3 Phase 'Radial ring main' ?

[Scrums]

Just a quick enquiry to those that might know.....I have 4 x 3 ph machines all running off separate breakers in the main box, one's on a plug, the others are hard-wired to switch boxes.

I'm just about to buy a Stromab 650 in 3ph guise and wondered - I work entirely on my own, can't use two of these machines at once, so - what's the problem with wiring this from the unswitched side of one of those a - spur if you like, obviously the breaker would have to be up to it.

Dangerous/impossible /against the rules - your comments please ?

Chris.

 

[andersonec]

Chris, If you don't get an answer here, go to the Screwfix site, then click on 'Community' you will find sections for all the trades and as on here, they are very very helpful.

Andy

 

[doorframe]

Hi Chris.

The standard wiring with 3 phase is to wire a radial, taking 3 phases, a neutral and an earth from the CCU to each isolator (switch box) in turn in a radial circuit. Each Isolator can supply 1 machine direct or 1 3ph socket.

Without knowing your MCB or cable size, I would say a hesitant "yes" to wiring from the unswitched side of one of the isolators (in the same cable size as is already supplying it) to the next (new) isolator, and from the isolator to your machine or new socket.

If you have a 32A breaker and 6mm cables then go for it.

Edit.. just checked ...your machine is 5.5hp according to web... equates to 7-8amps (3 ph) so you should be fine with the above but MUST check cable size.

This is from a US site...
http://www.klocknermoeller.com/hp.htm

A quick 'rule of thumb' method I've seen often used in UK is

HP x W(1HP) / 690 = A

So...5.5 x 750 / 690 = 6A (3ph)

Your new machine will have a rating plate on it which will give all necessary info.


Hope this helps.

Roy

 

[Windy*miller]

But bear in mind (and you did ask this) that although it sounds like a sensible thing to do it is almost cetainly against the rules for you to do it yourself. I'm kind of assuming that if you were an electrician you wouldn't be asking the question.