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

[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

 

[westward10]

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.

 

[Darkwood]

You have led a confusing conversation here, I was under the impression it was already kitted out with a 250amp disconnector but it sounds like you have a standard incomer.

Yes!.. these boards can be upgraded with various incoming devices, you will have to find out the lowest rated version, 100amp I think ...see here http://www2.schneider-electric.com/resources/sites/SCHNEIDER_ELECTRIC/content/live/FAQS/141000/FA141814/en_US/SE8386-RTI Catalogue_MAY_2015.pdf

If you go for the upgrade kit it will probably come complete with expansion box and you'll have to fit it all, it can be very confusing and puzzling if you have never done one as the instructions are pictorial and worse than Ikea for been easy to follow, the kit will just be as expensive as the whole board itself but your saving on tail sizes, switch fuse unit and labour so should work out better, this is the main reason I queried the original diagram you presented as you had this simple option and seems your boss is also clueless to this kind of work. Check with the wholesalers or direct with schnieder that your chosen kit is compatible with your board before getting it as there are many kits out there for there varying ranges.

 

[Lintay]

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.

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.

 

[Lintay]

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.

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 busbar

 

[westward10]

My mistake you can get 60947-2 devices, but yes you are giving conflicting information. We all get situations where we have to find a solution to a problem but we do that from experience and consulting colleagues. It is clear you don't have the experience to find that solution and you really need to sit down with your boss who hopefully will guide you or put someone with you to assist. He is being totally irresponsible if he basically shrugs shoulders and tells you to get on with it.

 

[westward10]

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 busbar

Does this isolator incorporate fuses.

 

[Lintay]

Does this isolator incorporate fuses.

No.its a CED SD 100

 

[Lintay]

Sorry yes it does

View attachment 35550

View attachment 35551

 

[westward10]

Not sure it does that part no comes up as a switch disconnector, a switch fuse disconnector is CED SF100. Look inside and post a pic.

 

[Lintay]

Does the dist- board need an isolator before it?

 

[Darkwood]

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 busbar

The expansion kit is fully insulated and allows for total isolation and access to the circuits without risk, you won't be even taking the lower cover off where the tails connect, I really haven't got a clue where he gets his ideas from but switching the main switch on most boards is often acceptible before removing the cover even though the tails remain live, you should know been domestic, when was the last time you removed a service fuse so you could open the consumer unit up?..Sounds like you have made (with our help) a very good suggestion and he is trying to justify poor design and wasted costs to save face by saying without any regularity backup that the dist board need external isolation after the busbar.

 

[Lintay]

Not sure it does that part no comes up as a switch disconnector, a switch fuse disconnector is CED SF100. Look inside and post a pic.

View attachment 35552

 

[Darkwood]

If as you say the fuses protecting the busbar are only 100amp then connect straight to your 125 switch disconnector in your DB, if room has been made to upgrade the system ie its all designed with 200amp rated equipment and busbar feed but the fuses have been derated then I suggest fitting a 100amp expansion kit mccb incomer, the separate isolator need not be used in any of the cases and is a waste of time, space and money.

 

[Lintay]

View attachment 35552[
So could I just use this switch with no 100amp isolator or do I have to use an mccb thx

View attachment 35553

 

[Lintay]

View attachment 35553

Looks like there 300amp

View attachment 35554