Watching the advanced electrical training videos, I have a question regarding the AWGs and breakers. In the video, there was a 10 AWG put into a 60 amp breaker. In both electrical courses, the highest amp is 30. Can someone explain this like I am a two year old please?
Motor loads are different, check the data plate.
In this example picture below the “minimum circuit ampacity” (the ampacity level used for sizing the wires for that equipment.)is 28.8 amps, which needs a 10 gauge wire and the “maximum fuse or circuit brkr” (Largest over current protection device allowed for that equipment) is 50 amp.
If within the data plate parameters, you are good.
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What type of load was it feeding?
The video said it was HVAC system.
Looking at the example you provided, then the 60 was still incorrect with the 10 AWG.
The video said it was HVAC system.
Looking at the example you provided, then the 60 was still incorrect with the 10 AWG.
Damon, if you are referring to my example picture, it is a manufacturer’s data plate picture so the manufacturer says it is fine with 10 awg wire on a 50 amp breaker.
If, in your video example where the 10 awg wire is on a 60 amp breaker, the manufacturer’s data plate that an inspector would look at on the HVAC equipment says it is fine then it is fine.
The inspector has to verify the wire size attached to the breaker with the allowable wire size on the data plate on the HVAC equipment.
It is the inspector’s responsibility to do that.
Do you understand now?
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Larry’s example was just that an example. It likely does not represent the information giving in the training that you’re asking about.
An AC unit nameplate will typically have a great deal of information (see Larry’s photo) but the relevant information for a home inspector is the Minimum Circuit Ampacity (MCA) and the Maximum fuse or circuit breaker sometimes abbreviated MaxOCPD.
In Larry’s example the MCA is 28.8 amps, the MaxOCPD is 50 amps. You would use the MCA to size the conductors, #10 NM cable is rated for 30 amps so that is good. The MaxOCPD is the size of the circuit breaker or fuse protecting the branch circuit so that could be 50 amps.
Key takeaway is that for AC units the conductor size does not have to match or be larger than the OCPD protecting the circuit.
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Where did the #8 come from? The OP mentioned #10 AWG.
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These numbers you’re using are not relevant to the OP’s questions. Where did you get 34 amps from? Also a #10 AWG conductor is actually rated for 35 amps at 75° C as long as you’re not using NM cable.
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If anything, it seems to be sowing more confusion for the OP’s uncertainty.
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It’s great when everyone participates but as you’ve said inaccurate answers will only confuse the person asking the question. Some of the responses in this thread seem to be copy and paste of AI searches.
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Sorry, you are correct I was looking at something else. But the math and the code does not change. 10 gage wire at 30 amps as long as it is greater then minimum circuit ampacity on the units. For an AC unit you can oversize the breaker by 175% of 30 amps is 52.5 amps and you are allowed to round up to the next standard size breaker. Either 55 or 60 depending on manufacturer.as long as you don’t exceed 225% of the rating. But in the example because the name plate says 50 that becomes the maximum size breaker as manufacturer specifications override code in this case. That said the voltage drop when the ac unit kicks on will be very noticeable and I would never use such small wires, especially if the AC unit is far away from the panel. So specifically to his question you are allowed to protect the 10 awg with a 60 amp breaker under electrical code for an AC, As long as it does not exceed the manufacturers specifications. Also I am a Licensed Electrician in OHIO and 2023 code is enforced, but this provision has not changed for many years.
The MCA already has 125% added to the largest load which is the compressor. Any calculations would use the actual nameplate current not the MCA. But all of this is moot because the manufacturer is required to provide both the MCA .and the MaxOCPD on the nameplate. A home inspector should only be concerned with those numbers.
True. And in my experience, it is very rarely an issue. More often than not from what I have witnessed here, it is inspector error.
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Jeff also being an electrician understands the NEC calculation behind the numbers. For the HI’s the simple nameplate numbers are good enough.
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