Running DC fan From AC conversion is tripping breaker

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Old 04-06-18, 12:32 PM
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Running DC fan From AC conversion is tripping breaker

I have a custom built patio table with an automotive fan installed to blow cooled air. The fan is connected to a dimmer switch and a 10A fuse which is then connected to a converter (the ones that look like a laptop charger) which supplies 12V and 10A.

When plugged in and the dimmer switch off, there is no issue. Once the switch the is engaged, the GFCI thatís connect to that outlet is tripped. I do not have an outlet in my house thatís isnt connected to a GFCI somehow. The fan has functioned off a GFCI free outlet before.

Any advice? I can provide more details if needed.

Dan
 
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Old 04-06-18, 01:32 PM
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What type of dimmer are you using.
You would need a dimmer specifically for a DC input and the specific voltage you are working with.
For automotive use they are normally a rheostat or resistors.
 
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Old 04-07-18, 11:53 AM
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Here is the wiring and the back of the converter. The Dimmer doesnít have any identifying info on it; no text or any markings.
 

Last edited by GingerDan; 04-07-18 at 11:53 AM. Reason: Autocorrect
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Old 04-07-18, 09:45 PM
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That's a PWM (pulse width modulated) dimmer for 12vdc.
That's in a plastic case so I doubt it's the problem.

That power supply probably has the 12v negative wire tied to ground internally. My guess is the fan motor has a leak to ground causing the trip. If you have an ohmmeter...... disconnect the fan from the circuit and check from each wire to ground. There should be no continuity measured.
 
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Old 04-09-18, 12:53 PM
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We tried the fan on a non-GFI outlet and tripped the circuit breaker. We eliminated the dimmer variable and connected the fan directly to the converter but still tripped the circuit breaker. We have one non-gfi and non-arc fault outlet in our house. We used that outlet and the fan functioned normally. Our circuit breakers are 20A.

Other than running a new breaker just for the fan, are you aware of any different converters or other options? Maybe thereís a more heavy duty converter with a capacitor to handle the initial draw?

Thank you for your help.
 
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Old 04-09-18, 01:35 PM
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We tried the fan on a non-GFI outlet and tripped the circuit breaker.
You tripped a GFI or arc fault breaker. Not a standard breaker.

A GFI trips when it measures an imbalance between the hot and the neutral. That means it's looking for leakage to ground. If you plug in just the power supply and nothing trips.... the power supply is ok. If you plug it in with the fan connected and it trips.... the fan is shorted to ground. Not that it would cause a short but it has continuity to ground. Maybe the windings got wet or are old.

The one way to run that is to use a 120vac to 12vdc transformer type power supply. This will be tough as all power supplies claim to be transformer type.... and they are... but they are switching power supplies. A true transformer type power supply is isolated from ground by the transformer. This in not the least expensive way to remedy the situation.

Pyramid-12-Amp-Power-Supply

A meter would really be helpful to find the actual problem.
 
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