# 3 phase wiring advice



## Andy (30 Jul 2021)

Hi All
I have just acquired an overhead router and need to put a plug on it. It requires 4 core cable but I'm going to put a 5 pin plug on it as I have a 16amp 5 pin socket already conveniently located nearby. Existing wires are earth, blue, brown and black as per picture below. Question is, which pins on my 5 pin plug do they all go to?
thanks in advance, Andy


----------



## rob1693 (30 Jul 2021)

Brown black grey go to l1 l2 l3 neutral goes to n earth goes to earth terminal


----------



## rob1693 (30 Jul 2021)

You seem to be missing a phase on your wiring


----------



## Spectric (30 Jul 2021)

Do you know how old the wiring is, or have you belled out the wires as it is possible that it is just three phase and earth with no neutral, they have used blue instead of grey. Quick check is what is the starters coil voltage, 230 or 400.


----------



## rob1693 (30 Jul 2021)

Or blues been used as a phase if it doesn't require a neutral if so connect blue to l3


----------



## Andy (31 Jul 2021)

Thanks for the responses guys. I'm afraid I don't know how old the wiring is - it's an old machine - a Samco Mini Router ( I don't know why they call it a mini router, it certainly isn't small!) 
Spectric - are you saying that if the starters voltage is 400 then they have used blue instead of grey?
thanks, Andy


----------



## deema (31 Jul 2021)

Get a sparky to wire it up, electricity doesn’t take prisoners, doesn’t give you a tickle as a warning, if you get it wrong your dead and wrong. I say this as you don’t know the difference between line and phase voltage, or the basics of electrics from your responses.


----------



## guineafowl21 (31 Jul 2021)

Brown/blue/black = L1/L2/L3 by the looks of it. A couple of my machines came wired like that. Get some modern 1.5mm2 5-core flex, ideally H07 RNF, and wire as:

Brown/black/grey = L1/L2/L3.

Hook up earth and neutral (N) but terminate the latter in a Wago connector at the motor box. It may come in handy for a worklight or similar. Swap any two L connections if it runs backwards.


----------



## Spectric (31 Jul 2021)

Andy said:


> Spectric - are you saying that if the starters voltage is 400 then they have used blue instead of grey?


If a machine does not use the neutral then you only have 400 volts so the contactor coil has to be 400 volts, if it is 230 volts then it must use the neutral.


----------



## Alli (31 Jul 2021)

I don't know much about these things but I remember a conversation with a sparky mate I was giving a hand too down an old farm. It had a 2 phase and neutral supply to the farm and I asked why it wasn't three phase as isn't this is what big motors normally need, and I am pretty sure he replied no, you can get 2 phase motors! - it was a good few years ago now, so I might of mis-remembered.

I only mention it as you seem to have 2 phase and neutral if the wiring colours are correct and the blue hasn't been used for a phase conductor. Just before you see that magic smoke you might need to find out which cable is doing what.


----------



## Andy (1 Aug 2021)

Thanks for all the help guys, this is really useful


----------



## rob1693 (1 Aug 2021)

A picture of the motor plate should reveal how many phases are required


----------



## Andy (1 Aug 2021)

Here's the motor plate:


----------



## rob1693 (1 Aug 2021)

I presume tri phase in Italian is 3 phase so definitely not 2 its more than likely just 3 phase and earth but if your not competent to determine that with a multimeter like deema said get in a spark


----------



## deema (1 Aug 2021)

Hmm


----------



## MikeK (1 Aug 2021)

I've seen similar motors in Italian machine shops. This is an Italian asynchronous three-phase two-speed motor. It is rated at 3HP (2.2kW) or 4HP (3kW) and the speeds are 1400 RPM or 2800PRM. I've never bothered to look at the insides of the motor, but I think this motor is a delta configuration with 415V between phases. There might be internal taps in the motor housing to change the speed.

The IP44 means it is protected against solid objects greater than 1mm and water from all directions for up to five minutes. I think all of the motors I saw in machine shops with liquid coolant were IP55 and IP65.


----------



## Sideways (1 Aug 2021)

Two speeds quoted => this is a motor capable of being wired as a 2 pole or a 4 pole configuration. Means it has two sets of field coils that can be configured differently.
It is more complex than a basic motor, it operates at a voltage that will kill you without hesitation, and people who are not expert in the field are speculating in this thread.
"This is really useful" advice is tipping over into "this is really dangerous" because he is not competent to be playing with this, you are indirectly encouraging him.
I can see a Darwin award being given in the not so distant future.

_Your children can't sue the internet for negligence ..._


----------



## OldWood (2 Aug 2021)

Further agreement on the competence of the OP, and correspondingly those giving advice. This is not an area to go wandering into without experience and knowledge.

The additional problem is that most sparkies will have a working knowledge of domestic wiring but it requires someone from the industrial world and hence familiar with 3 phase and associated motors to resolve this.

I further agree with MikeK that this is a 2 / 4 pole motor, and hence will have two off 3 sets of wires coming from the motor and that requires further experience to be able to manage. There should be a switch to select low or high speed. 

Andy - please do not address this yourself, but find someone who has professional qualifications in wiring this type of machine. 

I should add, again from experience in this area, that unless the motor is geared / pulleyed up to considerably higher revs - ie 10,000 - the 1400/2800 revs will give a very poor finish. Just think how fast your bench router runs with its series wound single phase motor. The way this was done on a machine I helped to restore, was to drive a 400Hz ac generator from a mains (ie 50Hz) motor and drive an induction motor from that generator giving 10,000 + revs. It was built originally to machine the bulkheads for the WW2 Mosquito aircraft.
Rob


----------



## Andy (3 Aug 2021)

In response to OldWood, yes there is a switch to select between low and high speed - see below

There is a pulley giving speeds of 8500rpm and 17,000rpm

Not quite as fast as a Wadkin which I previously had the use of, giving speeds or 12,000 and 24,000rpm, but should be sufficient for my purposes and also much more manageable for a small workshop than the Wadkin (particularly when it comes to moving it!)

cheers, Andy


----------

