If I wanted to install an in line circuit breaker on the feed line for a fridge compressor as an extra safety, ho would I determine the correct size and type?
The compressor is rated at 221 watts and runs on 110 to 120 ac.
also would an auto resetting one be okay?

 

Also. It is rated for 15 locked rotor amps

 

Most sealed unit refrigeration compressors include an over-temperature cutout that resets after it cools off. For most applications that is entirely adequate.
I did see one instance with an older refrigerator in which the compressor would not start but keep trying until the over temperature switch opened, then it cooled for about minutes and tried again. That house had enough wire resistance that the current never cleared the mains fuse, and so the cycle repeated for over a week. When I discovered it the floor beneath the compressor was slightly charred, so it was on the way toward starting a fire. The compressor was touching the floor because the rubber isolation mounts had failed long ago..
That refrigerator was at least 5 years old.

Despite that one observed failure, an inline circuit breaker adds potential failure points in a circuit that is important to maintain, to preserve the contents.

 

Most sealed unit refrigeration compressors include an over-temperature cutout that resets after it cools off. For most applications that is entirely adequate.
I did see one instance with an older refrigerator in which the compressor would not start but keep trying until the over temperature switch opened, then it cooled for about minutes and tried again. That house had enough wire resistance that the current never cleared the mains fuse, and so the cycle repeated for over a week. When I discovered it the floor beneath the compressor was slightly charred, so it was on the way toward starting a fire. The compressor was touching the floor because the rubber isolation mounts had failed long ago..
That refrigerator was at least 5 years old.

Despite that one observed failure, an inline circuit breaker adds potential failure points in a circuit that is important to maintain, to preserve the contents.

ok. What about fail safes for the Ssr?
Here are actual compressor specs:

1/3- hp Displacement 7.7cc From 100W to 671W Cooling (341 to 2289BTUs) ASHRAE : 220w - 751btu 110-120VAC 50-60Hz R134A Low Back Pressure PTC Starting Relay Motor Type CSIR Includes electricals, grommets and sleeves. Cooling capacity ASHRAE -35C (-31F) - 100w - 341btu -30C(-22F) - 130w - 444btu -25C(-13F) - 169w - 577btu -23.3C(-10F) - 220w - 751btu - input power 165W - current 2.40 Amps - COP 1.35 - EER 4.55 -20C(-4F) - 275w - 938btu -15C(5F) - 344w - 1174btu -10C(10F) - 430w - 1467btu -5C(23F) - 537w - 1832btu 0C(32F) - 671w - 2289btu Certification : UL Underwriters Laboratories Recognized Nationally Recognized Testing Laboratories (NRTL)

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If you do add a breaker or fuse, you might want to add a warning circuit that indicates the loss of power when the breaker/fuse opens.

 

Extra Safety against what ?
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Extra Safety against what ?
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Ssr failing closed,damage to the input circuit, etc

 

The wayto warn of control failures is with a temperature sensing switch. over or under the set temperature range an alarm lights up and the failure is announced.

 

The 120 volt circuit going to the condenser fan is .08 mA. I am having trouble finding a Ssr that will turn on with that low of a current. Does one exist?

 

The 120 volt circuit going to the condenser fan is .08 mA. I am having trouble finding a Ssr that will turn on with that low of a current. Does one exist?

That current, 0.08mA, is neither reasonable nor believable. So I suggest that the number is either a misprint or a mis-reading. Where did that number come from??
There has been no mention of a condenser fan in this thread until now.
Could this answer be intended for the thread where a BLDC compressor is being replaced??? I had just suggested using an SSR to sense that the condenser fan was powered in that thread.

 

That current, 0.08mA, is neither reasonable nor believable. So I suggest that the number is either a misprint or a mis-reading. Where did that number come from??
There has been no mention of a condenser fan in this thread until now.
Could this answer be intended for the thread where a BLDC compressor is being replaced??? I had just suggested using an SSR to sense that the condenser fan was powered in that thread.

Sorry, yes I guess I put in wrong thread

 

I've scrapped a number of old treadmills. Every one of them have had a 15 amp circuit breaker built into the unit. For sure it is an "in-line" breaker. IF your main circuit is 15 amps and you have an extra 15 amp breaker in line there would be no problem. But if you have the same 15 amp circuit and you put a 20 amp in line breaker you're not going to ever see it do a satisfactory job. Conversely you can have a 20 or 30 amp circuit and a 15 amp in line breaker with no problems or issues. If your equipment fails then the 15A breaker will break the circuit. As long as you never go for a higher rating than what the wiring is designed to operate safely at then there should be no problem.

NEVER EVER replace a 15 amp breaker with a 20 or 30 amp breaker. The wiring is likely 14 gauge and rated for 15 amp service. However, you're ok if you replace a 20 amp breaker with a 15 amp breaker as long as the original circuit was designed to operate on 20 amps. Heck - you could go with a 2 amp breaker if you desired in that last case. And I say that merely as an EXTREME example. You're not going to find a 2 amp breaker very easily. Certainly not one designed for a home circuit breaker panel.

 

The exceptions being the time lag factor of different breakers. Especially in larger power distribution systems, it is appropriate to have the farther out breakers set to trip more rapidly than those protecting a larger area. When the main breakers were very fast to trip we routinely had large area blackouts. But after the delay settings were adjusted, the blackouts were limited to the vicinity of the triggering fault. This was a great improvement. I was amazed that the utility engineer in charge had not been aware of adjustable trip delays. (I was the one who suggested investigating and adjusting. them)