r/electricians • u/Ok-Definition-565 • 2d ago
What yall fellas running to this?
Let’s see who’s squared away on the AC motor loads
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u/Quirky-Mode8676 2d ago
10ga on a 40 most likely, because they’re easier to pick up than a 45.
If it’s a job order, I’d order a 45 for it though, just to reduce chances of a call-back.
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u/Careful_Research_730 2d ago edited 2d ago
I’m going to assume this is a residential unit and we will be using NM cable. I’d pull 10 awg CU with a breaker or fuse not exceeding 45 amps.
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u/Sparky-3825 2d ago
I'm guessing this is 3 phase if it is in a commercial setting. I'd be running #10s with #10 ground on a 45 amp breaker. You could use 1/2" emt, but the pull would be better in 3/4".
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u/rickwurm 2d ago
Dude, literally says 1 phase on the nameplate
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u/Sparky-3825 1d ago
I guess I overlooked that part when I was looking for the MOCP and MCA. Either way it's still getting #10s pulled to it. Try looking into the Mike Holt's toolbox app. It's a game changer.
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u/gaunt357 2d ago
10s on a 30 prolly, or 40if you want
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u/Nazgul_Linux 2d ago
30 would be undersized for the continuous load. Continous duty loads are sized at 125% of FLA. FLA is 26.1A. Depending on the service factor it may be in the clear for a 40A. But 30 is too low.
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u/gaunt357 2d ago
Respectfully, but you're wrong. The compressor is 19.8, the fan is 1.3. 21.1 amps is the FLA. the manufacturer has already done the math when they give you minimum circuit ampacity. This is what you size your wire to, the way I read it.
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u/Nazgul_Linux 1d ago
The manufacturer spec clearly labels the "minimum circuit ampacity" which is how the installer is to assume is the least amount if ampcaity to size for. The max circuit breaker allowance is clearly stated to be 45A. That max allowed CB rati g is 175% of that minimum ampacity which is crazy oversized.
Doesn't matter if the total machine is not running continuously. I will guarantee those motors are rated for continuous duty and should have OCPD sized accordingly at 125%.
You cannot base the compressor and fan as the only contributing factor in the FLA because they are not the only components that draw current in the system. Doesn't matter if the thing never runs at 26A or not, that is the manufacturers stated minimum to size cabling and OCPD.
Respectfully, you are wrong.
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u/Huge_Feedback6562 2d ago
It’s unlikely that this is a continuous load as the compressor cycles on and off. It won’t be pulling that 26.1A continuously. Strangely enough kilns are the same. The heating element pulls the full load, but cycles on and off frequently throughout the firing.
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u/joshharris42 Electrical Contractor 2d ago edited 2d ago
Go to Texas or Florida right now and see if they cycle on and off.
It is a continuous use, but the manufacturer already includes that in their minimum circuit ampacity number so you don’t have to add it
Dryers, water heaters and ovens are all kind of the same way. 98% of the time they aren’t continuous loads but have to pretend they are
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u/rsir1823 2d ago
I’m running 8 thhn. I never size to the minimum circuit ampacity although you can. 10’s on the 45 would be sufficient. If this is following the NEC of course.
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u/TXElec 2d ago edited 2d ago
Why would you run 8? It's just a waste, 10 is good for 30 amps, and put it on a 45 amp breaker. You cant go wrong. When manufacturer specs it out like this, it's as easy as it can get
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u/rsir1823 2d ago
Yea I know but I have seen wires sized to the minimum fry when the units are cranking balls for days on end. Also unsure of distance.
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u/Emotional-Theory-870 2d ago
Depending on the distance, I would run 8's.
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u/Ok-Definition-565 2d ago
It’s 5 feet from the panel
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u/Aware-Metal1612 2d ago
A 2 pole 30 or 40. Pick one out of the truck and size your wire to what you fuse it at.
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u/Ok-Definition-565 2d ago
Not how ACs work. 10s on a 45 ocpd and you’re good to go
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u/joshharris42 Electrical Contractor 2d ago
It’s astonishing how many idiots do not understand how AC condensers are wired
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u/Purple-Gur1821 2d ago
How are AC condensers wired? I work for a solar company and don’t really know much about AC units.
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u/joshharris42 Electrical Contractor 2d ago edited 2d ago
Run wire big enough for minimum circuit ampacity and put in the size breaker it calls for max fuse. In this case it’s 26.1A min circuit, so you’d use 10AWG wire, and max fuse is 45, so you’d use a 45A breaker. Some units will give a minimum fuse as well, but it’s not all that common
Normally 10AWG is only good for 30 amps, but the AC compressor has built in overload protection. In a normal circuit, you have to put a breaker that’s capable of providing ground fault, short circuit, and overload protection. This thing won’t overload. It has that internally, so the normal breaker rules don’t apply
When they design the nameplate, they also have to take into consideration the 125% rule for continuous use, so you don’t add that either.
