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kalvin · Jul 16, 2008, 01:52 PM

Hello all:
Looking to run power to back garage about 170' from panel box. There will be no big loads in the garage (small compressor, lights, garage door, couple of battery tenders.

Questions is can I run #4 wire off a 60 amp breaker into a panel in the garage. I will not have a main breaker in the garage but will have a few 20 amp breakers in there to power plugs and lights etc.

Any help would be great.

Thanks.

donf · Jul 16, 2008, 06:05 PM

Back up, you need to do a rough determination of the load you need. 20 amp 30 amp you need to know that before connecting wires up. What is the total amperage being fed to the sup panel that is already in the garage?

Can you help us please?

kalvin · Jul 17, 2008, 04:21 AM

Garage is new.. 30 amps would be on the high side as this is a garage to park cars not a shop..
Plan now is 60 amp dopuble pull breaker in the home panel running to a disconnect on the outside of the house then #4 wire urd to the garage panel with 2-3 20 amp breakers in it.. of course gfi for all plugs in the garage, and no gfi for the door opener.

donf · Jul 17, 2008, 07:27 AM

Kal,

If you are planning on a 170' run of 120/ 30 Amp from a panel in the same room, you will only need #10 AWG. Of course that's if the calculator I used is correct.

If you already have a panel in the garage, why do you want an outside cut off. If there is an emergency, you want an emergency cut off as close to you as possible?

kalvin · Jul 17, 2008, 02:07 PM

Don,
Sorry I do not explain things very well.. The 170' is from the main panel box in the house running out to a sub panel in the detached garage which is new and has NO electric yet. Like I said the load is minimal as I have a shop elsewhere so this is for car parking and battery tenders, small 120v compressor etc..

I am questioning the size of the wire from the house to the garage subpanel

Washington1 · Jul 19, 2008, 05:00 PM

#4 Alum will work, and is suggested for no more than a 170 ft run @ 30-40 amps.

Washington1 · Jul 19, 2008, 05:06 PM

Please note that I'm considering volatge drop (Which is not required by NEC)

donf · Jul 30, 2008, 01:47 PM

Kalvin,

Perhaps you did not read my response correctly. You referenced a 60 amp breaker but you gave no indication of what the expected load would be.

Also, You have to consider the voltage drop. On a 120 VAC line, the drop cannot be more than 3.2%. On a 240 VAC line, it cannot be more than 7.2%.

All I did was ask you to tell us what the anticipated load would be. How does that merit a disagreement? Is it against some rule of yours to answer questions?

tkrussell · Jul 30, 2008, 01:57 PM

Don, this post has the answer to your question:

Originally Posted by kalvin

Garage is new .. 30 amps would be on the high side as this is a garage to park cars not a shop ..
plan now is 60 amp dopuble pull breaker in the home panel running to a disconnect on the outside of the house then #4 wire urd to the garage panel with 2-3 20 amp breakers in it .. of course gfi for all plugs in the garage, and no gfi for the door opener.

Use 30 amps to size the conductor for voltage drop at the 170 feet, and be done with it.

tkrussell · Jul 30, 2008, 02:00 PM

Don, this post has the answer to your question:

Originally Posted by kalvin

Garage is new .. 30 amps would be on the high side as this is a garage to park cars not a shop ..
plan now is 60 amp dopuble pull breaker in the home panel running to a disconnect on the outside of the house then #4 wire urd to the garage panel with 2-3 20 amp breakers in it .. of course gfi for all plugs in the garage, and no gfi for the door opener.

Use 30 amps to size the conductor for voltage drop at the 170 feet, and be done with it.

Also you mis-spoke:

Originally Posted by donf

he drop cannot be more than 3.2%. On a 240 VAC line, it cannot be more than 7.2%.

You meant to say 3.6 VOLTS for 120 and 7.2 VOLTS for 240 volts.

And, these are NOT mandatory, only recommended by NEC and IEEE.

donf · Jul 30, 2008, 02:01 PM

Kevin,

That response from Kalvin was not in the item when I posted my response/question. Basically, Kalvin disagreed with my asking a question of him and then he entered the answer to my question. Go figure, no harm done unless you have a phobia about disagrees. Kev, here's the happy face again :) Don

tkrussell · Jul 30, 2008, 02:05 PM

I don't give a rats azz about disagreement comments.

Or pay any attention to the little faces.

You asked in post #2, the answer was in post #3.

Also, did you see my comment about the Vd % and volts?

Washington1 · Jul 30, 2008, 02:19 PM

Originally Posted by tkrussell

Don, this post has the answer to your question:

Use 30 amps to size the conductor for voltage drop at the 170 feet, and be done with it.

Also you mis-spoke:

You meant to say 3.6 VOLTS for 120 and 7.2 VOLTS for 240 volts.

And, these are NOT mandatory, only recommended by NEC and IEEE.

I agree 100%!

donf · Jul 31, 2008, 07:26 AM

Kev,

Yes, I saw your comments on the Voltage Drop.