Wiring a Pizzeria have a few questions about shunting an oven

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TNeighbarger

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Hi all this is my first post on the forum so thank you in advance. My question is this...

I landed a job that is roughing in a small pizzeria near downtown Los Angeles and I need to pull 200 amps of 208/120v 3 phase into the suite off of the 240/120v 3 phase gear. I know that there is a high leg coming off of the transformer but the previous electrical plans only called for pulling in a single phase into each suite. So I will have to tap the high leg and install a 3 pole breaker. My question is should I use a split bus panel? There is not much lighting other then what is in the back of house. 2nd question is how to shunt the oven they want to use. It is a electric oven that has 2 decks, each deck draws 46.8 amps. Each deck on the oven is fitted with its own power supply cord. Is there a way to shunt both decks of this oven from a single location. Or am I going to have to shunt each deck individually? The reason for shunting the oven is because of the hood and ansul system. Thank you
 
I doubt you actually have a 120/240 3-ph main in the building. It's probably 120/208. I think split-bus panels are illegal nowadays.

Shunting the oven is done with a shunt-trip breaker. Power is controlled by the fire suppression system to said breaker. Run the power through the Ansul system to the two shunt breakers supplying the ovens. If the Ansul system is triggered, it sends power to the shunt-trip breakers causing them to open.
 
I doubt you actually have a 120/240 3-ph main in the building. It's probably 120/208. I think split-bus panels are illegal nowadays.

Shunting the oven is done with a shunt-trip breaker. Power is controlled by the fire suppression system to said breaker. Run the power through the Ansul system to the two shunt breakers supplying the ovens. If the Ansul system is triggered, it sends power to the shunt-trip breakers causing them to open.


the main reads as follows:
section amps 800
supply amps 800
volts 240/120
3 phase
4 wire

I am just telling you the information i was able to gather via pictures. I will be down there this coming Monday to open the gear up and throw a meter on it. Thank you for clearing the ansul situation for me, I was making it more complicated than it needed to be. I've installed shunts on other equipment but nothing where I had to different supply connections. Thank you 480sparky
 
the main reads as follows:
section amps 800
supply amps 800
volts 240/120
3 phase
4 wire

I am just telling you the information i was able to gather via pictures. I will be down there this coming Monday to open the gear up and throw a meter on it. Thank you for clearing the ansul situation for me, I was making it more complicated than it needed to be. I've installed shunts on other equipment but nothing where I had to different supply connections. Thank you 480sparky

120/240 is the maximum voltage. Take a meter and check it. 99.99999% probability it's 120/208. If it actually is a high-leg delta, and each bay is only to be supplied with single-phase, then 2/3 of the bays will have half their panels with a single-phase high-leg. Not a very wise design choice.

Not sure why you thought a split-bus would help.
 
I wasn't aware that split bus systems were no longer allowed. My thinking on the split bus system would be to separate the equipment loads from the lighting loads.
 
For what purpose?
To prevent any issues with lighting equipment i.e. led drivers and room controllers during the equipment start up. Is it possible to get dimming or strobing from lighting when equipment starts and has a large draw on the phases in the panel? That was my only thinking on why I would consider a split bus panel. I am under the impression that the lights mainly because all of them now are led super sensitive to power draws.
 
To prevent any issues with lighting equipment i.e. led drivers and room controllers during the equipment start up. Is it possible to get dimming or strobing from lighting when equipment starts and has a large draw on the phases in the panel? That was my only thinking on why I would consider a split bus panel. I am under the impression that the lights mainly because all of them now are led super sensitive to power draws.

If it's due to a transient voltage drop on the supply end caused by heavy start-up loads, it won't matter whether you use a split-bus or not. It's a matter of Ohms' Law.
 
If you do have a high leg delta service, note that you can't pull 120/208 off it without a transformer.
Would that be dependent on whether it is open high leg delta or closed high leg delta? And I am assuming i will be able to find out when I put my meter on it Monday. I just read up on the open or closed high leg delta thread and honestly I am not sure if I am more confused now than before. ;)
 
Would that be dependent on whether it is open high leg delta or closed high leg delta? And I am assuming i will be able to find out when I put my meter on it Monday. I just read up on the open or closed high leg delta thread and honestly I am not sure if I am more confused now than before. ;)
The unloaded voltages should be the same on an open and a closed high leg delta.
What is different is the variation in voltage on the high leg under three phase loads. (Or single phase loads using the high leg and one of the other legs or the neutral.
The open delta has much worse voltage regulation under load. (The behavior on the A-N-C circuit with respect to loads only on that circuit should be identical between the two.)
 
TN, welcome to the forum.

You can not get 208/120 from 240/120 without a transformer. If the plan is, as you said, to bring only a 1ph supply into each bay, you won't be using the high leg at all. Make sure you understand that, except for the high leg, your supply is identical to a typical 120/240v 1ph supply.

The high leg is 240v to either of the other lines, so you can use it to supply a 240v 3ph load or a 240v 1ph load, but it can not be used to supply a 120/240v 1ph load. If your ovens are 240v only, and you will have any 3ph loads in the store, I recommend using a separate 3ph panel.

I would also place each oven section on the high leg, one between L1 and the high leg, and the other between L2 and the high leg. That lessens the loading of the two 120v-to-neutral lines and balances the three lines a bit. Let us know if you need any help with the fire system wiring.
 
TN, welcome to the forum.

You can not get 208/120 from 240/120 without a transformer. If the plan is, as you said, to bring only a 1ph supply into each bay, you won't be using the high leg at all. Make sure you understand that, except for the high leg, your supply is identical to a typical 120/240v 1ph supply.

The high leg is 240v to either of the other lines, so you can use it to supply a 240v 3ph load or a 240v 1ph load, but it can not be used to supply a 120/240v 1ph load. If your ovens are 240v only, and you will have any 3ph loads in the store, I recommend using a separate 3ph panel.

I would also place each oven section on the high leg, one between L1 and the high leg, and the other between L2 and the high leg. That lessens the loading of the two 120v-to-neutral lines and balances the three lines a bit. Let us know if you need any help with the fire system wiring.
The oven can come in different variations depending on how it is ordered. I spoke to the rep who is supplying the oven and he said that each deck of this oven will draw 100amps single phase and there are 2 decks. I would like to get it on 3 phase so it will not down the amperage to 60 per deck. I can get the oven wired for 240v 3 phase or 208v 3 phase. The main in the electrical room is a 800amp 240/120v 3 phase 4 wire system. There is only A B and N fed into the sweet on a 200 amp breaker. From what I have put together is that I can get my 3 phases out of the gear but in a high legged 4-wire delta which gives you 120, 240, and 208. This system is grounded in the middle of A and C phase?
 
Given the choice, I recommend the 240v 3ph option. Again, I suggest a separate 3ph panel or disconnect for the oven. You can not use the high-leg 208v to neutral to supply anything, by the way.

Suite, not sweet.
 
........ There is only A B and N fed into the sweet on a 200 amp breaker. From what I have put together is that I can get my 3 phases out of the gear ..............

If you've only got single-phase to the bay's panel, you need a phase converter to get 3-phase out of it.
 
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