A/C circuit wire too small

Status
Not open for further replies.
Mr. Serious

Mr. Serious

Senior Member
Location
Oklahoma, USA
Occupation
Electrical Contractor
Last year, on my first rough-in job after becoming a contractor, I wasn't given the specifications for the air conditioners, so I guessed, and I ran #12 on a 20-amp circuit to one of them. Now the actual air conditioner is here. It says the input current is 20.0 amps, but the minimum circuit ampacity is 30 amps.

I have to change the wire to #10 and the breaker to at least a 30-amp, don't I?

AC.jpg
 
Mr. Serious said:
Last year, on my first rough-in job after becoming a contractor, I wasn't given the specifications for the air conditioners, so I guessed, and I ran #12 on a 20-amp circuit to one of them. Now the actual air conditioner is here. It says the input current is 20.0 amps, but the minimum circuit ampacity is 30 amps.

I have to change the wire to #10 and the breaker to at least a 30-amp, don't I?

View attachment 2560935
Click to expand...
Unfortunately yes you do. I don’t know anyways around it.
 
OK, thank you. I had never seen a label exactly like this, and I was thinking, maybe the wire can be sized for the 20 amps. But realistically, I still have to size for what it says for minimum circuit ampacity.

Right after I finished the rough-in, I drove past a new house done by another contractor and noticed the #10 stub-out for the air conditioner, and I thought "I'll have to do that next time, just in case."
 
I agree you need at least #10 conductors. What's with the requirement for fuses on the nameplate? Is that just poor Chinese language translation.
 
infinity said:
I agree you need at least #10 conductors. What's with the requirement for fuses on the nameplate? Is that just poor Chinese language translation.
Click to expand...
Mr Cool - The DIY minisplit systems, made in China. looks like this one can support 1 to four indoor units.

The fuses? Did I say made in China?
 
If it is variable speed compressor I find it hard to believe it ever needs more than a 30 amp fuse. 45 amp is about what size breaker would typically be needed for across the line starting though. Me thinks they don't really know how to mark them.
 
I haven't paid attention much to whether they say fuse or breaker. I thought they just always said MAX FUSE, but maybe that was decades ago.
 
kwired said:
You would have paid attention if you had inspectors rejecting them if they only mentioned fuses and you didn't use fuses. ;)
Click to expand...
Good point. I think that foreign manufacturers just use the term fuse when they actually mean OCPD. We did an apartment complex that had at least 2000 of these units from Canada that were labeled Max fuse size. Just out of curiosity I emailed the company asking for a clarification but they never responded. No one ever mentioned this on the job either so it was just left with a circuit breaker.

20180301_100603.jpg
 
infinity said:
Good point. I think that foreign manufacturers just use the term fuse when they actually mean OCPD. We did an apartment complex that had at least 2000 of these units from Canada that were labeled Max fuse size. Just out of curiosity I emailed the company asking for a clarification but they never responded. No one ever mentioned this on the job either so it was just left with a circuit breaker.

View attachment 2560937
Click to expand...
I've noticed that too. If foreign manufacturer, even Canada, it often just marked fuses in some way or another. US made or even foreign made or partially foreign made with a US company label will nearly always say fuse or breaker in some manner.
 
infinity said:
I didn't see the HACR breaker mentioned.
Click to expand...
No, it isn't mentioned. I was trying to say that many units- residential ones- usually state max fuse or Hacr breaker. I haven't seen a residential unit that stated max fuse in 30 years.

By the way, didn't it use to say Max Fuse Only
 
kwired said:
I've noticed that too. If foreign manufacturer it often just marked fuses in some way or another. US made or even foreign made or partially foreign made with a US company label will nearly always say fuse or breaker in some manner.
Click to expand...


I thought that most of the 3 phase units stated Fuse Only... Has that changed?
 
Dennis Alwon said:
No, it isn't mentioned. I was trying to say that many units- residential ones- usually state max fuse or Hacr breaker. I haven't seen a residential unit that stated max fuse in 30 years.

By the way, didn't it use to say Max Fuse Only
Click to expand...
I think so that's why I'm thinking that these foreign manufacturers are using the word fuse to mean OCPD.
 
Status
Not open for further replies.
Top