Small Commercial Kitchen

[RM Electric]

Hey Gents, me agaian.

In this kitchen I have:
one - 220 volt, 20 amp motor for an exhaust hood.
one - 220 volt 20 amp motor for a make up air chiller.
These two items have to work with each other, if the hood is on, the make up air must be on.
I was going to do this through a contactor, with a SP 120v switch at the hood.

But I also must shut down the make up air when the Ansul system is activated.
I was going to do this with a shunt trip breaker off of the micro switches in the Ansul system.

I also must shut down a convection oven under the hood.
I was going to do this with a shunt trip bkr, does a contactor do the same thing?

My questions are:
Do I need the shunt trip breaker? (With this item on a contactor.)
Are shunt trips more expensive than contactors?
Is there a contactor that can be turned on with one SP switch (air sytem) and shut down with a micro switch from the Ansul system?
Should I use a contactor to shut down the convection oven circuit, or stick with the shunt trip bkr?


Thank you,
Robert

 

[LarryFine]

In this kitchen I have:
one - 220 volt, 20 amp motor for an exhaust hood.
one - 220 volt 20 amp motor for a make up air chiller.
These two items have to work with each other, if the hood is on, the make up air must be on.
I was going to do this through a contactor, with a SP 120v switch at the hood.

Okay, questions again:

1. Be specific - does each motor actually require 20a, or do they just specify a 20a circuit?
1a. What is the actual load current of each?

2. When you say "...if the hood is on..." do you mean "...if the exhaust fan is on..."?

3. How are the two fans manually controlled? One switch? Two switches? Not specified?

4. How are the two fans wired? Through the switche(s) or through contactors or starters?

But I also must shut down the make up air when the Ansul system is activated.
I was going to do this with a shunt trip breaker off of the micro switches in the Ansul system.

In no particular order:

1. When the make-up air fan goes off, the exhaust should also turn on, regardless of switch position(s).

2. You also need the lights to go off?

3. A shunt-trip breaker is basically a remote-trippable breaker, and must be reset like one.

4. The Ansul switches may very well be capable of handling the fan-motor currents directly.

I also must shut down a convection oven under the hood.
I was going to do this with a shunt trip bkr, does a contactor do the same thing?

1. Again, a breaker must be reset, but a contactor can be energized and de-energized instantly.

My questions are:
Do I need the shunt trip breaker? (With this item on a contactor.)
Are shunt trips more expensive than contactors?
Is there a contactor that can be turned on with one SP switch (air sytem) and shut down with a micro switch from the Ansul system?
Should I use a contactor to shut down the convection oven circuit, or stick with the shunt trip bkr?

1. Not with a contactor.

2. Yes, they are.

3. Yes, easily.

4. The former.

 

[LarryFine]

By the way, I can easily draw you a complete diagram and what parts you'll need if you can answer these questions well.

PM me for my phone number if you would like. Offer open to anyone with a similar job, if it doesn't get out of hand.

 

[RM Electric]

answers

answers

Here are some answers

Okay, questions again:

1. Be specific - does each motor actually require 20a, or do they just specify a 20a circuit? Not nessasarily
1a. What is the actual load current of each?5.8a and 5.5a

2. When you say "...if the hood is on..." do you mean "...if the exhaust fan is on..."?yes

3. How are the two fans manually controlled? One switch? Two switches? Not specified?one switch

4. How are the two fans wired? Through the switche(s) or through contactors or starters?just to the panel for now with hopes of going into a contactor and having a switch by the exhaust fan.


In no particular order:

1. When the make-up air fan goes off, the exhaust should also turn on, regardless of switch position(s).yes

2. You also need the lights to go off?no

3. A shunt-trip breaker is basically a remote-trippable breaker, and must be reset like one. ok

4. The Ansul switches may very well be capable of handling the fan-motor currents directly.ok


1. Again, a breaker must be reset, but a contactor can be energized and de-energized instantly.ok


1. Not with a contactor.

2. Yes, they are.

3. Yes, easily.

4. The former.

 

[LarryFine]

Here are some answers

Okay, this is a simple one.

First, there's no reason both motors can't share one circuit.

Second, the micro-switches can handle the motor currents.

Third, I forgot to ask the specs on the convection oven.

V. ____ A. ____ Ph. ____.

Fourth, another question: must the fans be on when the convection oven is on?

i.e., must the oven go off even when the fans are manually turned off?

Fifth, is there an electric gas valve you need to hook up? (Ask gas plumber, or look for mechanical valve)

Oh, my bad for assuming: the fans are 1-ph, right?

Okay, here's what you'd normally do:

And, here's what you'll do instead:

Notes:

1) These show 1-pole (120v) switching. The loads can be the motors themselves, or contactors (relays), depending on the load currents. In RM's case, the two motors can be directly controlled, and can share a single 20a circuit.

1a) Your wire colors might be different, like, yellow, blue, brown, etc. Plus the second section should have the same colors, but with stripes added.

2. You can use both sections of the micro-switches to control both legs of the power, and using a 2-pole manual switch. I believe the switching does not have to be in both hot conductors, so you could use one micro-switch.

3. A contactor, sized for the oven, with a margin, can be mounted in a metal enclosure, and wired almost anywhere in its circuit. The coil voltage should match the supply voltage (240 in this case), or run a neutral for a 120v coil.

4. Before I forget, simply wire the contactor(s) in parallel with the intake fan, as it can only run in the normal position. Keep in mind that the fans must be turned on for the oven to receive power. If that's bad, let me know.

5. The oven might not need the contactor, so let me know about it. Once I get this dialed in, I can make a more exact diagram, including the extra stuff, like the contactor, the gas solenoid, etc.