3 phase supplies for table & band saw

[Marine electrical fitter]

Hi all,

I have been asked to install individual three-phase supplies for a band saw and table saw.
Having trouble figuring out the correct cable / breaker sizes required (I’m a marine electrical fitter and it’s been a long time since doing this sort of works).
I currently have an Eaton memshield three-phase distribution board, 415V with 100A main switch.
Length of run to the saws is approx. 50m.
Band saw is 415V 3p+E 1.1kW.
Table saw is 415V 3p+E 3.5kW.
Each come with a 16A red 4 pin plug on 2.5mm 4 core braided cable.
Was considering using armoured cable clipped direct to the wall to an individual RCD protected industrial socket outlet with isolation.
Any advise on what I’m missing / formulas and calculations required would be much appreciated.

 

[Spoon]

Welcome to the forum mate.
Calculate the max amps current draw for each item.
Select an appropriate breaker for each item. Or look in the manuals and see if they suggest a size.
Then pick a cable size/type for each breaker. Take into account installation method, voltage drop, grouping factors (if applicable), environment...ect... the usual stuff.
Don't forget Part P. As they are new circuits then this work is notifiable.

 

[brianmoooore]

If the plugs are staying on the tools, you're not installing a table saw and a bandsaw, you're installing a couple of 16A 3 phase sockets, and the calculations should be for those sockets.

 

[davesparks]

16A sockets would be best served by a 16A MCB's.
If the machines are supplied with 16A plugs fitted then you can only assume that is what theanufactirer intends for them to be supplied by.

Overload protection will be provided within the motor controls inboard the machine.

 

[brianmoooore]

16A sockets would be best served by a 16A MCB's.
If the machines are supplied with 16A plugs fitted then you can only assume that is what theanufactirer intends for them to be supplied by.

Overload protection will be provided within the motor controls inboard the machine.

Only thing to be decided is 16A type B, C or D.

 

[Spoon]

16A sockets would be best served by a 16A MCB's.

If the items don't pull no were near 16A then is there much point in sticking in a 16A breaker and cable sized for it?
As long as the supply is no bigger than 16A then the socket will be ok.

 

[brianmoooore]

A 16A socket is a 16A socket. The design has to accommodate whatever someone else decides to plug in there, long after the table and bandsaws may have gone.

 

[Rockingit]

If the items don't pull no were near 16A then is there much point in sticking in a 16A breaker and cable sized for it?
As long as the supply is no bigger than 16A then the socket will be ok.

Given the wide availability of 16/3 devices, lack of challenging cable sizes... I can't seen any compelling argument for making life hard and trying to go smaller!

A 16A socket is a 16A socket. The design has to accommodate whatever someone else decides to plug in there, long after the table and bandsaws may have gone.

Agreed!!

 

[Fazz711]

As said.
You are installing 16A sockets.
You have to cover them in the design process.

 

[davesparks]

If the items don't pull no were near 16A then is there much point in sticking in a 16A breaker and cable sized for it?
As long as the supply is no bigger than 16A then the socket will be ok.

Yes you could use an MCB sized more closely to the load, but the savings are unlikely to be very much.
The advantage of making it a 16A circuit is that you can easily plug an alternative machine into it without having to alter the circuit.