Replies

1. 
   BillHartmann | Oct 28, 2008 12:27am | #1

   "In other words 240 x 125 = 30000 VA "

   Yes. Assuming that the load are balanced.

   You have 2 hots and a neutral that only carries the difference in currents in the 2 legs.

   So you have have 125 amps in one leg, and zero in the other,

   Or 125 amps in both legs

   Or 125 amps in one leg and 85 in the other.

   Thus when laying out the circuit you want to make sure that any heavy loads are distributed over both legs.

   Typically those would include bathroom circuits, washer circuit, kitchen counter top circuits, appliance circuits, any pumps, and any 120 volt heating circuits.

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   A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
1. 
   hanlonk | Oct 28, 2008 12:37am | #2

   Bill, You clarify and obscure at the same time.
   I'm trying to calculate a ball park power requirement for a small bakery. Any thoughts on the general calculations on panel size?
   So I add up all the amperages of my equipment and then is there a rule of thumb multiplier to get the panel main required? Obviously not all machines would ever be on at the same time.
   K

1. 
   BillHartmann | Oct 28, 2008 12:42am | #3

   There is a large section of the NEC that covers calculating loads.And there is a number of places where they put in demand factors and also where equipment CAN'T be used at the same time. And for things like electric stove they realize that all burners and the oven won't be on max at the same time, so a fraction of the load is used.But I am only familiar with the calculation for residential use. Don't have the slightest idea, nor the time, on how commercial loads are calculated..
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   A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

2. 
   junkhound | Oct 28, 2008 03:01am | #4

   ball park power requirement for a small bakery

   Commercial?  How 'small'??

   10 ovens or so??  All on at peak times??

   100KVA,  80% derate, 600A service. 

   Ya got 3 phase available?

1. 
   hanlonk | Oct 28, 2008 05:15am | #5

   Way smaller, mixers, electric fryer, refers, etc. Total ratings add up to 135 amps at 120V and another 25 amps at 240V. So your saying typical panel requirements are 80% of equipment ratings? I just need a ballpark number to screen potential rental spaces and or negotiate a service upgrade with a landlord if necessary.
   Thanks, Kevin

1. 
   Dinosaur | Oct 28, 2008 06:59am | #6

   Standard residential service is now 200 amps here--for very ordinary, non-McMansion homes and bungalows--and has been for 20+ years. 

   Residential kitchen wiring requirements are: two 20A 120V dedicated circuits at counter height for toasters, mixers, microwaves, tea kettle, etc., plus a dedicated 15A circuit for the refrigerator, and another 15A circuit serving the baseboard-level plugs. Plus 50A 240V for the electric cooker, of course. Plus 20A 240V for heat, and another 15A 120V for lighting and the hood.

   85A @ 120V + 70A @ 240V. And that's a residential kitchen.

   I do not see you running a commercial bakery on 135A unless you're planning on using an E-Z Bake Oven....

   Dinosaur

   How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....

2. 
   hanlonk | Oct 28, 2008 07:26am | #7

   I see your point. I'm talking about a small donut shop, seems like 200 Amp bare minimum, never mind if sales are rockin' and I want another fryer, and an oven for this , that or the other thing... and the beat goes on.

3. 
   maddog3 | Oct 29, 2008 03:31am | #8

   just how small how these donuts ?.

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