The circuit won't care. There is no benefit. On a dead short, any breaker will trip in less than 1 AC cycle.I'm not on site.
I wasn't asking for you guys to figure out what breakers to use. The manual says 20a and the HVAC company says 20a, so I will replace the 25 or 30a ones in there with 20s. I'm pretty sure they're 25s. What I was asking was what would the theoretical benefit be to using 20s on a circuit made for 25s. Is it just following the manual? Do the 20s trip easier? What sort of situation would happen where the 25s would not trip and the 20s would, and would it matter?
With automotive fuses, the smaller fuse burns out quicker, more likely saving the wiring in the case of a short. Is it the same for breakers? Or does a short trip the 20 and 25a breakers equally fast?
NO, nope, no, the fuse or circuit breaker cannot exceed the nameplate.here they require fuses within reach of the outdoor unit, and the fuses are determined by the name plate. The breaker can be equal or greater but the fuses have to match the nameplate. I would suggest posting the nameplate if you need a finite answer. Also there is normally a length part of the equation too. An outdoor unit 65' away may need a different gauge than one 20' away. Remember that it just isn't linear distance, there is wall climb into an attic and drop. That is all part of the overall length.
NO, nope, no, the fuse or circuit breaker cannot exceed the nameplate.
and how do you know it was because of an overload?I have trip a few AC motor breaker from overloads !
its called startup in-rush current. yes a 20 could trip where a 25 would notWhat I was asking was what would the theoretical benefit be to using 20s on a circuit made for 25s. Is it just following the manual? Do the 20s trip easier? What sort of situation would happen where the 25s would not trip and the 20s would, and would it matter?
here they require fuses within reach of the outdoor unit, and the fuses are determined by the name plate.
The breaker can be equal or greater but the fuses have to match the nameplate. I would suggest posting the nameplate if you need a finite answer. Also there is normally a length part of the equation too. An outdoor unit 65' away may need a different gauge than one 20' away. Remember that it just isn't linear distance, there is wall climb into an attic and drop. That is all part of the overall length.
As already asked: where is here? B/c this is BS. All you need is a disconnect at the unit. No OCP required at this location. Can you, yes, must you, no. Fuses at the disconnect location make sense only as a convenient place to accomplish required (when nameplate requires) fuse protection and service disconnect simultaneously.here they require fuses within reach of the outdoor unit, and the fuses are determined by the name plate. The breaker can be equal or greater but the fuses have to match the nameplate. I would suggest posting the nameplate if you need a finite answer. Also there is normally a length part of the equation too. An outdoor unit 65' away may need a different gauge than one 20' away. Remember that it just isn't linear distance, there is wall climb into an attic and drop. That is all part of the overall length.
I follow the thinking if #10 copper was used with a 30A cb (e.g.) and then the ckt "tuned" at the local disconnect with a permitted fuse/cb size <=MOC,It's perfectly acceptable to have a >20A breaker feeding a disconnect with 20A fuses or breakers in it. The breaker in the panel is there to protect the wiring, the breaker or fuse in the disconnect is for the equipment. It's very common to find this where the equipment was replaced and the new equipment is smaller or more efficient than the old. It's also common when a rough in for an AC is done during construction, and the equipment to be installed isn't known to the electrician. They can provide a 30A circuit, and the HVAC installer can fit appropriate protection in the disconnect. I'd bet at least half the houses that had AC installed before the 90s and have had the system replaced are like this.