Go Back  DoItYourself.com Community Forums > Electrical, AC & DC. Electronic Equipment and Computers > Electrical - AC & DC
Reload this Page >

Adding additional breakers to main panel instead of sub panel?

Adding additional breakers to main panel instead of sub panel?

Reply

  #1  
Old 04-04-17, 10:18 AM
M
Member
Thread Starter
Join Date: Feb 2017
Location: USA
Posts: 9
Received 0 Votes on 0 Posts
Adding additional breakers to main panel instead of sub panel?

Hey guys,
Let me describe the scenario first:
I have an attached garage that I am wanting to add additional circuits to:
1x 50 amp 220v
3x 20 amp 110v

On the outside of the garage there is a main panel that contains a single 200 amp breaker, and thats it. This feeds a sub panel that is inside the garage where all of the wiring for the house & garage resides.

I want to add the additional circuits receptacles pretty much on the other side of the wall of the main panel. So it got me thinking... instead of pulling 100 feet of wire from the sub panel in the garage, up into the attack and across the entire garage, and back down the wall on the other side.... why not just add the additional circuits to the main panel since all I would need to do is run 10 feet of wire to the other side of the wall?

Is this possible to do?

Here are some of my questions:
1. If I add breakers to the main panel, there would now be these breakers in the panel:
1x 200 amp breaker
1x 50 amp breaker
3x 20 amp breaker
So those extra breakers would be in parallel to the original 200 amp breaker. The entire sub panel is protected by the single 200 amp breaker, but what would be protecting the now 310 amps worth of breakers? Something doesn't seem right here....

2. How do I know how much additional breakers I can add to this main panel? Does this depend on the "amp service" that was installed for the house? Or capabilities of the main panel? I took some photos of the panel and I was not able to determine any of this.

3. In order to keep it to code, I am under the impression that I can use UV resistant water proof PVC conduit right out the side of the main panel, along the outside of the house (only like 10 feet) into a waterproof receptacle box that is mounted to the side of the house and sealed with silicone. On the other side of the wall would be another receptacle box, and below that would be all 4 of the new circuits. Is this a process that makes sense? Would it be better to run the conduit straight down and 12" into the dirt along the house, then span the 10 feet, then straight up into the receptacle box?

And just so you know, although I don't fully know all of the processes and codes, I do know how to be safe when working with mains power.

Thanks and any help/advice is greatly appreciated!

I uploaded photos of the main panel, the 2 stickers on the main panel, the main panel with the cover off, and the sub panel with the cover off.
Name:  20170403_185650.jpg
Views: 740
Size:  18.8 KBName:  20170403_195329.jpg
Views: 578
Size:  29.5 KBName:  20170403_195349.jpg
Views: 540
Size:  21.7 KBName:  20170403_185753.jpg
Views: 1601
Size:  32.3 KBName:  20170312_115653.jpg
Views: 2041
Size:  34.7 KB
 
Sponsored Links
  #2  
Old 04-04-17, 11:04 AM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
So those extra breakers would be in parallel to the original 200 amp breaker.
They would be fed and protected by the 200 amp breaker.
How do I know how much additional breakers I can add to this main panel?
You use actual load not breaker size.
I can use UV resistant water proof PVC conduit right out the side of the main panel, along the outside of the house (only like 10 feet) into a waterproof receptacle box that is mounted to the side of the house and sealed with silicone.
Yes. You would use individual THWN wires.You would need individual hots and neutrals for each circuit but only a single ground sized to the highest amp circuit.
I am wanting to add additional circuits to:
1x 50 amp 220v 3x 20 amp 110v
You have 120 volts and 240 volts not 110v and 220v.
 
  #3  
Old 04-04-17, 11:20 AM
M
Member
Thread Starter
Join Date: Feb 2017
Location: USA
Posts: 9
Received 0 Votes on 0 Posts
Thanks for the reply!

1. I don't understand how they would be fed and protected by the 200 amp breaker if the breakers are installed on the main panel in parallel to the 200 amp breaker. This does not seem correct.

2. Do they have to be individual THWN wires? Whats wrong with just using 12-2 UF-B, and 6-3 UF-B? One 240v receptacle and three 120v receptacles equals 13 wires total... thats a lot of individual wires to get mismatched when running those through conduit?
 
  #4  
Old 04-04-17, 12:06 PM
I
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,944
Received 42 Votes on 40 Posts
The bus bars beneath the main breaker are protected by the main. The bottom lugs are called feed-through lugs which power the indoor panel.

UF-B is too bulky to pull through conduit, and you would need two separate conduits due to the number of wires and temperature ampacity. Use one 3/4" conduit for the 50A circuit and one 1/2" or 3/4" conduit for the 20A circuits. You can mark individual wires with numbered stickers for identifications.
 
  #5  
Old 04-04-17, 01:16 PM
T
Member
Join Date: Nov 2007
Posts: 391
Received 0 Votes on 0 Posts
...Delete.......................
 
  #6  
Old 04-04-17, 02:28 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 15,113
Received 69 Votes on 59 Posts
Adding the breaker handles ratings is not the way to determine the load on a panel. It is a math exercise that gives a meaningless result. Many panels can have 4 to 5 times the main breaker rating worth of breakers..
 
  #7  
Old 04-04-17, 04:01 PM
A
Member
Join Date: Mar 2010
Location: USA
Posts: 3,976
Received 56 Votes on 54 Posts
The panel has a maximum amperage rating, stated on the sticker inside or on the door. The top breaker is probably equal to or less than the panel maximum rating in which case you don't have to worry about this.

