Have you heard of this before?

[nhfire77]

I was asked by a fire suppression company I normally do work for to swap out the control head wiring for a system they recently worked on. Just the control head was replaced. It was a pyrochem, your normal restaurant chemical system. It has a normal SPDT microswitch.

I found the original set up to be Normally open, with 120 Volts on it. No fire alarm interface (this place is old). The J box was labeled which panel the unit was fed from. Found it, confirmed it was the correct circuit.


Now from my previous experience with these systems, there is normally two SPDT switches in each control head. One for the fire alarm, one to shut off the "make up air" fan (wrong term?) and sometimes the hood lights. I am referring to the fan that pulls air into the hood. You want the exhaust fan to keep running (or so I am told from the hood guys here in MA.)

Normally, the fan will come back on after you release the microswitch or there is a reset switch for a shunt type device, somewhere near the kitchen door.

Last thing to do is test the switch manually. OK, I do. The kitchen gets quite. Too quiet, I think to myself, but I let go of the switch, and nothing. check for voltage at the hood control head, nothing...Check the breaker, not tripped. The Panel is a MLO, so I don't see what happened. I open up the panel and find there is no power on the breaker. Then, NO power in the whole thing, or the panel next to it. Both fed from the same feeders.

I end up finding a 225 Amp Shunt Switch in the main electrical closet. The hood system trips the shunt. The shunt kills EVERYTHING in the kitchen except the lights. It even kills the power for a Walk in refer/freezer built into the kitchen area. Its been this way for more than 20 years. No one at the place new about this, until now.

I found this to be a bit much, anyone else?

 

[mcclary's electrical]

I was asked by a fire suppression company I normally do work for to swap out the control head wiring for a system they recently worked on. Just the control head was replaced. It was a pyrochem, your normal restaurant chemical system. It has a normal SPDT microswitch.

I found the original set up to be Normally open, with 120 Volts on it. No fire alarm interface (this place is old). The J box was labeled which panel the unit was fed from. Found it, confirmed it was the correct circuit.


Now from my previous experience with these systems, there is normally two SPDT switches in each control head. One for the fire alarm, one to shut off the "make up air" fan (wrong term?) and sometimes the hood lights. I am referring to the fan that pulls air into the hood. You want the exhaust fan to keep running (or so I am told from the hood guys here in MA.)

Normally, the fan will come back on after you release the microswitch or there is a reset switch for a shunt type device, somewhere near the kitchen door.

Last thing to do is test the switch manually. OK, I do. The kitchen gets quite. Too quiet, I think to myself, but I let go of the switch, and nothing. check for voltage at the hood control head, nothing...Check the breaker, not tripped. The Panel is a MLO, so I don't see what happened. I open up the panel and find there is no power on the breaker. Then, NO power in the whole thing, or the panel next to it. Both fed from the same feeders.

I end up finding a 225 Amp Shunt Switch in the main electrical closet. The hood system trips the shunt. The shunt kills EVERYTHING in the kitchen except the lights. It even kills the power for a Walk in refer/freezer built into the kitchen area. Its been this way for more than 20 years. No one at the place new about this, until now.

I found this to be a bit much, anyone else?

Technically, it only needs to kill everything under the hood,so yes,it's a bit overkill.

 

[LarryFine]

I found this to be a bit much, anyone else?

I've done plenty of suppression system refits and upgrades. Normally, everything electrical and gas under the hood must shut down, including the hood lights and make-up air.

The exhaust blower must turn on or stay on. If the exhaust is also supplied by this panel(s), you'll need to find another way to supply it, plus a horn/strobe if you need to add one.

I once did a deli in a large grocery store that had a 400a 3ph panel in the kitchen, the main being a shunt-trip. I tapped the incoming lines for a panel for the exhaust and horn/strobe.

If they want you to just re-wire the new microswitch(es) in place of the old one(s), and there won't be a system inspection/test, then just do it. Otherwise, ask the inspector first.

 

[jes25]

I've done plenty of suppression system refits and upgrades. Normally, everything electrical and gas under the hood must shut down, including the hood lights and make-up air.

The exhaust blower must turn on or stay on.

I am working on a range upgrade in a church kitchen now. I am planning on shutting off the hood along with the range when the system goes off or the EPO is pushed. I am talking about the fan that exhausts air while cooking directly over the range. Is this wrong?

There are no inspections on the job and I'm doing it for my employer who agreed with me that it should shut off. I was thinking the fire would be sucked up the duct work if left on.

 

[LarryFine]

I was thinking the fire would be sucked up the duct work if left on.

That's not a bad thing, it's exactly what should happen, to the smoke and the fire. Exhaust ducting is a much heavier gauge than HVAC duct, and the joints are welded.

Isn't there also a fire suppression/extinguishing system with a tank, piping, and nozzles? Isn't that what triggers the electrical part of the system via microswitches?

With a system trip, the exhaust must turn or stay on, the make-up must turn or stay off, the lights and anything electrical or gas must shut down, and an alarm sound.

In addition, when the exhaust fan is manually shut off, the gas must shut off, unless there is a thermostat in the top of the hood that activates the exhaust automatically.

 

[nhfire77]

Technically, it only needs to kill everything under the hood,so yes,it's a bit overkill.

Its shunting things that aren't even in the room, I found it to be a lazy design, and it shuts off the exhaust fan, which is the worst part. (i got make up and exhaust fan confused in my first post)

I am sure that the shunt system as is was inspected, so it was locally approved, at one time. No one will even entertain the idea of upgrades. This facility has three kitchens the same size, they are only using this one. They would relocate to one of the other ones before its fixed, sad but true.

 

[LarryFine]

They may face similar issues in the others.

I agree with you, but you can only do what you can do.

The other equipment was probably added over time.

 

[gadfly56]

With a system trip, the exhaust must turn or stay on, the make-up must turn or stay off, the lights and anything electrical or gas must shut down, and an alarm sound.

Exhaust on or off is a local code requirement. All wet chem manufacturers systems are listed for exhaust on or off.

 

[GeorgeW]

Have you heard of this before

Have you heard of this before

I have done fire alarm systems work interfaced with hood systems. The only things required to shut down upon activation of the suppression system were the intake fan, and the cooking equipment.
I beleive I used a gator relay to interface the F.A. system with the fire supression system, so that when the suppression system was activated, it activated the gator relay, shut down the intake fan and killed power to the gas valve. The inspector passed it.

 

[dmagyar]

Shunt trip for ansul unit

Shunt trip for ansul unit

I answered a trouble call from a local restaurant. Lights were off under the exhaust hood, cook couldn't see. I found out that this particular system had shunted out during a short power outage. The only thing that went off were the under-hood lighting. Gas, exhaust everything else was working fine. I reset the breaker which had the shunt trip, lights came back on. I had several conversations with the local fire marshall about why the gas solenoid wasn't connected to the system. He didn't have an answer but was changing his directives to his inspectors. It didn't make sense at the time that the exhaust would stay on but now does. Another thing that really got me was the conduit for the system above the ceiling, it was horrendous, no support for a 16x16x8 junction box laying on top of a wall, 2" conduit laying over only held up by connectors. Another low bid getting the job.

 

[RETRAINDAILY]

the last one I set up had a shunt trip that shutdown all panels serving all kitchen equipment.

 

[nhfire77]

What state was that in? Was it a local requirement?

 

[masterinbama]

Its shunting things that aren't even in the room, I found it to be a lazy design, and it shuts off the exhaust fan, which is the worst part. (i got make up and exhaust fan confused in my first post)

Things were likely added to this panel, by people who didn't know what the shunt was for.

 

[nhfire77]

Its shunting things that aren't even in the room, I found it to be a lazy design, and it shuts off the exhaust fan, which is the worst part. (i got make up and exhaust fan confused in my first post)

Things were likely added to this panel, by people who didn't know what the shunt was for.

It did not appear that anything was added to either Panels since the original install. All the breakers seemed to be the same age/condition (old) except two or three SP breakers at the bottom, that were obviously newer. Unless the guy that added it did a really really neat job, but, if you saw the rest of this place, you would know , nothing added since the original install was neat.

 

[fishin' electrician]

It did not appear that anything was added to either Panels since the original install. All the breakers seemed to be the same age/condition (old) except two or three SP breakers at the bottom, that were obviously newer. Unless the guy that added it did a really really neat job, but, if you saw the rest of this place, you would know , nothing added since the original install was neat.

Not doubting what you saw or concluded from what you saw, but more often than not the gear for these types of jobs initially come through full of breakers whether they are needed or not.

 

[nhfire77]

Not doubting what you saw or concluded from what you saw, but more often than not the gear for these types of jobs initially come through full of breakers whether they are needed or not.

True, I cannot confirm or deny. There were mostly 2 and 3 pole breakers feeding large pieces of cooking equipment, that appeared old. I am having trouble seeing two 42 space MLO panels being installed with a large feeder from a shunt, with the possibility of expansion. It appeared to be a properly sized OCPD for the current load. That is a huge assumption on my part. This isn't the kind of place where that much forethought would go into it.

I see your point though.