Feeding 250 amp 3 phase board direct from buzz bar need isolatir

[Darkwood]

I think tbh you need to know exactly what is existing, you cannot design a system by guessing what's existing, like I said earlier, small mistakes cost big in this side of the industry.

 

[Lintay]

I think tbh you need to know exactly what is existing, you cannot design a system by guessing what's existing, like I said earlier, small mistakes cost big in this side of the industry.

If the fuses are 100amp can I feed the dist board directly with 35 mm tails thx

 

[Darkwood]

Yes but you have to look at the bigger picture here, can the fuses be uprated again ie.. is the cable big enough to do so, you want to avoid forcing limitations on future additions, they may just have 100amps because of the low demand but fitted a 200amp system for expansion, we lack the info to give you a true informed reply but your boss really should have done all this and supplied you with the correct gear to start with with which I have my doubt he has.

 

[Lintay]

Yes but you have to look at the bigger picture here, can the fuses be uprated again ie.. is the cable big enough to do so, you want to avoid forcing limitations on future additions, they may just have 100amps because of the low demand but fitted a 200amp system for expansion, we lack the info to give you a true informed reply but your boss really should have done all this and supplied you with the correct gear to start with with which I have my doubt he has.

Maybe he couldn't get a 100amp dist-board hence why he got the isolator?but then the cost in price is a huge difference?But he had said to use 25mm tails.il have to run through the design with him tomorrow,thx for the advise really appreciate it.
I only started new job last week so had to make sure I knew what I wax on about before speaking to him.thx

 

[Toneyz]

what 250A D.B. have you been provided with ?

 

[Lintay]

what 250A D.B. have you been provided with ?

Will check in the morning

 

[westward10]

Try and be open with your boss about your lack of experience with this.

 

[Lintay]

I told him first day on the job, but he was the one who designed it and ordered bits

 

[LeeH]

Tri -rated?

Probably be ok but the ratings are based on 90degC remember with tri.

 

[Darkwood]

Probably be ok but the ratings are based on 90degC remember with tri.

You raise a good point but tri rated still has a higher capacity at 70c plus we do not know the switchgear, the busbar will be ok for 90, I install this stuff all the time and you can maintain the 90c ratings if you choose the correct gear, otherwise it's pointless making it.

 

[Lintay]

what 250A D.B. have you been provided with ?

SE48B250 KQ16 TP WAY 250 type B DIST
THX

 

[Pete999]

I'm working in a warehouse and replacing the old fuse boards with a new 3 phase board.
The board will be sitting directly above the buzz bar im not sure if I need to put in an isolator in between them to isolate the 3 phase board?
Thx

Must be a loose connection if the busbar is buzzing

 

[Lintay]

If I replace the main switch which is a SE 125SW3L switch disconnector with a 125 a Mccb I can come straight of the bus bar to the dist board?

Must be a loose connection if the busbar is buzzing

lol

 

[westward10]

You are not going to be able to do that.

 

[Lintay]

You are not going to be able to do that.

Why