The panel has a limit to the number of breaker handles, also stated on the sticker. You can have a regular breaker in every slot and not exceed this limit. You can also have a few tandem (single wide double handle or double wide 4 handle) breakers but not one in every slot.

When adding circuits or powering outbuildings, etc. you need to do a load analysis. The result may or may not require upgrading the panel to a larger amperage model and upgrading your service from the power company. The same load analysis rules are done whether you put new breakers in the main panel or in a subpanel.

A set of load analysis rules is in the NEC code book.

"... if the breakers are installed in the main panel in parallel with ..."

The various branch circuits with their individual breakers are in series with the main breaker. That is, when you flip off the main breaker or it trips, the branch circuit goes (all of them go) dead.

No problem having 2 to 3 times the amperage rating of the main breaker represented by the sum of the branch circuit breakers' ratings. You will never (at least I suppose you will never) have maximum loads on all branch circuits at the same time. Of course, if the sum of the actual amperes across all of the branch circuits exceeds the main breaker rating then the main breaker will tripl

The various branch circuits are in parallel with each other. So if one branch circuit's breaker trips, the other branch circuits remain live.
 

Last edited by AllanJ; 04-04-17 at 04:24 PM.
  #8  
Old 04-04-17, 05:52 PM
M
Member
Thread Starter
Join Date: Feb 2017
Location: USA
Posts: 9
Received 0 Votes on 0 Posts
Ok thanks guys for the great advice! I understand now... I was getting confused because I was thinking that 200 amp circuit breaker was just another breaker in the slot, and not the actual main that everything goes through first. Not sure why I was thinking that but its clear now. So this looks like it will work out great then!

One last question:
Instead of running conduit along the side of the outside wall (thinking it might be ugly) - could I instead run conduit straight down from the box to the ground/dirt, then run it horizontally 10 feet parallel to the house, then straight up and through the wall?
1. Do I need a junction box on both sides of the wall?
2. Are there any rules for the diameter of PVC vs the amount of wires going through?
3. Should I use 12-2 UF-B, and 6-3 UF-B, and just lay it 12" under the dirt (not inside PVC)? Or is it better to use single stranded wire through PVC the entire way?

Thanks again for all of the help!
 
  #9  
Old 04-04-17, 06:22 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
Yes you can bury the conduit. Minimum 18".
1. Do I need a junction box on both sides of the wall?
Not if you transition to cable in the box and go straight through the wall.
2. Are there any rules for the diameter of PVC vs the amount of wires going through?
There is maximum fill rate of 40%. There are chats to tell you how many wire per conduit size. Ben has already written:
Use one 3/4" conduit for the 50A circuit and one 1/2" or 3/4" conduit for the 20A circuits.
If the 50 amp circuit is for a 120/240 feed such a stove a stove you will need Two #6 black, One #6 white, and one #10 green. If it is feed to a 240 only such as a welder you will not need the white. The #10 green will be the shared ground for all the circuits.

For the three 120v/20a circuits you will need a #12 hot and a #12 neutral for each circuit. I'd suggest one each black, red, yellow (or blue). Use white for the neutrals.

If you run cables from the junction box all of your cable grounds connect to the #10 green.
 

Last edited by ray2047; 04-04-17 at 08:20 PM. Reason: Add info.
  #10  
Old 04-04-17, 07:12 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 15,113
Received 69 Votes on 59 Posts
The burial depth is greater than 12" for all circuits greater than 20 amps at 120 volts. Your runs would also need to be protected going into and coming out of the ground.
 
  #11  
Old 04-17-17, 09:05 PM
M
Member
Thread Starter
Join Date: Feb 2017
Location: USA
Posts: 9
Received 0 Votes on 0 Posts
So here is what I came up with. Mind letting me know if I am missing anything?

I am going to use a single 1" schedule 80 PVC conduit running from the main panel on the outside wall, straight down to the dirt - then 2 feet under the dirt, along side the house, then back up the wall into a FB. On the other side of the FB (inside the garage now) will be a 3 gang box, then closer to the floor will be an additional box for the 240v receptacle.

The plan is to run THHN or THWN wire from the main panel through the conduit, and have it terminate in the outside FB. Then a small run (like 1 foot) of NMB wire from this outside FB to the 3 gang box on the other side of the wall (the 3x 20 amp circuits will terminate here at their corresponding receptacles). As for the 50 amp circuit, the wires will be 1 foot of NMB from the outside FB to the 3 gang box, then from the 3 gang box down to the corresponding receptacle near the floor.

It looks like the total wire length will be approximately 30 feet.

As far as the number of wires allowed in the 1" sch80 PVC conduit, there will be 4x 6AWG THHN wires for the 50 amp 240v circuit (2x hot, 1x neutral, 1x ground), and there will be 6x 12AWG wires for the 3x 20 amp circuits (3x hot, 3x neutral). It looks like I can use the 6AWG ground for everything, and tee off that ground in either of the receptacles. From what I can tell, these 10 wires should be fine to run through 1" conduit.

Thanks again guys for the great advice! Please let me know if there is something I missed, or if there is a better way of doing something.
 
  #12  
Old 04-17-17, 10:29 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
Minimum burial depth is 18 inches. You can probably use schedule 40.
 
  #13  
Old 04-18-17, 02:08 AM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 15,113
Received 69 Votes on 59 Posts
You will not be able to splice in the LB.

It would be better to run a feeder and set another panel in the garage.
 
  #14  
Old 04-18-17, 07:14 AM
B
Member
Join Date: Oct 2008
Posts: 1,312
Received 0 Votes on 0 Posts
FYI - Someone did some GOOD PLANNING AHEAD when installing those breaker panels. Plenty of extra slots in both panels to add more stuff!
 
Reply
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


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: