Cable diameter for long distance run

[RGi]

I'm looking to make an extension lead of over 60m to run a well pump of of the generator after storms or other power cuts. It needs to run the pump which is rated at 2400 Watts. What diameter cable is needed for this to allow for power loss over distance.

 

[flameport]

2.5mm² 3 core flex. 3183TRS or similar.

 

[RGi]

Thanx! It would be great to know how to work it out so I don't have to ask again?

 

[oldbutnotdead]

Does the pump not need to run in normal (ie not power cut) circumstances? 2.5mm TRS or SWA would do the job (but SWA isn't exactly an extension cable)- might be better getting one of those cheap site gennies from Ebay and not having a 60m cable run

 

[RGi]

Does the pump not need to run in normal (ie not power cut) circumstances? 2.5mm TRS or SWA would do the job (but SWA isn't exactly an extension cable)- might be better getting one of those cheap site gennies from Ebay and not having a 60m cable run

Thanx Oldbutnotdead. The pump runs of a buried sheilded mains, but in outages it runs of a genie and 60 m is the closest it can get.

 

[oldbutnotdead]

Thanx Oldbutnotdead. The pump runs of a buried sheilded mains, but in outages it runs of a genie and 60 m is the closest it can get.

Fair does. For future, you're looking at current carrying capacity of the cable and critically volt drop. This here calculator https://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html will do the basics

 

[EFLImpudence]

I can't get TLC's calculator to give a result

although I can do it manually with a satisfactory resut of 2.5mm² as flameport said.

 

[ban-all-sheds]

Shouldn't the starting current of the pump be considered?

 

[SimonH2]

Do you have access to the supply end of the normal power cable for the pump ?
If so, then you could fit a change over switch there and (say) a BS4343 (aka Commando) power inlet. That would avoid the need to run out a long extension lead every time you need it.

 

[RGi]

I can't get TLC's calculator to give a result

although I can do it manually with a satisfactory resut of 2.5mm² as flameport said.

I had a bit of difficulty with it myself. Any chance of the formula or a link to it?

 

[RGi]

Shouldn't the starting current of the pump be considered?

I don't know, should it?

 

[RGi]

Do you have access to the supply end of the normal power cable for the pump ?
If so, then you could fit a change over switch there and (say) a BS4343 (aka Commando) power inlet. That would avoid the need to run out a long extension lead every time you need it.

Good idea but the generator is in a different location unfortunately.

 

[ban-all-sheds]

I can't get TLC's calculator to give a result

I had a bit of difficulty with it myself. Any chance of the formula or a link to it?

What problem(s) were you having?

 

[ban-all-sheds]

Shouldn't the starting current of the pump be considered?

I don't know, should it?

Yes, because if it is high in comparison to the steady-state load you use to size the cable the voltage drop when it tries to start my be too high, and it might not start properly.

 

[RGi]

What problem(s) were you having?[/QUOTE ]


It is hard to find the answer on the page, the formula would be as easy enough with a calculator. I guess it should be possible to view the page source and get their version of the maths from the HTML or Javascript..?