3 phase to single phase

[sparkysean]

Hi people i have to step down from a 3 phase to a single phase for a 13amp fused spur which will be used for a fire distern.

I have a 3 phase board and would like to install a single phase isolater which will then feed the fusible spur for the fire distern, i would like to know any regulations or advice.

thankyou.

 

[Spudnik]

Hi Sean(?),

If you have a 3ph DB, as the load will be fairly low, you can just install a single phase 6A MCB on a spare way in the board for the fire alarm system.

Try and make sure you install the same make.

 

[sparkysean]

cheers for the input jason, great help.

 

[Sparky-Tom]

Also if you do happen to install any more single phase MCBs to the system in future, try and distribute them across the three phases, to keep the loading balanced.

 

[sparkysean]

cheers tom but could i have a example of balancing the load. Dyou mean by following the phases i.e y1 y2 y3 in order

 

[Guest123]

Hi Sean.

When you install single phase loads onto a 3 phase DB you are in effect unbalancing the system by having say, a 16A circuit on one phase eg Brown (L1). Should you ever need to install another single phase load to the DB then you should install this on a different phase i.e Black (L2) and for another, Grey (L3) thereby balancing out your single phase loads across the 3 phases.

Cheers

 

[Spudnik]

Wait till you have to deal with 2 phase 3 wire.

Now THAT is a P.I.T.A.!

 

[sparkysean]

thanks everyone for the input, i have a new job as a maintenance engineer and my expertise lies in domestic and new builds so for the next few months i'll most probably be asking many questions that you real pro's know straight off your heads, but thankyou again and see you all soon.

 

[Sparky-Tom]

Sorry I should have explained it a little more in-depth, thanks Lenny!

Sean, is this your first time working with 3-phase systems?

 

[sparkysean]

i have installed 3 phase amoured cables but never actually worked on 3 phase in a maintenance role