Distribution board cable.

[Lc85]

We are replacing a single phase lighting DB with a 3 phase DB. We are also replacing the cable that goes from the substation to the DB.

This new DB will be used for lighting circuits( we will change existing for LEDs) and we will leave spare ways.
My question is how do we size this new cable from substation to DB to take into account future expansion.

The distance between the substation and DB is approx 200m. And the existing cable CSA is unknown.

Thanks

 

[ScottyUK]

Your cable will almost certainly be sized to meet volt-drop and / or fault disconnection times. When considering the latter, don't forget to allow for the impedance of the load circuit too.

 

[Lc85]

Scotty,
Thanks for they reply. Do you know of any examples I could have a look at? The only load we have details of would be the led fittings.

 

[ScottyUK]

I haven't got anything to hand at home, might have something at work.

 

[Lc85]

Got a hold of the sld for this board.

Currently the existing board is single phase and is fed from panel 2 cubicle 1 of a 3phase switchboard. This cubicle also feeds another single phase board and has a spare way.

If we were to replace the distribution board in the field with a 3phase board. Can we reuse it's existing feed (60/25A) from the switchboard or would we have to give it a new 3 phase feed?

And as mentioned previously we only know the load of the new lights. So for rough pricing purposes can we use 25A as Ib for the new cable from the switchboard to the DB in the field?

Thanks

 

[Lc85]

As panel 2 cubicle 1 split into 3 single phase loads, am I being daft in assuming we can reuse one of these to feed a three phase board?

We have panel 5 cubicle 1 in the switchboard which is free. 160A/160A. So for rough pricing purposes we could use this to feed our new 3 phase board in the field and use 160A as a basis for cable sizing?

Thanks