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Electric Question, possibility of splitting a 60amp circuit?

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Forum topic by onesojourner posted 09-17-2013 10:41 PM 1645 views 0 times favorited 17 replies Add to Favorites Watch
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onesojourner

41 posts in 469 days


09-17-2013 10:41 PM

I just finished building my house. I did all the wiring with the oversight of a licensed electrician. My original plan was to build a separate shop, but that has been pushed back by several years. So part of the unfinished basement is going to be the wood shop for the foreseeable future.

I have 4 stubbed out 20 amp circuits down there. There is no even remotely easy way to pull more wire down there.

I do have an all electric furnace heat pump with 60amp back up heat strips. Our primary heat source is going to be a wood stove. I won’t say that we will never get into the strips but it should be a rare occurrence and probably only in the early morning hours.

I would love to be able to use that line to power my 220v equipment. I would like to split it into 2 30 amp circuits. is that possible?

I know that some of the square d breakers can be double tapped but I am not sure that you can do that on the big 60 amp breakers.

Worst case scenario I will just have one 20amp 220 circuit but I would really love to make this work. Here is what I have come up with:

-- http://icftfsystemshome.blogspot.com/


17 replies so far

View toolie's profile

toolie

1774 posts in 1381 days


#1 posted 09-18-2013 01:22 AM

I would like to split it into 2 30 amp circuits. is that possible?

yes. if the 60A line from the main panel terminates at this heat pump, i’d run remove that line from the heat pump and use it to energize a 60A subpanel. then feed the heat pump and 3 more 220v circuits from the sub panel to wherever you want. it might not be possible to use power equipment when the heat pump is operating, but 220v tools use less amperage than 110v tools do.

-- there's a solution to every problem.......you just have to be willing to find it.

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Grandpa

3211 posts in 1428 days


#2 posted 09-18-2013 01:28 AM

Strip heat is what you are using the 60 amps for. If you have a heat pump it should operate off a 30 or 40 amp circuit and it should be separate from the 60 amp circuits I believe. Do as Toolie said and install a sub panel. You can power the sub panel with one of the 60 amp breakers then split it like you want from there. While it is true that 220V power uses half the amperage it uses it on 2 legs instead of one. All you really gain there is smaller wire can be used. You should be able to buy a 100 amp panel and breakers for $100 at HD. I did last year. got a Cutler Hammer.

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toolie

1774 posts in 1381 days


#3 posted 09-18-2013 01:49 AM

220V power uses half the amperage it uses it on 2 legs instead of one.

but they are not additive. a tool drawing 12A @ 220v does not take up 24A of line capacity.

-- there's a solution to every problem.......you just have to be willing to find it.

View jonah's profile

jonah

453 posts in 2051 days


#4 posted 09-18-2013 02:01 AM

Toolie is correct. Adding a 60A sub panel would allow you to install breakers for whatever you want. Realize, though, that you will never be able to use more than 60A downstream of that panel, regardless of whether its 120 or 240V. The advantage of using 240V, in this circumstance, is that you would be able to run more equipment at once than you could at 120V, since motors that can run at both voltages use roughly half the current at 240V.

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onesojourner

41 posts in 469 days


#5 posted 09-18-2013 02:02 AM

Thanks guys.

The hvac system is on 3 circuits. The outside unit unit is on one 30a the inside unit is on one 30a and the heat strips are on the 60a.

I should be able to use power equipment as long as I am not using the strips correct? The pump is on it’s own 30a circuit.

What is the best way to make a connection in 6awg wire?

-- http://icftfsystemshome.blogspot.com/

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Grandpa

3211 posts in 1428 days


#6 posted 09-18-2013 02:18 AM

You are thinking correctly. I rarely use the heat strips but I do live in southern Oklahoma. I would (if it is feasible) put my new sub panel near the air handler. Is it in the garage? If it is you can put your CB panel there and feed into it then you can make all connections inside that panel. If you install the sub panel near the main panel then do the same except you put in new wire from the 60 amp in the main to the sub panel then use the old wire from there to the heat. There are junction boxes for larger wire but they are expensive. I have a panel on the outside of my house that is no more than a junction box. I am not sure of the wire size. I would guess it to be 0000. It is huge. An electric company wired it. They took the buried cable and put it in one side of the panel and the new wire out the other side. I am sure it is costly to do that so if you can work around it with your breakers and panel then you would be money ahead.

View crank49's profile

crank49

3524 posts in 1723 days


#7 posted 09-18-2013 02:28 AM

Auxiliary strip heat, what you are calling backup heat I think, does not always switch in at full capacity.
You may have a unit with 12 to 15 KW of elements that come online in three stages.
If all elements are on, say it’s -40 degrees outside and someone left the door hanging open, they will use the entire 60 amp capacity of the 60 amp breaker in your main panel, so nothing left for the 220v circuits in the shop.

But if it’s only 25 degrees outside and you have the house buttoned up tight and well insulated it will get a little heat from the heat pump unit and may only kick in 1/3 of the strips, maybe 5 KW. That will use about 21 amps of the 60 amp capacity. the extra will be available.

So, yes you can do this, but not the way you drew it. Don’t use junction boxes to split circuits.

Hook it up the way Toolie described it.

Remove the 60 amp feed going to the heat pump auxiliary heaters and connect those wires to the input side of a sub panel. You can use what ever size panel you want as long as it is AT LEAST 60 amps. I’d go for a 100 amp if it were me, because they are only a couple dollars more than a 60 amp panel. Then install a 60 amp 2 pole (240 volt) breaker in the sub panel and run a new 60 amp feed back to the heat pump auxiliary heat unit. At this point you have however many breaker slots left in the sub panel for use in the shop. If it was an 8 slot panel you could hook up six 120 volt circuits or three 240 volt circuits, or what ever combination of those you want.

One other little detail; I would be sure to connect the shop’s lights to a separate circuit coming from the main panel and nothing else on that line but the lights. You might have your table saw and dust collector running and the heat pump decides to kick in with two banks of strip heat. That load will most likely kick the 60 amp breaker feeding your sub panel, but you won’t be left in the dark with a spinning saw blade.

-- Michael :-{| “If you tell a big enough lie and tell it frequently enough, it will be believed.” ― A H

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woodbutcherbynight

1311 posts in 1161 days


#8 posted 09-18-2013 02:38 AM

+1 for Crank49’s suggestion. Had a friend tie everything into a single 30 amp breaker, lights, outlets and a couple of saws all located in the basement. He got carried away one night and blew the breaker with nobody home and stuck in pitch black trying to weave his way around to the door. Not fun for him, but I did enjoy a good laugh when he called me over to help fix the problem.

-- Live to tell the stories, they sound better that way.

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onesojourner

41 posts in 469 days


#9 posted 09-18-2013 03:00 AM

grandpa, the unit is down in the basement right next to where the shop is going to be. We are in SW MO so our climate is not to different than yours. We will also being using our wood stove as the primary heat source and the house is icf, so it doesn’t get much tighter.

This is the panel I think I will pick up. I am not sure how the connections are made in furnace to the strips but there is a double pole 60 amp breaker in the furnace for those. I don’t know if I can remove those and still make the connection. I will have to get the cover pulled and look.

Alright so let me go over this once more time. I will pull the connection from the heat strips and attach it to something like THIS . Then Grab another 60amp breaker and run some more 6awg from that back to the heat strips. Then I still have room for 2 more 30amp breakers ? Then I can run 10awg all over my shop right?

-- http://icftfsystemshome.blogspot.com/

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onesojourner

41 posts in 469 days


#10 posted 09-18-2013 03:06 AM

Oh yeah and thanks for the tip on the lights. That is pretty much how I did all the rooms in the house. I kept the lights on separate circuits from the receptacle in the rooms. So if something does blow your not left in the dark.

-- http://icftfsystemshome.blogspot.com/

View woodbutcherbynight's profile

woodbutcherbynight

1311 posts in 1161 days


#11 posted 09-18-2013 03:13 AM

A lesson on lights from my service in the military. GLOWSTICKS work great when the power goes out. Simple to use, no mess, no chance of fire unless you set them on fire and they stay bright for 2-4 hours, moderate light from 4-6 hours and minor light thereafter till they die in 8-10 hours. For a good laugh throw a green one in a porta potty at a concert after dark and then hang around for the next few people to go in. They always comment. (laughing) OK so what else did we have to amuse ourselves in the desert of Iraq? (laughing)

-- Live to tell the stories, they sound better that way.

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crank49

3524 posts in 1723 days


#12 posted 09-18-2013 04:33 AM

Sounds good to me.

-- Michael :-{| “If you tell a big enough lie and tell it frequently enough, it will be believed.” ― A H

View Ralph's profile

Ralph

164 posts in 885 days


#13 posted 09-18-2013 01:37 PM

1+ woodbutcherbynight GLOWSTICKS
I always have my cell phone with me when working. In the dark it gives enough light to see around me!

-- The greatest risk is not taking one...

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Grandpa

3211 posts in 1428 days


#14 posted 09-18-2013 09:07 PM

Yes sir. You don’t want to remove the breakers from you air handler cabinet just the wiring. I think that is what you said. Then move on. If you use this box You are showing it is limited to the 6 spaces. You can have what you said but it will only be 220V. I think you have 110V from the home panel. Should be good to go. a little wire and get with it.

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toolie

1774 posts in 1381 days


#15 posted 09-18-2013 11:36 PM

personally, i’d get a larger subpanel wit more spaces for the future. when i fed my garage with 30A service, i thought, at th etime, i’m good from now on. shoulda run 60A. your 60A service is ok, i’d just prefer a panel with more spaces for as yet unseen needs.

-- there's a solution to every problem.......you just have to be willing to find it.

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