Hello. what is the purpose of shunt trip breakers in a commercial kitchen hood control panel? I have built over 30 controld panels for kitchen hoods . Never have useda shunt trip trip breaker ever . The contol panels are controlled by the ansul micro switch. Operation is cookline outlets energized non dependent if control box is on or off. Push maintaned pushbutton energizes contactors for ex fan and make up air fan . Ansul switch is pulled make up air contactor opens ex fan contactor stays on and cookline outlets are no longer energized . ansul switch returned to other position everything goes back as i first described . Never have had any of the boxes i have built have any problems . Ever city inspector has passed all my boxes with no problem . For what reason would you want to trip the breaker to perform the same function ? then have to manually reset it . It makes zero sense to me . Can someone eleborate why a shunt trip breaker would be used in this example . And or why or what shunt trip breakers offer in any circuit . i was under impression the breakers are built like contactors . how many trip cycles could a breaker endure before failure ? contactors are built to open and close heavy amp loads thousands of times . Why use a breaker for this purpose ?
Shunt trip breakers in a commercial kitchen hood control panel
- Thread starter bneck
- Start date
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Only to avoid having contactors being continuously energized.
Manual resetting is only necessary when testing or an actual fire.
Only an electrical gas valve needs to have power interrupted daily.
Manual resetting is only necessary when testing or an actual fire.
Only an electrical gas valve needs to have power interrupted daily.
- Location
- Illinois
- Occupation
- retired electrician
UL 489, the standard for circuit breakers, requires that breakers of 100 amps of less pass a 10,000 cycle test, with 4,000 cycles at no load and 6,000 cycles at the full rated load of the breaker. The number of testing cycles for listed breakers goes down as the breaker rating goes up.
| Frame Size in Amperes | Full Load Operations | No Load Operations |
| 0-100 | 6,000 | 4,000 |
| 101-225 | 4,000 | 4,000 |
| 226-600 | 1,000 | 5,000 |
| 601-800 | 500 | 3,000 |
| 801-2500 | 500 | 2,000 |
| 2501-4000 | 400 | 1,000 |
Circuit breakers are not tested until they fail, so the maximum number of operations is not known.
Environmental factors affect the life of a breaker, so the number of test operations in the table should not be interpreted as a guaranteed number in actual use.
MTW
Senior Member
- Location
- SE Michigan
It can offer a lot of simplicity and reliability when used with a breaker panel equipped with a shunt trip main breaker, on a new build install.
You feed all of the under hood equipment that requires shutdown from that panel, including the air make up and electric gas valve, along with the cooking equipment.
The only things not fed from that panel is the fire system, reset relay, strobe horn annunciator and the exhaust system. The exhaust system needs a SPDT relay in addition to it's normal manual on/off control circuit to energize it automatically in the case of a fire. Regardless if the manual control is on or off. The shunt trip coil is not intended to be energized continuously, so it should be fed from this panel as well, to prevent shunt trip coil burnout, when the system is activated.
This allows equipment to be added or changed to the lineup without modifying anything in the contactor panel or wiring and allows the fire trip signal to come from a fire control head micro switch, manual pull station, as well as a building fire alarm panel.
To reset the system, you reset the fire control head, reset relay and the main shunt trip breaker. something that the fire system contractor should be well familiar with, and be doing regularly on a schedule.
It's not that a panel full of contactors continuously energized don't work, it mainly depends on the circumstances of the site requirements, and how often things may need to be altered or upgraded.
