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Posted By Topic: Extension Leads Volt Drop

Nov 09 2013 11:32

If you run 1.5mm flexible in air @ 10amps through gen calc with 2.5% volt drop it can only go out to 19mtrs.
Can someone explain why they sell big 30 mtr extension leads as sometimes it could exceed the loop impedance and VD parameters.

Nov 09 2013 20:42

not many 240v tools pull the full 10A, and very few would run continuous... the thing to watch on long leads is the Impedance with regard to the fault current generated to trip the protective device... 2 or 3 30m leads joined together with crusty corroded pins not good

Nov 09 2013 21:40

Seen ~6x 30m extension leads with ~1kW grinder off end of it, due to site being too cheap to invest in another Lifeguard + Lifeguard extension lead.

Another site I heard a tale of a tidy welder who wrapped his excess extension lead tightly round a piece of scaffold, which ended up welding itself nicely.

Nov 09 2013 23:23

One job I saw voltage drop to about 180V when boiling the jug in our smoko shed (yes I bothered to measure it). Also had a heater running and a 500w halogen flood.

A series of life guards, then a series of extension leads and multi boxes via the builders shed.

Nov 10 2013 06:53

While the points raised above in respect of the actual voltage and EFLI are valid, the Wiring Rules only covers the voltage drop and EFLI from the \"point of supply\" to the most remote \"point\' on a final sub circuit, usually a socket outlet or the like.

The extension cords should comply with AS/NZS 3199 in terms of conductor size verses length.

There is NO overall requirements made to cover the operation of the whole system, electrical installation and the items connected to the installation. It their was how would this information be given to every man, women and children?

We can all point to extreme cases of excessive length of extension cord use, the electrical design industry on its own can\'t control what consumers or end users do!

As a control measure the best we can do is to design electrical installations to the best of our ability and point out that some arrangements are undesirable from an electrical safety view and may not provide the ultimate electrical safety.