into a GPO?

Unless you told them.

In the words of Bart Simpson - "I didn't do it, nobody saw me do it, there's no way you can prove anything!"

(Puts on electricians hat) Using an extension lead will not damage the machines in any way.(Unless you are attemping to run them at the bottom of the swimming pool of course ) Worst case scenario if you are drawing your full current of 10 Amps on a 20m long HD extension lead you will have a voltage drop of 6.4V. Permissable VD (for cable selection) is 5% or about 12V.
I have no idea why they would advise that.
(Removes electricians hat and goes back to wasting time till knock off)

A small voltage drop won't matter..... I just means the motor will develop a little less power.

When using you table saw you will just have to control the rate of feed.... you have to do that anyway to allow for different woods and depth (height) of cut anyway. The same applies with the depth of cut with the thicknesser.

Motors burn out if you overload them and they get too hot. Just observe the temperature of your motors by the way... the cheaper motors are often running near the limit of their design and tend to overheat ( low duty cycle) The bottom end of the market is designed for short occasional use.

I turned some big tough stuff on my small lathe.... just means lighter cuts and go have a coffee or talk to the Missus every now and then (But don't take the wood chips inside or else)

Regards,

Chipman

What the others said.

An excessive Voltage drop will kill motors because they draw more current at the lower voltage from what I recall as a electrical engineering student a few years ago. (VI characteristics of electric motors).

Voltage drops are voltage drops whether they are due to internal wiring, extension leads, dodgy GPOs or dodgy wiring in the machine.

The motors don't have inbuilt intelligence that decide to only self destruct if the voltage drop is due to an extension lead

Electrical advice from salesmen should be taken with a grain of salt but double checked as you have done.

Excellent news and advice gents. Much appreciated!

Here is every thing you need to know about extension cords...

http://www.stealth316.com/2-wire-resistance.htm

I hope this is the correct time and place to mention that, if a cord is wound about a metal core, it will heat up when in use.

Therefore, it is prudent to ensure that cords are wound about plastic, cardboard or wooden cores when under load or, of course, are fully unwound if a metal core is used.

Originally Posted by Old farmer

I hope this is the correct time and place to mention that, if a cord is wound about a metal core, it will heat up when in use.

Therefore, it is prudent to ensure that cords are wound about plastic, cardboard or wooden cores when under load or, of course, are fully unwound if a metal core is used.

Cords should always be completely unwound no matter what type of core or reel. Using the lead wound up derates the cable by as much as half depending on the number of layers in the coil. This means, as OF said, overheating and increased voltage drop and consequently higher current draw and reduced performance. (extreme case)

wow this thread really caught my eye! I've got to fully wire my shed for lights & power points for all my equipment but for the moment until i deceide on the final placement of machinery i've been running it all from extension cords. I only use the heavy duty rated outdoor extension cords but they are still 20m cords.
The power cords really only need to be 5 - 10m long total so perhaps i should buy a short 15a extension cord for the interium? i sure as hell don't want to damage my new equipment!