Adding additional breakers to main panel instead of sub panel?

[Mahonroy]

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.

 

[hj]

You have room for 4 two pole, 8 single, or 8 "split" breakers, (or some combination of the three types), and it makes no difference whether you put them in this box or elsewhere, they would still be "protected" by the main breaker. As for the wiring, as long as you do it "properly" any of the options are correct. Is that a damaged wire covering at the point where the yellow wire goes behind it?

 

[Sponsor]

 

[Reach4]

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....

It is normal for the breakers to add up to more than the main breaker. You have the main breaker to blow if all of the circuits start drawing near their max.

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.

If you use regular breakers rather than "tandem breakers", I think you can occupy all of the slots. If you use tandem breakers, then you have to read more about the box ratings. For that, you would want to find an actual model number on some label in that box.

3. In order to keep it to code,

I don't know about your conduit requirements.

However something that does look checking out: Your main breaker has a big white neutral going to the subpanel. There is also a bare protective ground wire, which are connected together only in the main box. OK so far.

But in the subpanel, you should not be using that bare wire to connect to the white wires. Your box may be perfectly OK with what it is doing. It probably is, but look it over

I am not an electrician. I cannot tell from the picture if all is OK. The wiring looks neat, and the person wiring probably did it all right.

 

[Jadnashua]

At (only) the main panel, ground and neutral will be bonded together. At your subpanel, the ground and neutrals should be separated.

 

[Mahonroy]

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!

 

[WorthFlorida]

When conduit is buried it usually has to be 18" below grade from the top of the conduit. PVC conduit where it can be impacted by something must be schedule 80. Sch 80 from the panel to the ground, Sch 40 under ground and then back to Sch 80 coming out of the ground or SCH 80 the whole way. For your short distance just run "home runs" from each circuit. You may need to add a pull box in the garage to transition from THHN to MC, etc. or just go with conduit everywhere. For conduit use THHN or THWN wire, you cannot run any wire in it's own jacket such as 12-3 NMC. Or you can run one large conduit or several smaller ones for each circuit. Without seeing the layout it's your call as to what would be the best way. Below is a chart for the maximum amount of wires in a pipe but try to go one size up for ease of pulling wires through. The cost difference between SCH 40 & 80, 1/2 or 3/4 inch conduit is very minimum.

http://www.williamsnashville.com/Technical_Data/Conduit_Fill_Table_PVC_40.html

 

[Mahonroy]

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 LB. On the other side of the LB (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 LB. Then a small run (like 1 foot) of NMB wire from this outside LB 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 LB 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.

EDIT: For some reason I had originally typed "FB" when I meant to type "LB".

 

[Stuff]

You can't splice wires in an LB. You would need to take the wires inside extending the conduit to the 3 gang box or mount a box on the outside.

 

[Jadnashua]

Conduit typically isn't considered waterproof, but is protection. So, you need wire rated for wet environment if running it underground.

 

[John Plunkett]

Really good info here. I am doing the same thing for my shop power. I don't need much current, I am just ma hobbiest. I do have one other question for this subject. In the main power panel, you have L1, L2, neutral and ground, with the neutral and ground sttached to the same point. On all subpanels you never short the neutral and ground again. That I do understand. If I add a 30 amp breaker to the main panel I will have three new wires to attachto the main and breaker. Black on the breaker, ground to ground, and does the neutral also attach to ground in the main? I only want 120 volts ourt of it.

 

[Jadnashua]

If you're adding a subpanel, you need a 4-wire cable. If you're tapping directly off of the breaker and actually want 30A, it gets a bit messier if you want 15A circuits...there are only 15 and 20A 120vac receptacles, so you cannot run that on a 30A circuit. If you ran that to a subpanel, you could put in two 15A breakers in it (and potentially more if those circuits won't all be exceeding the max current available). If you need more than 20A at 120vac, it would need to be a dedicated device, hardwired to a single-pole breaker. You'd use a double pole breaker to go to a subpanel.

You could get two 15A, 120vac circuits with a double-p0le breaker for a total of 30A at 120vac if you used a shared neutral...that would require a 3-wire cable, and you'd use neutral and L1 on one 'chain', and L2 and neutral on the second. What happens here is that the current on each circuit cannot exceed 15A, but because the L1 and L2 are opposite phases, they cancel in the neutral, so it never can exceed the 15A (so it's not 15+15 on the neutral wire). The breaker needs to be linked so if there's a fault on one side, it trips both 'channels' or with one 'side' off, there could still be current in the neutral of the other 'side'.

 

[Cacher_Chick]

Really good info here. I am doing the same thing for my shop power. I don't need much current, I am just ma hobbiest. I do have one other question for this subject. In the main power panel, you have L1, L2, neutral and ground, with the neutral and ground sttached to the same point. On all subpanels you never short the neutral and ground again. That I do understand. If I add a 30 amp breaker to the main panel I will have three new wires to attachto the main and breaker. Black on the breaker, ground to ground, and does the neutral also attach to ground in the main? I only want 120 volts ourt of it.

If your garage or shop is a detatched building, you may only run a single 15 or 20 amp circuit to it UNLESS you are going to install a subpanel in it. That subpanel would need to be fed by properly sized 4-wire feed and ground rods must be installed and wired at the sub.