ReplyIs there presently a service switch in the boxes for the fans ?
Professional Member
My fire department inspector says we need a switch inside the walk in freezers to kill the evaporator fans in case someone gets trapped inside.
These are normal pump down type systems. One evaporator is 120 volt but the other one is 220 volt.
I assume I'd want to kill the liquid line solenoid too. Not too sure if I need a mushroom head push/pull switch with low voltage wiring leading to a contactor. Maybe a line voltage toggle switch is good enough?
Global Moderator
Is there presently a service switch in the boxes for the fans ?
Professional Member
No. The 120 volt one just plugs into a ceiling mounted receptacle. The 208 volt one is all hardwired.
Kinda looking to find out if NEMA 4X and/or low voltage is required.
Global Moderator
I would ask the local electrical inspector what he wants. I would also think that code would require a disconnect within sight off the evaporator.
Professional Member
How about a double gang switch box with a single and double pole switch and a bunch of liquidtite.
You could do a second set for closing LLSV or perhaps just the valves, it not the fans that are a problem were someone to be trapped, they create heat and a bunch of noise
Professional Member*
I have never heard of a fire code like this, you will have to ask the fire chief what he wants to be sure. Like VTP99, though, I have heard that there is an electrical code that requires a disconnect within line of sight of any mechanical equipment. I also believe it is against electric code to have a cord and plug coming out of the cooler evaporator.
If you are going to shut off the fans, it is strongly recommended to also have the solenoid shut off at the same time. Otherwise, you run the risk of slugging the compressor.
With a standard 115v walk-in cooler, I usually set them up with a single pole toggle switch to break the hot wire that feeds the fans and thermostat. If by some chance, the fans and the solenoid are on separate circuits, or the wiring is too hard to trace out, you can use a double pole switch wired in series with the thermostat on one pole, and with the hot wire to the fans on the other pole.
With a 230v Freezer, it gets more complicated. Since power to the fans and defrost heater usually come from the defrost timer, it is usually best to wire the disconnect to break both hots to the defrost control. Hopefully, if you do this, your solenoid will shut off too. Otherwise, if you just break 2 hot wires right near the evaporator to get the fans and solenoid to shut off, the heaters will still become energized when it goes into defrost, and that could be dangerous to an unknowing service guy.
Professional Member*
show him the door......
SDC/Educational/Membership Committee*
As JWB alluded to, the safety release mechanism on the door latch should be all the fire department needs.Originally Posted by Russ57
While I've never had this brought up by a fire inspector, the disconnect requirement that VTP99 mentioned has come up a number of times with electrical inspectors. I don't know the chapter and verse of it all, but I believe there's a section in the NEC which allows for no disconnecting means for such installations. Perhaps Wolfdog knows of it.
Think about this a moment. Do you know of any supermarket where there are disconnects for each case? I thought not.
Professional Member*
The 115 volt cord is the drain heater, I'd bet.
Maybe the fireman should leave a fire ax in there??
Professional Member
Just put a single pole switch to break the "4" terminal coming from the timer to the evaporator. That should kill fans and solenoid.
Professional Member*
Please don't do the above advice if you have a 230v device. You really need to break both hots, otherwise you could hurt or kill someone.
Professional Member
http://www.modularm.com/door-alarms-...oor-alarms.php
This guy does exactly what you're looking for and more.
They're a bit pricey, but it will get the fire guy off your back.
Professional Member
Believe it or not, more and more cases are coming from manufacturers with service switches for the fansThink about this a moment. Do you know of any supermarket where there are disconnects for each case? I thought not.
Barker and Hill/Phoenix are leading the charge. Well, when they can get the switches wired properly....
Professional Member
I'm going to have to get up there and see what all I have. It turns out both evaporators are hard wired 208. Best I can remember, when I installed A419's in them, one had to be wired for 208 but the other was just 120 (to the LL solenoid).
I know I could do a lot of things, like involving the time clock and removing the X terminal so the fans don't start once it warms up. However I'm not crazy about that. Plus one freezer has the time clock and contactor back at the mechanical room and one has it on the outside door of the freezer.
Whatever I do needs to be fairly quick as I doubt I can get them to shut down and empty the box. It is looking like anything I do needs to be waterproof. For safety reasons I'm leaning more and more to a stainless NEMA 3R/4X safety switch and killing ALL power. Gonna suck if I have one 208 circuit for the fans, another for the defrost heaters, and another 120 circuit for the LL solenoid. Mostly piped in ridgid and aluminum bell boxes from the 70's and the stuff doesn't come apart easy! At that point changing the breakers to shunt trips and hoping I can pull a pair of wires in the existing conduits is probably easier.
Does seems a little strange that the fire department is requesting it. This is someone who comes by once a year and typically makes sure fire doors are positive latching and such. Must be some new OSHA requirement or something. I know a boiler inspector recently made me install such a switch outside the boiler room door. Like this stuff is really going to help if you are locked in a freezer overnight or the boiler blows up
Anyhow, just thought maybe some of you guys had dealt with this already and knew a nice quick, cheap, and easy way to do it.
Professional Member*
Maybe you could mount 24v contactors and a transformer in a box in the mechanical room near the breaker panels and wire them up to break power before it goes to the time clocks. Then you could run thermostat wire to a single pole switch in the freezers.
If one of your solenoids is 110v, that might throw a wrench in things, though.
I can appreciate what you mean by in needs to be done quickly when you have a 0 degree box to work in, and you are from Miami.
By the way, Removing the "x" terminal wont do anything, except make the defrost cycle take longer. Good luck!
Professional Member*
There is a difference between "should" and "must". Should means he thinks its a good idea, not really up to him though. Must means there is a code or regulation on it. Get clarification before you spend money. 24 years in this trade and 11 years in the fire service, 5 of those as a chief, and I have never heard this. Code requires the door safety and that's all I know of.
Professional Member
Yes, I am debating fighting it. But we have a great relationhip with the inspector and I'd like to keep it like that.
A switch in series with the "4" terminal and the loads is the quick and dirty way. However it has me running a couple hundred feet of conduit and might make someone think it is safe to work on the evaporator....which it wouldn't be!!!
Professional Member*
If the 230V power was supplied via contactors at the outdoor unit (fans/defrost heaters) - and depending upon how, exactly, the control wiring is configured.....I wouldn't have a problem breaking one leg of the control power via a single pole fan switch. Should kill one side of both contactors as well as one leg to the LLSV.
"The problem is the average person isn’t tuned in to lifelong learning, or going to seminars and so forth. If the information is not on television, and it’s not in the movies they watch, and it’s not in the few books that they buy, they don’t get it" - Jack Canfield
Professional Member
What is needed is a either a push rod or if the door is locked an internal way of forcing it open
I know when i go into a beer cooler especially that has a padlock I take the padlock with me inside
shutting the fans off or solenoid does nothing for the person locked inside
how many cases, outside of hollywood, has this happened
Pro-Rep Member
I think that just shutting off fans may not be a good thing for the system. The compressor is bound to be very unhappy sooner or later! Of course, once the compressor breaks, the room will get warmer and the person locked inside will be OK!
There are modern evaporator controls out there that will shut the entire system down with a simple dry contact switch. The fans, heaters AND compressor will all shut down. The same switch input can also cause an alarm (light, siren) locally and an email or text sent out. Safety, alarm and notification all in one package.
In an infinite universe, not only are all things possible, all things are necessary
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