3 Phase Dis Board Incomer

[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.

 

[Plonker 3]

No but the loading of the new DB is.

besides, what was there answer to the said question?

 

[nandrews87]

This is the rule of thumb I normally use but giving this info is not available I presume there must be a method to work it out based on the load on the board

 

[Plonker 3]

Of course it is,that's how you always work out a OCPD isn't it?

 

[nandrews87]

No but the loading of the new DB is.

besides, what was there answer to the said question?

There answer was to tally up total current from other loads and size main breaker on that number, I dont believe this to be right as it doesnt allow for things such as diversity factor. My approach is to size it based on device that provides protection upstream of the dis board in question but in this instance that info is not available.

 

[Plonker 3]

We'll apply diversity and you will have your answer.