Designing choices reasons

[i=p/u]

We doing a high school canteen at moment and guy in charge doing install said thy waiting for panel to be delivered and fitted. They could get away with with say 2 x 12 way tp-n boards so why get a panel that fills a full cupboard ??? Isit for fault current . Just want o know why they would choose a panel.

 

[i=p/u]

Would it biggest rating of main switch of tp-n board. Maybe this reason..

 

[ipf]

It will be designed to do what is required, although designers have been known to go a bit over the top.
Provisions for a High School canteen will all depend on the kitchen equipment being installed, quite a heavy load, generally.
Without knowing the details, impossible to give an accurate answer.

 

[atm84]

Size of breakers required maybe. is the panel board feeding sub mains or heavy loaded equipment?. A panel board can be fitted with 100amp or greater breakers that are also adjustable. A standard 12 way tp-n board would only be able to fit 63amp breakers max.

 

[i=p/u]

Makes sense already , but can't see anything being over 63A 3 phase .. But could come down to main switch. Bu

 

[atm84]

Yes main switch in a 12 way tp-n would either be 125 amp or 250amp. Not sure how big they can go for a panel board. Ask your boss at work or another one of the lads. Let us know when you find out.

 

[ipf]

Start throwing a few 63amp 3 phase supplies feeding cooking ranges and the load is soon going to be way too high for a basic TPN DB main switch.
At peak times, the odds are that everything will be in use at the same time. No diversity and total load required.
An MCCB panelboard has probably been specified, as a result.

 

[Marvo]

Prospective fault current could also be a reason for a larger distribution board.

 

[Jay Sparks]

A main switch is just that.....a main switch...it will not trip for overload!!!!......unless Im reading this wrong??? A main switch is rated at the supply it can safely disconnect!!!

I could be missreading this due to the amount of alcohol ive consumed tonight..lol

 

[Knobhead]

An main (isolating) switch is not rated for it’s disconnect capacity, it is an off load switch.

As to why a larger board has been specified you have to ask the designer. It could be be any of the above reasons. Do you know what the supply rating is? That is the deciding factor. It governs the fault level and therefore the downstream protection.

 

[Engineer54]

Start throwing a few 63amp 3 phase supplies feeding cooking ranges and the load is soon going to be way too high for a basic TPN DB main switch.
At peak times, the odds are that everything will be in use at the same time. No diversity and total load required.
An MCCB panelboard has probably been specified, as a result.

Why would you think that no diversity is allowed?? I've come across very, very few installations where you wouldn't be able to apply some form of diversity....

In all probability, a panel board has been specified, in order to accommodate both MCCB's and MCB's, along with one or more of the other above suggestions, but not knowing the installations requirements, like all the other suggestions, this is just another maybe assumption!!

 

[ipf]

Why would you think that no diversity is allowed?? I've come across very, very few installations where you wouldn't be able to apply some form of diversity....

In all probability, a panel board has been specified, in order to accommodate both MCCB's and MCB's, along with one or more of the other above suggestions, but not knowing the installations requirements, like all the other suggestions, this is just another maybe assumption!!

Spot on with the panel board and pretty obvious that there are unknown factors.

Regarding the diversity, try a major school kitchen any morning of a working week. It is hectic and everything is operating. Did some work on one last year (6mm 4 core pyro blown) with 5 3ph ranges all operating on full, 2 extras (one down) on standby and then there's the ovens, warmers, etc. It's that 3 or 4 hour period. 400amp MCCB.
Them kids want their din dins. lol.

 

[Knobhead]

We lost the supply to one of the works canteens. Sod the kids want their dindins, I’d got Mavis wielding a bloody great soup ladle backed up by a load of hairy arsed quarry men after my blood. The fact ⅓ of the plant was down cut no ice with them! Try explaining to a very irate Mavis that the 11KV had tripped on U/V. I got earache off her for months.

Her revenge, “porridge” she made it plain so people could put what they wanted in it, she laced it with sugar knowing only my mate and I had it with salt. Everyone was in on the act, all waiting for us to take that first spoonful! :ack2: :ack2:

 

[atm84]

Any update then?

 

[Andy78]

Any update then?

I assume she is still making the porridge the same way to this day.