A rooftop fan unit provides the fresh air intake for an exhaust fan in a restaurant. It is also a swamp cooler. I need to wire the 1 HP fan motor and a small water pump with a cord and plug. They are both located inside the evaporative cooling compartment. Have any of you wired one of these? Where do I locate the connections? Inside the compartment? Outside on the unit or do I need to provide a seperate support. bob
From your description, it sounds like a regular swamp cooler, but with a larger motor. Most swampers have receptacles in the upper part, next to one corner. This is wired from the outside of the unit using a slb and conduit down thru the roof, into attic space. Then depending on type of wiring there, you either continue the conduit into a jbox, or change over to an approved type of raceway.
The two loads (motor & pump) just plug into the receptacles.
Using a 1 hp motor, if used at 120v, will most likely require a 30 amp plug, as the flc from the codebook is 16 amps, and when you increase that by 125%, you get 20amps. You might get by with a 20 amp circuit, but probably not. Check the nameplate for additional information to properly size the wiring & protection. You might be able to downsize this equipment if the motor can be wired 240v.
I wouldn't hardwire either of these, as that takes away your ability to disconnect them, when servicing them.
Bob, Evaporative coolers (swamp) are the norm here in Tucson and I guess I've wired a few. We use a Midwest box which has a 4 wire motor receptacle for the 2 speed motor with a time delay Fusestat for each speed. It also has a standard duplex for the pump protected by a 1.25 to 1.6 amp fusestat. We mount the Midwest box on a stand and feed it from below with Emt. Then we run cords and plugs into the cooler and connect them to the coolers interior J box which has rubber receptacles for the motor and pump. I have never seen a 120V unit on a circuit bigger than 20 amps, even some of the 10,000 CFM units which are 1-1/3HP. However, many of the larger units are run on 240V. Pumps are available as well that run on 240. The Midwest boxes have been required by city code for more than twenty years after many fires from unprotected motors and pumps as most people run them 24/7 all summer even when they are not home. After many times being helped on this forum I am thrilled to be able to make a worthwhile contribution. Brian in Sunny Arizona
Re: Evaporative cooler#28225 08/16/0306:07 AM08/16/0306:07 AM
Zapped, No, they're not the same. See www.rawtimes.com/jrellis/swamp.html elecbob, If this is the exhaust/make up air for the kitchen vent hood, also be prepared to interlock it with the vent hood's fire extinguisher (ansul) system. Most easily accomplished using electrically held relays. (check with local AHJ, usually the fire inspector)...S
Re: Evaporative cooler#28227 08/16/0310:26 AM08/16/0310:26 AM
The motor nameplate says 14 amps FLA at 120 volts. I installed controllers for the intake fan (that doubles as a swamp cooler) and the exhaust hood fan (8.7 amps at 120/208 V-3 phase) next to the CB panel. I use the N.O. auxikkary contacts on the exhaust controller to energize the intake cooler. Flipping a switch energizes the coil on the exhast controller. I built an 18" wide by 48" tall "wall" out of treated wood next to the swamp cooler. All that was in the cooler was a single speed motor and a small sump pump with a cord. I ran 1/2" EMT from an outdoor box with a disconnect mounted on the wall through the case of the cooler then adapted to 1/2" flex to the motor. I ran #10 wire for the cooler motor and installed a 20 amp breaker and #12 wire for the exhaust fan. When the fire supression system is installed on Wednesday I will figure out how to install the interconnect that kills the intake fan in the event of a fire. I drilled a hole in the cooler case to bring out the cord on the sump pump and I will plug it into a GFI I will mount on the wall. What concerned me about this puppy is that the inside of the cooler is often wetter than the outside enviroment. Any kind of a plug inside the cabinet seems unwise. I am not looking foreword to terminating the #10 in the tiny motor connection compartment. Thanks for all your help guys. Think this will work? bob
You are not required to run 10 AWG for this motor. Table 430.148 lists this 1 HP motor at 16 amps add the 25% for motor loads [430.22(A)] and you get a 20 amp load, 14 AWG at 60C is rated 20 amps [310.16] and you will still be able to put this 14 AWG on a 30 amp breaker [430.52].
Because this is a motor load the normal rule of 240.4(D) (15 amp breaker for 14 AWG) does not apply, look at Table 240.4(G)
Do you have motor overload protection as per section III of article 430?
[This message has been edited by iwire (edited 08-16-2003).]
Bob Badger Construction & Maintenance Electrician Massachusetts
Yes I have motor overload protection. There are heaters installed on the controller. I ran #10 cuz the distance from the panel to the panel to the motor is 80 feet and I ran the 4#12's to the ehxaust fan in the same conduit. bob
Re: Evaporative cooler#28231 08/17/0305:39 AM08/17/0305:39 AM