3 Phase Dis Board Incomer

[nandrews87]

Having a quick discussion in work with regards to sizing the main incomer of a three phase dis board. Can someone please tell me how the correct way to size the main incomer of a three phase board or single phase for that matter

Cheers

Folks

 

[Plonker 3]

Well it's switch so what do think it needs t be capable of doing?

 

[MDJ]

Having a quick discussion in work with regards to sizing the main incomer of a three phase dis board. Can someone please tell me how the correct way to size the main incomer of a three phase board or single phase for that matter

Cheers

Folks

um,no, you first what do you think?

 

[Darkwood]

More details please! You have given us no info to the set-up and whether its domestic, commercial or industrial and what is the nature of the systems it supplies.

 

[MDJ]

Well it's switch so what do think it needs t be capable of doing?

It might be able to make the tea or even tell the time lol

 

[gnuuser]

if you know the current requirements of the equipment it will be supplying its simple math and use of ampacity tables.
and its a matter of getting the proper hardware too
you should already be able to figure this out.

 

[nandrews87]

Its a three phase board so clearly commercial/industrial. Board would supply 8kw heater, 15kw cooker, 2 x 32amp socket circuits, 4 x lighting circuits and 3 x 32 amp commando sockets. its my opinion that a 125amp breaker would be enough based on previous experience but what I want is the theory/calculations to making such decisions.

 

[Plonker 3]

Why do you think a 125 amp BREAKER is what is needed?

 

[nandrews87]

As I have already said from previous experience working on 3 phase dis boards, What would you recommend Dillb?????????

 

[Sintra]

I would be looking at what type and rating of protective device is feeding the board.

 

[Plonker 3]

Then choose a switch accordingly.

 

[trev]

Its a three phase board so clearly commercial/industrial.

I've seen houses with 3 phase boards.

 

[Guest55]

maths ? your kidding right ?

just size your main switch to be = or > than the current rating of the upstream device.
you cant go wrong using that.

 

[Plonker 3]

You know what the next question is going to be now don't you?

 

[nandrews87]

Sintra the board in question is the example giving in an assignment question to someone I work with so that info is not included.