Two different wire sizes for 30 amp breakers?

I have a panel with different sized wires for 30 amp breakers. Is this allowed?

What size were they …They all look like #12 which would be wrong for 30…
What were they feeding?

Looks like a #12 and a #10 and a lot of spray paint white. LOL

You think the 30 amp is #10?
That would be ok.

Looks like one of each Roy on that double pole 30 amp breaker. But I’m 1,000 miles away. LOL

Impossible to tell for certain from a picture but the right side appears to be 8 awg aluminum (good) & the left appears 10 awg copper (also good)
In summary, I see nothing wrong with the two 30amp breakers pictured.

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We have to know what size and type wire to answer you. The wiring can be oversized. The wiring may be larger on one if it’s stranded aluminum as 8 awg would be correct size.

Great info! I’ll check. Thanks!

With some types of Heating Ventilating and Air Conditioning, Motor, and Refrigeration loads the conductors supplied by a 30 ampere overcurrent protective device can be smaller than number 10 American Wire Gauge (AWG). For instance the name plate of an Air Conditioner Compressor may have 12 as the minimum size of the supply conductors and 30 Amperes as the maximum size of the circuit protective device. The reason that the manufacturer may specify the supply circuit that way is that the overload protection for both the supply conductors and the Motor-Compressor itself are located in the outdoor Compressor housing so the 30 ampere instantaneous trip breaker is only providing ground fault and short circuit protection to the circuit conductors.

When you already have black, red, and green #12AWG on the truck and you used up your last bit of #10AWG you look for that on the manufacturers name plate before you make an unnecessary trip to the supply house. To those that say one should not have run out of the #10 I will conclude that you have never had the dispatcher or the supervisor page or telephone you on the road and say “Before you go there I need you to knock out this recall, punch out item, or service call…”


Tom Horne

Across a jobsite basement wall in marker paint letters that were 4 foot high “I want the pager number of the fella who invented the pager!”

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:sweat_smile:
My company gave me a pager you could not turn vibrate off.
I was on top of a 5 story building with my hands in a 480vac 3 phase HVAC service panel and my ass started vibrating! When I got back to the shop they asked me why I didn’t answer my pager?

:rage: “I threw it off the building into the parking lot”. I never carried a pager outside my truck again!

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Mine did the same to me when I was atop a 20 foot A frame ladder. Thank God I had tethered my harness to the bar joist. I couldn’t afford to through mine away though. I was a call out fire alarm technician so that payed over scale and I got paid for standby time The position was pretty well paid. I still hated that thing and when they ended the standby time pay I turned it in until they repented that decision. I was the guy that always answered the page so they had to reinstate the standby time pay. I was dammed determined not to carry one for free.


Tom Horne

Thanks, the two are for the AC unit. They are not tied together, however,

From your pictures I see only two 240v, 30 amp circuits. (1 on left, other on right) Each of those circuits are tied properly.

While others are correct about using smaller awg conductors with the 30 amp breaker when equipment ampacity allows, that does not appear to be the situation you are in…according to the 2 pictures & description in the OP.

So, in an effort to clarify.
Are you asking why the conductors used on the left side 30amp circuit is a different physical size than the conductors used on the right side 30amp circuit?