3 Phase feed with 2 cables

[mattmoo1974]

As above really, Massive green house converted into small units.
Basic supply was single phase and when he asked for 3 phase this is what they ve done.
Basicly you ve got 2 phase and netural from one cable and a seperate earth, 2nd cable has 1 phase another CPC.
Its a private supply, All this is connected into a metal clad box.
I only noticed because i was getting a very high Ze reading and traced it back. There are 3 CPC's tagged down to said box.
Where i found a loose connection and got my Ze back down.
Any views commets etc etc This box is Pre meter by the way.

 

[malcolmsanford]

How are the conductors entering the enclosure and is it a metal clad enclosure.

As such though not the way I would do it, there is nothing inherently wrong just IMO poor installation practice. What could be a problem is how the phases are entering the enclosure if it is metal clad. The 3 phases Neutral and CPC should all enter the enclosure at a single entry hole, or if they enter via separate holes then the enclosure should slotted to reduce EMF.

 

[mattmoo1974]

Its glanded to it malc and connector blocked inside
Is it a lazy way of getting the 3 phase there rather then using a 5 core cable?
When you say slotted can you explain a big more, Iv just got up and had a few STella's last night When will i learn.

 

[malcolmsanford]

If the 5 cores were going into the enclosure through different holes, so let's say you had the 2 phase and Neutral with the CPC entering through one hole and the newer cable entering in via another hole then what you should do is slot between the 2 holes. In bygone times you would just cut with an hacksaw between the holes ie slotting it, now I would use a jigsaw.

 

[mattmoo1974]

A font of knowledge as per Mr Malcolmsanford i thank you kind sir

 

[Knobhead]

To be honest this doesn’t sound a good idea using two cables.

As regards glanding the cables as Malcolm said as slot has to be cut between the holes, also the lock nuts must be brass to stop Eddy currents. You could also get problems with Eddy currents in the armouring. I can see you getting called back to sort things out in the furure.