Three Phase Flex for compressor

[reb78]

So, linked to this thread: http://www.mig-welding.co.uk/forum/threads/35-amp-fused-isolator.82396/

I need to get some flex for my new (to me) compressor. What is on there is as pictured below? This looks like four core armoured cable with L1, L2, L3 and Neutral. Has the armour been used as earth? I guess its more conventional to use five core? Could you recommend a suitable cable? It probably doesnt need to be armoured (this is going to be situated well out of the way and no risk of mechanical damage) unless that is a must for three phase. The flex length will be no longer than 4 metres in case that makes a difference.

The earth connections inside the unit were very loose, potentially not connected - so will rectify this with the new cable. You can see the connection as I found it below. (i thought i had a pic of the whole junction block but i cant find it).

Plan is to run it from a socket in the shed next door using a 32 amp socket to an isolator in the same shed as the compressor and then into the compressor. Any issues with this?

 

[MattH]

I've just ordered a couple of metres of SY flex to hook up my 10HP comp.

https://www.ebay.co.uk/itm/ALL-SY-C...var=470406046963&_trksid=p2060353.m1438.l2649

 

[dannyp]

4 core I’d have thought. 3 phases and earth . Can’t see it needing a neutral

 

[reb78]

Its got blue, yellow, red and black in there. So I think that includes a neutral? The earth on the junction box isnt connected to anything at all on the flex. I wish i had a pic of the whole junction block above as you would see the connections fully. Will try and get one later.

 

[carbon]

To run just a 3 phase motor there is no need for the neutral just the 3 phases. If there’s a contractor that has 240v coil then a neutral would be a good idea

 

[sako243]

Used superelec at work and they have good prices and good quality cable. Kind you we were talking single core 150mm2 cable so wasn't what you'd call cheap.

Boy those were fun to route, cut and crimp. 8h two of us managed 6 crimps on three cables. Space was tight is all I'd say.

 

[reb78]

just remembered, I have a copy of the manual. Does this explain anything?

It doesnt state the gauge of cable to use though - any advice on that? It also doesnt look like it was earthed before unless they were using the armour sleeve (sure i have read of that?)?

 

[piman]

Hello Reb78,

the control is 240v so you do need a neutral.

I wouldn't use wire armoured for this application, SY as suggested earlier is good but do get 5 core and earth the flexible sheath.,

 

[reb78]

Thanks. So will 6mm2 be sufficient or is that over/underkill? Looking at the tables online (http://www.cable-ratings.co.uk/), they seem to suggest 4mm2 would be ok, but would rather someone who knows what they are talking about confirms!

 

[brightspark]

4.omm or 6.0mm as for bonding the braid it isn't necessary just use the manufacturers recommended glands . the braid is not classed as an exposed conductive part

 

[brightspark]

the armoured feeding the comp was using the steel wire armour for the earth and is a 4 core 3 lives and a neutral , the control gear being 240v .if your using sy cable you will need a 5 core cable . one core being the earth

 

[reb78]

Understood. Thanks!