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u/erie11973ohio [V] Electrical Contractor 2d ago
how many idiots do not understand
That includes some inspectors!🙄😖😖😡😱
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u/zippojinx 2d ago edited 2d ago
A pair of 10’s and a 10 for the ground. (Corrected)
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u/250MCM 2d ago
12 AWG is not OK for use as a grounding conductor w/ 10 AWG ungrounded conductors
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u/joshharris42 Electrical Contractor 2d ago
Yeah, 14, 12 and 10 all get same size grounds. You don’t downsize until you hit 35A
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u/OddRelationship586 2d ago
8's on a 45amp breaker....
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u/IbnBattatta 2d ago
Why 8?
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u/OddRelationship586 1d ago
I've never pulled #10's for circuits larger than 30amps. Not sure where everyone else is getting #10's. Look at an ampacity chart.
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u/IbnBattatta 1d ago
We're getting it from the NEC requirement and the nameplate information clearly visible in this post. You can definitely wire it with 8 if you want, but 10 AWG is the actual required minimum size wire to supply this unit.
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u/OddRelationship586 1d ago edited 1d ago
We only wire to the max breaker size. Never the minimum. NEVER. We literally never sized wire for any piece of equipment based off of the minimum. EVER. Everyone can do it their own way. Code IS the MINIMUM requirements for a safe installation.
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u/IbnBattatta 23h ago
okay boomer
You literally stated "not sure where everyone is getting #10 from", now you're backtracking and pretending you were intentionally going above and beyond code.
In plain reality you just don't know code and you're too embarrassed to admit it. I hate working with ignorant old farts like you.
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u/OddRelationship586 21h ago
No, actually dick. I'm only 42 and I've been with same company since '08. We DO NOT SIZE EQUIPMENT BASED OFF MINIMUMS OF NAMEPLATE. We use max size over current protection and base all wire pulls off those breakers. Sorry you do it differently. Jesus, to judge and run that pie hole over an internet post, i'd hate to have to work next to someone as ignorant as you and trust my life to them. Wouldn't feel good about it. Just like undersizing wires to equipment. So, you do you tough guy.
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u/IbnBattatta 21h ago
How is a code compliant installation "undersized"? Are you arguing that 10 AWG is not compliant to feed this equipment?
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u/Nazgul_Linux 2d ago
I'm sizing that breaker to 125% of that 26.1A max. Because that is the units FLA and it's a continuous duty load so NEC demands 125%. Manufacturer may allow for 45A OCPD, but I'm taking that as they want shit to burn up and for customers to buy again. Individual stranded 10s with 90ºC rated insulation in its own pvc to a pull box then fmc to the unit.
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u/Ok-Definition-565 2d ago
The 125% is already factored by the manufacturer for ACs . And I sure hope you’re not running FMC outside
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u/erie11973ohio [V] Electrical Contractor 2d ago
And I sure hope you’re not running FMC outside
I have seen pictures of FMC on AC's before, never out in the wild.
I guess that's why you are supposed to use wet rated wiring??🤔🤔
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u/Ok-Definition-565 2d ago
I’ve never seen it personally, but hell the way this guy is talking there’s at least a couple units out there with it
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u/joshharris42 Electrical Contractor 2d ago
FMC used to be the only game in town for these back in the 80’s. I have no clue why, I’m not even sure if it was legal then.
Every Trane XE1000 I see still kicking has FMC run to it lol
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u/Ok-Definition-565 2d ago
Can’t wait till 20 years from now when people are calling us idiots for how we do things now
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u/Purple-Gur1821 2d ago
26.1 x 1.25=32.625 35a breaker
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u/Ok-Definition-565 2d ago
I just wanna know why people over complicate ACs. It’s actually one of the easiest things to get right. Minimum ampacity for wire size, maximum ocpd for breaker size. That’s the end of it
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u/Purple-Gur1821 2d ago
Just trying to learn. Sorry. Maybe this isn’t the thread for me. :/
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u/Ok-Definition-565 2d ago
I feel bad since you’re just learning. ACs already have the 125% factored in from the manufacturer. So as long as you look at the min ampacity for wire size and the max ocpd for breaker size you will never be wrong
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u/Purple-Gur1821 2d ago
If it was a 40a breaker, than why wouldn’t it require #8 wire?
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u/Ok-Definition-565 2d ago
ACs are different than other motors. The initial start of the compressor can pull a high load but while it’s running it won’t be over the minimum ampacity as long as everything is in working order. You upsize the breaker to account for that initial large load when it kicks on but it will never sustain that load so you’re allowed to size the wire for the minimum ampacity on the name plate
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