Cable Length

[Freetochat]

I am planning to move my workshop, so that I can enlarge it slightly. The power supply is from my house, and is steel amour cable with a run of about 10 metres. I would need to extend the cable by anouther 15 metres to reach the new location. Is there any drop in supply issues that I need to consider, especially as the machines need 16 amps. The cable is three core with a diameter of 20mm. I cannot remember the core, but I think it is 4mm. Any advice welcome please.

 

[ike]

My W/S supply from house consumer unit is 50 metres of 4mm T/E with (I think) a 30A breaker or it may be 40A . I don't have any problem running 2 machines simultaneously (2.8kw saw, 3.0 kw P/T). No problem with volts drop starting either (but wouldn't ever need to start them simultaneously anyway). Each machine has it's own 16A circuit from W/S consumer unit.

I don't know if induction motors vary much in their efficiency or startup current characteristics and I'm just lucky to get away with it. Both machines are Scheppach. Both have what look like very chunky capacitors but haven't looked at their capacity. Can't think of any greater transient loads in the W/S than these machines.

cheers,

Ike

 

[Adam]

Try typing in your numbers here:

http://www.tlc-direct.co.uk/Technical/C ... eDrop.html

 

[davy_owen_88]

If you are extending then you will need to upgrade the cable regardless, so my advice is to upgrade to 6mm at a minimum (its about £15 more expensive than 4mm at about £55 for 25m) just to be on the safe side - you are gaining space so might end up filling it with bigger and more powerful tools so you don't want to have to rip the cable up to upgrade later on...

Voltage drop values (approx.)

2.5mm : 18mV/A/m
4mm : 11mV/A/m
6mm : 7.3mV/A/m

To work it out: voltage drop x total current x cable length / 1000 = voltage drop in volts.

The maximum permissable voltage drop is 4% of your supply voltage which is probably still around 240V - so max. voltage drop is around 9.6V.

Davy

 

[Freetochat]

Thanks for the info and link, very helpful.

 

[RogerS]

I second what Davy has recommended. I ran 4mm out to my workshop and in hindsight wished I'd gone for a larger cable. The lights dim when I fire up the table saw...mind you they also dim inside the house so maybe I've got a wee problem elsewhere

 

[Les Mahon]

mind you they also dim inside the house so maybe I've got a wee problem elsewhere

I noticed yesterday that my neighbours lights dim when I fire up the table saw!

Anyway, I would go for the biggest cable possible, as said else where the cost diferential is fairly small, and it give you future proofing.

Les

 

[RogerS]

mind you they also dim inside the house so maybe I've got a wee problem elsewhere

I noticed yesterday that my neighbours lights dim when I fire up the table saw!

:lol: :lol: :lol: :lol: