Do I Need A Sub Panel Here? - Electrical - Page 2 - DIY Chatroom Home Improvement Forum


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Display Modes
Old 04-20-2011, 10:58 AM   #16
Lost..
 
Join Date: Oct 2009
Location: AL
Posts: 289
Rewards Points: 268
Default

Do I need a sub panel here?


Quote:
Originally Posted by rjniles View Post
You do understand that every other slot in the panel feeds from opposite taps of the POCO's center tapped transformer (Call in phrase A & phase B -- not really but it works for explanation). L1 & L2 is a better terminology. L1 to neutral is 120 volts, L2 to neutral is also 120 volts, L1 to L2 is 240 volts.

The 1" wide slots down each side of the panel are wired as L1, L2, L1, L2, L1, etc. A regular 2" wide 2 pole breaker bridges L1 & L2 and you get 240 volts. A 1" wide 2 pole mini breaker brides the bottom of L1 and the top of L2(or the bottom of L2 & the top of L1). Bridging both legs it provides 240 volts. To utilize the panel fully, you install single pole minis above and below the mini 2pole.
Yes - this is what i meant when i tried to explain it. Thank you so much! You explained it alot better than I did.

So I guess this solves the problem of whether or not I will have to add a sub panel at the main panel.

Now I can focus on the other issues

One last thing though..Someone mentioned somewhere in my couple of days of research that code no longer allows tandem / half sized breakers or something like that. Will doing this - what we are talking about here - abide by code?

Advertisement

J S Machine is offline   Reply With Quote
Old 04-20-2011, 11:23 AM   #17
mem
Member
 
Join Date: Dec 2010
Location: Central Ohio
Posts: 226
Rewards Points: 154
Default

Do I need a sub panel here?


Regarding your schematic J S, personally I would run the lights off a separate 15 amp circuit from the outlets. Run the outlets from their own 20 amp, or better yet two, circuits. You can still switch them if you like, but I don't understand why. You won't be left in the dark if something blows and maybe save some cash on the lighting hardware.
mem is offline   Reply With Quote
Old 04-20-2011, 11:30 AM   #18
Lost..
 
Join Date: Oct 2009
Location: AL
Posts: 289
Rewards Points: 268
Default

Do I need a sub panel here?


Quote:
Originally Posted by mem View Post
Regarding your schematic J S, personally I would run the lights off a separate 15 amp circuit from the outlets. Run the outlets from their own 20 amp, or better yet two, circuits. You can still switch them if you like, but I don't understand why. You won't be left in the dark if something blows and maybe save some cash on the lighting hardware.
Yes the more I consider it the better it sounds. It won't cost me that much more to run a seperate circuit if I have a sub panel right there in the shop. With a 50amp breaker for the welder and two single pole breakers, I should be good. Lights on one single pole breaker and the plugs on the other.
J S Machine is offline   Reply With Quote
Old 04-20-2011, 11:48 AM   #19
A "Handy Husband"
 
rjniles's Avatar
 
Join Date: Feb 2007
Location: South Carolina Low Country
Posts: 4,241
Rewards Points: 2,392
Default

Do I need a sub panel here?


Quote:
Originally Posted by J S Machine View Post

One last thing though..Someone mentioned somewhere in my couple of days of research that code no longer allows tandem / half sized breakers or something like that. Will doing this - what we are talking about here - abide by code?
The panel is listed for a maximum number of circuit (each pole counts as a circuit). As long as you do not exceed that count, you are NEC compliant. NEC does not ban half size breakers.

You panel appears to be a 20 space, 40 circuit panel. You have 38 circuits installed in 19 spaces. If you install the mini 30 amp 2 pole breaker as we discussed, your panel would be full. It would be a code violation to remove one of the full size 2 pole breakers to add more minis (you would exceed the 40 circuit limit.
__________________
Location:
Coastal South Carolina
rjniles is offline   Reply With Quote
Old 04-20-2011, 11:59 AM   #20
Lost..
 
Join Date: Oct 2009
Location: AL
Posts: 289
Rewards Points: 268
Default

Do I need a sub panel here?


Quote:
Originally Posted by rjniles View Post
The panel is listed for a maximum number of circuit (each pole counts as a circuit). As long as you do not exceed that count, you are NEC compliant. NEC does not ban half size breakers.

You panel appears to be a 20 space, 40 circuit panel. You have 38 circuits installed in 19 spaces. If you install the mini 30 amp 2 pole breaker as we discussed, your panel would be full. It would be a code violation to remove one of the full size 2 pole breakers to add more minis (you would exceed the 40 circuit limit.
I understand. So as long as I stay within the 40 circuit range I'm good as far as NEC requirements go.

Thanks for your help and sorry it took me so friggen long to understand what you were getting at
J S Machine is offline   Reply With Quote
Old 04-20-2011, 02:11 PM   #21
Licensed Pro
 
Join Date: Mar 2007
Location: SC
Posts: 1,546
Rewards Points: 1,000
Default

Do I need a sub panel here?


Quote:
Originally Posted by rjniles View Post
The panel is listed for a maximum number of circuit (each pole counts as a circuit). As long as you do not exceed that count, you are NEC compliant. NEC does not ban half size breakers.

You panel appears to be a 20 space, 40 circuit panel. You have 38 circuits installed in 19 spaces. If you install the mini 30 amp 2 pole breaker as we discussed, your panel would be full. It would be a code violation to remove one of the full size 2 pole breakers to add more minis (you would exceed the 40 circuit limit.
That panel is designed to accept all half size breakers, a 20 space/40 circuit panel. It only has 28 circuits now, so by design, you could replace all the full sized db breakers with half size and add 12 more circuits. Not really advisable, but possible.
__________________
"Life is hard. Life is harder when you're stupid." John Wayne
HouseHelper is offline   Reply With Quote
The Following User Says Thank You to HouseHelper For This Useful Post:
J S Machine (04-20-2011)
Old 04-20-2011, 03:07 PM   #22
Lost..
 
Join Date: Oct 2009
Location: AL
Posts: 289
Rewards Points: 268
Default

Do I need a sub panel here?


So lets say I have the sub panel in the shop. I need a 50amp breaker in there for the welder, a 20amp for the plugs, and a 20amp for the lights. that is a total of 90amps. I know 20amp is kind of overkill for the lights. would a 15 do it, or would it be better to go ahead and put a 20 in case I add more light later?

Does this mean I would need a 90amp breaker at the main panel? Or would it be best to go ahead and put a 100amp?

If there is a 90 or 100 amp breaker at the box (depending on which one is advised that I use) would I run wire through my conduit according to that size? In other words would I need wire rated for 100amps?
J S Machine is offline   Reply With Quote
Old 04-20-2011, 03:57 PM   #23
A "Handy Husband"
 
rjniles's Avatar
 
Join Date: Feb 2007
Location: South Carolina Low Country
Posts: 4,241
Rewards Points: 2,392
Default

Do I need a sub panel here?


Quote:
Originally Posted by HouseHelper View Post
That panel is designed to accept all half size breakers, a 20 space/40 circuit panel. It only has 28 circuits now, so by design, you could replace all the full sized db breakers with half size and add 12 more circuits. Not really advisable, but possible.

HH is correct I added 10 for the 5 2 pole breakers and 18 for the half size single pole and came up with 38? DOH! You are only using 28 circuits and could install more half size breakers. Sorry for the misinformation.
__________________
Location:
Coastal South Carolina
rjniles is offline   Reply With Quote
Old 04-20-2011, 04:08 PM   #24
A "Handy Husband"
 
rjniles's Avatar
 
Join Date: Feb 2007
Location: South Carolina Low Country
Posts: 4,241
Rewards Points: 2,392
Default

Do I need a sub panel here?


Quote:
Originally Posted by J S Machine View Post
So lets say I have the sub panel in the shop. I need a 50amp breaker in there for the welder, a 20amp for the plugs, and a 20amp for the lights. that is a total of 90amps. I know 20amp is kind of overkill for the lights. would a 15 do it, or would it be better to go ahead and put a 20 in case I add more light later?

Does this mean I would need a 90amp breaker at the main panel? Or would it be best to go ahead and put a 100amp?

If there is a 90 or 100 amp breaker at the box (depending on which one is advised that I use) would I run wire through my conduit according to that size? In other words would I need wire rated for 100amps?
That is not the way to size the subpanel breaker. Adding the sum of the installed breakers is meaningless; try adding up the breakers in your main panel to prove how meaningless.
You need to calculate the expected loads and size the sub based on that. With a 50 amp breaker and a couple of 20 amps for lights and receptacles, I think 60 amps is plenty. That is the size breaker in the main panel. You can use a 100 amp in the sub as you can usually buy a packaged deal with a 100 amp main and a number of 20 amps cheaper than buying the individual parts.
Here is a GE for $49 (I show GE because that is what you have as a main, but you can use any brand you like.
http://www.homedepot.com/h_d1/N-5yc1...atalogId=10053
__________________
Location:
Coastal South Carolina
rjniles is offline   Reply With Quote
Old 04-20-2011, 04:18 PM   #25
Lost..
 
Join Date: Oct 2009
Location: AL
Posts: 289
Rewards Points: 268
Default

Do I need a sub panel here?


Quote:
Originally Posted by rjniles View Post
That is not the way to size the subpanel breaker. Adding the sum of the installed breakers is meaningless; try adding up the breakers in your main panel to prove how meaningless.
You need to calculate the expected loads and size the sub based on that. With a 50 amp breaker and a couple of 20 amps for lights and receptacles, I think 60 amps is plenty. That is the size breaker in the main panel. You can use a 100 amp in the sub as you can usually buy a packaged deal with a 100 amp main and a number of 20 amps cheaper than buying the individual parts.
Here is a GE for $49 (I show GE because that is what you have as a main, but you can use any brand you like.
http://www.homedepot.com/h_d1/N-5yc1...atalogId=10053
Ok I see. So use a 60amp breaker in the main panel. Then when I get to the sub panel out in the shop, buy something like what you are saying. For some reason I forgot that the panel would have a main breaker. I didn't know it would be cheaper just to buy a panel with several breakers already installed. Thanks for that tip.

However, I am a bit confused.

If I have a 60amp breaker on the main panel at the house, how would I have a 100 amp breaker at the sub panel? I'm sorry to not understand, but I don't see why I would have a smaller breake rat the main panel, and one of larger size at the sub panel.

I'm sure you are correct, I'm just looking for why that is. If that is the case does that mean I can use wire adequate enough to handle only 60amps instead of 100 between the main panel and sub?

Ok this may be the dumbest question of all-

If I need three wires and a ground going to the shop, where will they connect in the main panel???

I know that a two pole breaker has a spot at each pole for a wire. then there is a ground strip in there correct? What about the third hot wire (or would this be the neutral)?
J S Machine is offline   Reply With Quote
Old 04-20-2011, 04:53 PM   #26
mem
Member
 
Join Date: Dec 2010
Location: Central Ohio
Posts: 226
Rewards Points: 154
Default

Do I need a sub panel here?


I'm with you J S, a little confused. I'm sure rj is correct, but one would think that if the sub had a 100 amp main breaker then the wire feeding it would also need to be rated at 100 amps, even if the whole thing is fed by only a 60 amp breaker at the main panel.

And, yes, the third wire would be your neutral line. There is also some special considerations to be aware of regarding bonding at the sub. I'll let the pros explain it, or you can search the forums for sub panel bonding--it's a hot topic.
mem is offline   Reply With Quote
Old 04-20-2011, 04:54 PM   #27
A "Handy Husband"
 
rjniles's Avatar
 
Join Date: Feb 2007
Location: South Carolina Low Country
Posts: 4,241
Rewards Points: 2,392
Default

Do I need a sub panel here?


O

However, I am a bit confused.

If I have a 60amp breaker on the main panel at the house, how would I have a 100 amp breaker at the sub panel? I'm sorry to not understand, but I don't see why I would have a smaller breaker at the main panel, and one of larger size at the sub panel.

The breaker in the sub is merely a disconnect, it can be any size from 60 up (assuming a 60 amp in the main). It is just the cheapest way to go is buying that combo package.

I'm sure you are correct, I'm just looking for why that is. If that is the case does that mean I can use wire adequate enough to handle only 60amps instead of 100 between the main panel and sub?

Yep, size your feeder to the supply breaker, in your case 60 amp.

Ok this may be the dumbest question of all-

If I need three wires and a ground going to the shop, where will they connect in the main panel???

I know that a two pole breaker has a spot at each pole for a wire. then there is a ground strip in there correct? What about the third hot wire (or would this be the neutral)?

2 hot legs on the 60 amp breaker, neutral on the neutral bar, ground on the ground bar. In you main panel the ground and neutral may be the same bar. But they must be kept separate in the sub panel.


I know the next question will be what type/size wire. First tell us how you plan to get from the house to the garage. Buried conduit (18" depth) or direct burial (24" depth)?
__________________
Location:
Coastal South Carolina
rjniles is offline   Reply With Quote
The Following User Says Thank You to rjniles For This Useful Post:
mem (04-20-2011)
Old 04-20-2011, 05:01 PM   #28
Lost..
 
Join Date: Oct 2009
Location: AL
Posts: 289
Rewards Points: 268
Default

Do I need a sub panel here?


I'm not exactly positive on this, but for some reason I feel like direct burial cable will be more expensive per foot than regular THHN wire.

I also feel like individual wires may be cheaper than one all inclusive cable. In other words - four seperate wires (3 hots and ground), instead of something like romex type cable. Again i could be wrong.

I don't know the specific code, but I would imagine that it will have to be placed in pvc conduit. From what I have been reading, it is good to just go ahead an put it in conduit, and up size the conduit from what is required while you are at it, so there is room for further expansion if needed.

That being said, I'm sure it will be put in conduit.
J S Machine is offline   Reply With Quote
Old 04-20-2011, 05:02 PM   #29
mem
Member
 
Join Date: Dec 2010
Location: Central Ohio
Posts: 226
Rewards Points: 154
Default

Do I need a sub panel here?


I got it now! The main on the sub is merely a disconnect and the breaker at the main will protect the feeder cable. Thanks rj.
mem is offline   Reply With Quote
Old 04-20-2011, 05:16 PM   #30
mem
Member
 
Join Date: Dec 2010
Location: Central Ohio
Posts: 226
Rewards Points: 154
Default

Do I need a sub panel here?


Quote:
Originally Posted by J S Machine View Post
I'm not exactly positive on this, but for some reason I feel like direct burial cable will be more expensive per foot than regular THHN wire.

I also feel like individual wires may be cheaper than one all inclusive cable. In other words - four seperate wires (3 hots and ground), instead of something like romex type cable. Again i could be wrong.

I don't know the specific code, but I would imagine that it will have to be placed in pvc conduit. From what I have been reading, it is good to just go ahead an put it in conduit, and up size the conduit from what is required while you are at it, so there is room for further expansion if needed.

That being said, I'm sure it will be put in conduit.
I don't think you are allowed to put romex inside a conduit anyway. Also, make sure the wire you use is THWN or dual rated THHN/THWN. Can't use straight THHN outdoors or underground as it is not waterproof.

And while I was at it, I'd just put in the 100 amp cable now for future expansion, unless you think you'll have a use for the 60 amp after the upgrade. You can still feed it with a 60 amp breaker at the main panel for now.

Advertisement

mem is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Panel cleanup gdoucette Electrical 5 06-26-2010 03:01 PM
Sub Panel SoxFan Electrical 2 12-02-2008 11:16 AM
Extending Old Main Circuit Panel lkpowell Electrical 4 10-23-2008 03:15 PM
Installing new (service?) breaker panel and generator panel Nhrafan Electrical 6 04-01-2008 04:03 PM
turn main panel into a sub panel? tikicarver Electrical 2 01-24-2008 08:37 AM




Top of Page | View New Posts