Repurposing AC feeder for garage/shop 220 tools?

[Revtor]

Hey guys new member here with a question about garage wiring, trying to fit in outlets for a new welder and 220v single phase belt sander.

My initial thoughts after a bit of research was run 6/3+g romex from the main panel, to a small box in the garage (the garage is attached) and use two 30amp breakers in the box, one for each receptacle. Put a 60 amp breaker in the main panel for this garage feed.

That seemed all well and good but it turns out that there are no more slots on the main panel (200 amp service)!!! So i have to get crafty perhaps. What is already running to the garage is two cables for the AC units which are situated right outside the garage wall. One is fed from a 60 breaker at the main panel and the other a 70 amp breaker. These run to disconnect boxes outside the wall right near the units. (Ive used a homemade jumper cable extension to run right from the disconnect boxes but I really really don't like doing that and want to set this up the right way, thus this long message!)

So, I was thinking, could I use the 70 cable to feed a subpanel and then in that panel branch off for the two AC units? Thus freeing up the 60 amp for my shop tools.
The two AC units are rated as follows:
One says "Min Circuit ampacity 37.6 amps, and Max Circuit breaker 55 amps" the other "Min circuit ampacity 28.9 amps, andMax circuit breaker 45 amps"

I'll end this here.
Any thoughts guys?

thanks a lot!!

~Steve in NJ

 

[Aceman]

One is fed from a 60 breaker at the main panel and the other a 70 amp breaker. These run to disconnect boxes outside the wall right near the units. (Ive used a homemade jumper cable extension to run right from the disconnect boxes but I really really don't like doing that and want to set this up the right way, thus this long message!)

So, I was thinking, could I use the 70 cable to feed a subpanel and then in that panel branch off for the two AC units? Thus freeing up the 60 amp for my shop tools.
The two AC units are rated as follows:
One says "Min Circuit ampacity 37.6 amps, and Max Circuit breaker 55 amps" the other "Min circuit ampacity 28.9 amps, andMax circuit breaker 45 amps"
~Steve in NJ

I would not try to repurpose the AC unit feeds for a 240v ONLY subpanel.

You have me curious though, you stated you have a 70 and 60 amp breaker feeding AC units requiring max breaker sizes of 55 and 45 respectively. Do your AC units have fused disconnects with the proper size fuses in them?

What size and kind of cable is attached to each of those AC unit breakers in your panel?

 

[Revtor]

Aceman, good questions, thanks for the reply. I looked, there is 6/3 feeding both, and at the fused disconnect boxes (outside, near the units) there are big *** 60 amp fuses in ea. So yeah, kinda iffy there.. The fuses should be 55 and 45 I guess?

~Steve

 

[Aceman]

Since those are max ratings, I would use 50 and 40 amp fuses instead, they will be easier to find.

 

[Charles (in GA)]

What is the model number of the panel? If it is something like 3040 then it has 30 spaces but can handle 40 circuts by using thin half width breakers in the bottom 5 slots on either side. It also may be possible to combine some circuits and free up a couple of spaces.

Charles

 

[alfredeneuman]

55 amp isn't a standard fuse size.
You're allowed by Code to use the next standard larger fuse (up to 800 amps) size,
which in this case, is 60 amps.

45 amp is a standard fuse size. By all means, get the 60s out of there and replace them with 45s.

 

[Revtor]

I'll install the correct fuses for sure..

Not sure of the model# of the panel, but there are a few half width double breakers in there already. Maybe I can condense a bit and open a few slots for another 220 garage feed. Looking at everything though, I don't know if there should be another 60 amp beaker in there! Whats the rule for combined rating of all the breakers vs the main feed breaker to the panel?

~Steve

 

[wyliesdiesels]

First off, what type of wire is the 6/3 NM- AL or CU?

There are many reasons why hooking up both AC condensors onto the same branch circuit wont work:

1) u run into NEC tap rules
2) u would most likely have to upsize the breaker to prevent nuissance tripping due to motor in-rush currents, however, we dont know this for sure since u didnt state the HP of the condensor fan and compressor in each unit
3) the UL listing on the units would be violated if they say "dedicated circuit" and also if u have to upsize the breaker due to what i said in #2. This has actually already happened since the wrong size fuses are being used
4) The wire is most likely the wrong size since wire for motor circuits is sized at 125% of FLC, which the manufacturer already gave u the info for.

IMHO, It will be easier to run a new cable to a new subpanel

I'll install the correct fuses for sure..

Not sure of the model# of the panel, but there are a few half width double breakers in there already. Maybe I can condense a bit and open a few slots for another 220 garage feed. Looking at everything though, I don't know if there should be another 60 amp beaker in there! Whats the rule for combined rating of all the breakers vs the main feed breaker to the panel?

~Steve

There is no rule. And BTW the nominal voltage is 240v, 220v hasnt been used in the US for decades.

 

[Revtor]

Allright Wylies, I'll drop the 2 into one idea..

Hopefully I can get a run off this main panel, there are a few unused things I think that oculd probably be dropped. Got to do some more poking around.

thanks again all

~Steve

 

[Mustang51js]

Get a couple tandom breakers to free up some space,or combine a couple things that don't need to be on it's own circuit