Discuss Feeding 250 amp 3 phase board direct from buzz bar need isolatir in the Commercial Electrical Advice area at ElectriciansForums.net
25.0 conductors contained are not rated at 100A anyway for a triple pole supply.
Or BS7211.Tri -rated?
The isolator load tails will route back through the bus bar into dust-board
When you say isolator is it fused at 100A. If so you need at least 35.0 conductors to and from it. Have you got additional busbar clamps, I hope you are not going to pair up from existing clamps.I'm usually doing domestic work but now work for a new employer. He's gave me a 100 amp isolator to feed from the bus bar to then feed the dist-board,my boss has supplied all the materials.
So if the dis-board main switch was 100amp I could connect tails direct to busbar?
Thx guys
I'm usually doing domestic work but now work for a new employer. He's gave me a 100 amp isolator to feed from the bus bar to then feed the dist-board,my boss has supplied all the materials.
So if the dis-board main switch was 100amp I could connect tails direct to busbar?
Thx guys
You can come direct from the busbar but your conductors need to be at least 95.0, have you ever worked with this size of conductor.Thx for constructive advise darkwood hence why I'm querieing the design.
So could I come straight off the bus bar into dist-board and double up the tails?or will I need to replace the main switchwith a fused switch aswell? Thx
Yes I have to agree, you need to have a chat with your boss and explain that at the moment this maybe outside the scope of your competence and you need some guidance and assistance. I think you may also need to bear in mind that he, assuming it is a he has not really thought this through. This isn't routine domestic work as you have realised and the reality from a piece of paper can be a harsh lesson.[/QUOTE
NoYou can come direct from the busbar but your conductors need to be at least 95.0, have you ever worked with this size of conductor.
So downrate the the dist- board switch to 125. Amp?Yes you could although the main switch at the board is not likely to be an mccb but an EN60947-3, 125A isolator.
Yes I'm thinking now it's 100amp sorrySorry earlier I'm sure you said the busbar was fused at 200amp, now are you saying 100amp? It changes alot of the advice.
If the fuses are 100amp can I feed the dist board directly with 35 mm tails thxI 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.
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.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.
Will check in the morningwhat 250A D.B. have you been provided with ?
Tri -rated?
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.Probably be ok but the ratings are based on 90degC remember with tri.
SE48B250 KQ16 TP WAY 250 type B DISTwhat 250A D.B. have you been provided with ?
Must be a loose connection if the busbar is buzzingI'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
lolMust be a loose connection if the busbar is buzzing
WhyYou are not going to be able to do that.
Boss has told me to use 35mm tails into isolator then 35 mm tails to feed the dist board and to use the 125amp switch disconnector.Main switches for those boards are 125A, 160A, 200A or 250A and none offer circuit protection they are 60947-3 switch disconnectors. Off hand I am not certain if you can get a 60947-2 which offers circuit protection, if you can it will be the higher rated devices and not 125A.
My boss is telling me the dist- board needs an isolator before it incase someone wants to work on the board they don't need to kill the busbarBoss has told me to use 35mm tails into isolator then 35 mm tails to feed the dist board and to use the 125amp switch disconnector.
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