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Thread ID: 67539 2006-03-30 21:22:00 Quick question re power leads Miami Steve (2128) PC World Chat
Post ID Timestamp Content User
442164 2006-03-30 21:22:00 I have some builders at my house to do some exterior work and they need power for their compressor. I offered to run an extension out a window for them, but they insist that they need to plug the compressor directly into a socket otherwise it just blows fuses.

Is this possible? I am not keen on giving them access to the house. What difference can it make if the appliance is plugged in directly or via an extension cable?
Miami Steve (2128)
442165 2006-03-30 21:33:00 It should make no difference whatsoever. somebody (208)
442166 2006-03-30 22:09:00 As long as your "extension" lead is of sufficient current carrying capability and not of undue length it's OK.

If their compressor has a high "starting current" (and it will have) and there is too much voltage drop over that short start-up period (due to your undersized or long extension lead) then the compressor may "stall", drawing a high current for a prolonged period, blowing the fuse.
godfather (25)
442167 2006-03-30 22:22:00 As long as your "extension" lead is of sufficient current carrying capability and not of undue length it's OK.

If their compressor has a high "starting current" (and it will have) and there is too much voltage drop over that short start-up period (due to your undersized or long extension lead) then the compressor may "stall", drawing a high current for a prolonged period, blowing the fuse.
Thanks gf. That's pretty much how they explained it. They reckoned my leads were not heavy-duty enough for the job. Guess I'll have to find another solution.
Miami Steve (2128)
442168 2006-03-30 22:49:00 If they do get power from you probably a good idea to switch off computer during startup. Greg (193)
442169 2006-03-30 23:25:00 If they do get power from you probably a good idea to switch off computer during startup.
Done that, but thanks for the warning. :thumbs:
Miami Steve (2128)
442170 2006-03-30 23:56:00 I really can't see there being a problem here owing to the assumption that it's just one small compressor and it's fairly close to the house which i assume has a healthy main and all the rest.

However, motors tend to draw a lot on start up, and if you had an extremely long thin cable powering the compressor, then there would be quite a lot of voltage drop, and the motor would have a longer more painfull startup. If this were the case, It would be likely to take the breaker down owing to the extended time of high startup current. It's also not that good for the motor.

I'd say the builder has had this problem, bought a nice fat extension cord, and wants to do what he/she knows to work properly rather than risk it by using your cable(s) of unknown quality.

There's also the safety issue of earthing and so forth. Allthough i'm not a builder, i often work similar situations, and there is no way i will power up my toys using anything but my own cables. I need to be sure of healthy supply and healthy earthing. I've seen too many dodgy extensions to risk any other approach. Many builders could say the same.
personthingy (1670)
442171 2006-03-31 00:06:00 I'd say the builder has had this problem, bought a nice fat extension cord, and wants to do what he/she knows to work properly rather than risk it by using your cable(s) of unknown quality.

Then get the builder to leave the HD cable for you to drop out the window, catflap etc. Heavy duty cables aren't that expensive now at the Warehouse or big hardware chain. The Warehouse had a heavy duty red one labelled suitable for contractors. I won't use other peoples cables now if they haven't got moulded plugs on them as I've found too many are wired incorrectly.
PaulD (232)
442172 2006-03-31 01:23:00 Then get the builder to leave the HD cable for you to drop out the window, catflap etc. Heavy duty cables aren't that expensive now at the Warehouse or big hardware chain. The Warehouse had a heavy duty red one labelled suitable for contractors. I won't use other peoples cables now if they haven't got moulded plugs on them as I've found too many are wired incorrectly.

The "heavy duty" label on Wharehouse et al cables is not a good indication. Often its just 1.0 mm csa cable, or if you are really lucky 1.5 mm csa.

A "real" heavy duty cable would be at least 2.5 mm csa
godfather (25)
442173 2006-03-31 02:07:00 A "real" heavy duty cable is heavy. That's because it's got more copper in it. Graham L (2)
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