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

[westward10]

Yes you need to know the fuse sizes in the switch disconnector for the busbar because if they are 100A this is all unnecessary. If they are 200A then the 125A, 60947-3 switch and the supply conductors need circuit protection, I would guess a 100A 60947-2 main switch at the board would break the bank. Your only option is to use that switch although I am confused by its part no but it looks like the solid links could be replaced with fuses. Shame he opted for that cheap nasty option. You need to go back to square one and confirm the fuses protecting the busbar and remember a 200A switch doesn't necessarily mean 200A fuses.

 

[Darkwood]

I already answered that Lintay, it depends on the busbar overload protection and that its designed to be 100amp without room for upgrade then yes its totally fine to tail direct to your switch disconnector.

PS the last pic showing the 300amp isolator for the busbar does not tell us what fuses are fitted in it but I suspect they are bigger than 100amps, your boss has thus designed it wrong, picked an isolator instead of a switch fuse and made a pigs ear of it all, get a mccb expansion kit for the board, tail it as required to the size you choose and job done, and tell your boss from me that he really shouldn't be taking on work like this if he doesn't understand the regulations around it, ask him what rating the fuses are in the busbar switch/fuse, if he doesn't know then he hasn't spec'd the job properly.

 

[westward10]

Are you 100% certain that is the main switch, I assume that isn't at the main intake.

 

[Lintay]

Are you 100% certain that is the main switch, I assume that isn't at the main intake.

That 300amp main switch is fed from a substation other end of the warehouse

 

[Darkwood]

@Lintay

Now we have eventually been given the correct info all but the busbar overload protection size, the info we have provided does explain how this should be done given different circumstances of the busbar fusing size.
There is really nothing more that we can add other than to tell your boss that it's beyond your experience and you need assistance, I would also question where the experienced assistance you need would come from because it sounds like your boss also doesn't understand how to design this kind of job let alone the regulations around it so IMHO he shouldn't be taking on such work, usually for me the hardest part to this work is sourcing busbar clamps to suit the old board as under no circumstance should you double up on existing ones, I also assume you haven't been supplied with heatshrink sleeving for the terminations either all of which is how it should be done professionally.

 

[westward10]

Just a final shot, that supply cable isn't very big not rated at 300A anyway so I suspect you need to look at the source end to confirm. Probably only 63A

 

[Lintay]

Thx guys my boss had agreed to get rid of the isolator and he's ordered a 100 amp mccb kit which he's still adamant 25 mm tails will be ok?
Where the existing boards were that we ripped out we will be using there old points to connect to the bus bar using bolts and washers.shojld I use 8 mm brass bolts?
Thx again

 

[westward10]

They should be 35.0 minimum, or 25.0 BS7211.

 

[Lintay]

They should be 35.0 minimum, or 25.0 BS7211.

This expansion kit will it make the dis board longer tryed asking the wholesalers and they don't know! Thx

 

[Darkwood]

Thx guys my boss had agreed to get rid of the isolator and he's ordered a 100 amp mccb kit which he's still adamant 25 mm tails will be ok?
Where the existing boards were that we ripped out we will be using there old points to connect to the bus bar using bolts and washers.shojld I use 8 mm brass bolts?
Thx again

You really need to be asking your boss these questions as oppose to the forum, we are happy to nudge you in the right direction but a step by step guide which your asking for is somewhat abusing our good nature to help, you need to use the appropriate rated busbar clamps that are designed for that busbar system, usually they come in different ratings ie 100amp, 200amp etc, we cannot possible tell you if using the existing is ok as we do not know what has been used and whether they are the official kits or not you want to re-use.
Speak to your boss, if he cannot answer or help you out here, I would politely decline to do the job, he was aware of your experience in the first place, if he drops you on such jobs without the guidance you need or the right kit to do the work then you may want to consider your future options and what you are getting yourself into here, I cannot comment on your circumstances so you may need to just bite the bullet a while and possible look for a company that is willing to support your and train you up in areas you lack experience, mistakes will be made otherwise and sometimes this may put people and property at risk without you realising.

 

[Darkwood]

This expansion kit will it make the dis board longer tryed asking the wholesalers and they don't know! Thx

You have all the info you require already posted, please help yourself out a little here, I posted a link that shows you the part no's etc of upfront switch gear and expansion kits, if you have any queries ring Scheinder tech' support team, they are very helpful and just explain your inexperience and you have a few questions, and to answer your query, Yes, by the nature of the word 'Expansion' kit, it will indeed make the board longer and needs fitting first before mounting to the framework you intend to fasten to.

You'll need to know the lug hole sizes required to bolt onto the new mccb too while your talking to them, make a list of the part no's you have too so they know exactly what you have.

 

[westward10]

If that is a Bill busbar I suspect it may have copper bars that you drill to suit.

 

[Lintay]

just wanted to say thx guys learnt loads of you if u need any domestic tips u know where I am! Thx again

 

[westward10]

just wanted to say thx guys learnt loads of you if u need any domestic tips u know where I am! Thx again

Mm I will bear it in

 

[GMES]

How long have you had the stuttering Finger Westy lol