Newbie needs help!

[HarleyJames]

Guys, I'm trying to wire up 2 squirrel cage fans in my shop for cooling engines for my motorcycle dynamometer. My first mistake is that I assumed the fans wouldn't pull as much amperage as they do. I ran to the hardware store and bought everything I thought I needed. I bought and pulled 2-20amp receptacles a 20 amp light switch, a 20 amp breaker and I pulled about 60 feet of 12/2AWG Romex. I used the light switch to operate the 2 receptacles. The receptacles are down line from the light switch. I have one fan plugged into one receptacle and about 12 feet after I have the other receptacle with the other fan plugged into it. The fans ran for about 8 minutes then threw the breaker. Then I looked at the tags on the fans. Here's what they say.

Horsepower 1
SF 1.25
PH 1
HZ 60
RPM 3450
Volts 208-230/115
Amp 6.6-6.0/12.0

My question is can I just change my switch and breaker to a 25 or 30 Amp or am I going to need to replace all the wire I just ran also? Many thanks for any help.

 

[WhoWhatNow]

Rewire it to a 220V 20amp curcit. The 12/2 should be fine for that. You will need two slots in your box.

 

[Charles (in GA)]

Two fans at 12 amps each for 115v equals 24 amps. No you cannot upsize the breaker alone. either replace the breaker with a double pole and make it 240v, but you need to change the switch to a double pole so as to interrupt both wires if you do that, and swap receptacles and plugs on the fans to the proper 240v receptacles to be safe. In addition, you would need to make the proper connections to the fan motor for 240v.

Other option is to run two separate circuits, thus two runs of wire, two switches, and two receptacles, or run a three wire circuit, known as a multiwire, with a shared neutral, in which case, you still need to have a double pole switch interrupting both hots and you still need a double pole circuit breaker.

Charles

 

[raddksn]

open the wiring compartment on each fan should be wiring diagram to change fans to 220v. then replace 1pole 20a breaker with 2pole 20a wire black 1side of breaker white to other side eliminate switch turn on and off with breaker

 

[HarleyJames]

Well, it cost me $200 and another days work but I think I got it fixed like I want it. I went back to the hardware store, bought a 30 Amp breaker, a 30 Amp double pole switch and 65 feet of 8/2 AWG Romex and re installed everything. I ran the fans for 25 minutes and no problems. I guess I'll use all the 12/2 Romex for some additional lighting.

 

[Aceman]

So you wired it up 240 volt?

Why did you buy #8 wire if that was the case? The circuit would only draw 6 amps per motor, 12 amps total. #12 would of been fine....??

 

[HarleyJames]

Its still 120v. I used the heavier wire so I could also hopefully run my water cooler when I get one or anything else I may want to run.

 

[brewchief]

Are the fans out of something else or are they purpose built for your use? If they are out of an old furnace check the amp draw, with nothing to restrict the air they will draw well over the nameplate amps. You can simply block off the inlet on one side until the amp draw is within spec.

 

[dave67fd]

Are the fans out of something else or are they purpose built for your use? If they are out of an old furnace check the amp draw, with nothing to restrict the air they will draw well over the nameplate amps. You can simply block off the inlet on one side until the amp draw is within spec.

You maybe correct on the thought that restriction of the airflow will slow the motor down decreasing current draw but torque will increase. Regardless, the listed FLA of the motor shouldn't be exceeded during full RPM, no load.