Sub Panels: Is more better? or Cheaper?

[Matt Radtke]

In the next few months, I'll probably be upgrading my main panel from 100a/24 spots to a 200a/35 spot main panel. A big part of the driver is getting the headroom to expand my basement power. Both for my shop and extra living space. I have a couple options and I'm trying to figure out the best combination of panel(s) and location(s).

What I hope to end up with in the shop: 3 20a, 110v line for routers, hand held tools, and a HF dust collector. 1 20a or 15a circuit for lighting. 1 20a 220v (future 3HP cabinet saw) and 1 30a 220v (future 5HP jointer/planer combo) for future expansion. I want to get this "pretty close to right the first time," because I (read: my wife!) want to drywall finish the ceiling along the path of the runs. So I kind of only get one shot at this.

My original plan was to put a 100a panel in one spot very close to my main panel. (Main panel is in the garage.) Total run from the main panel to propose spot (which is in the storage room) would require only about 10'-15' of cable. Quick, simple, and everything is obvious, and I don't have to fight a giant service cable or long distances. Potential downside: that spot is about as far away as possible from the entry point into my shop. I'm estimate 30 feet from the subpanel to the closest outlet location in the shop and I'd have to drill through 3 joists to keep it out of the future drywalling. With 6 circuits, I could see that getting expensive quickly. And I haven't actually wired up the shop, just brought the power to the shop.

My second thought was put a 100a panel in a more central location close to my shop. The downside is now I have that whole run (30-45 feet) from the main panel to the sub panel. And I'd still have to go through three joists. The hole I would potentially have to drill to get gauge 1 wire and make a 90 degree turn worries me. Should I be worried? On the plus side, the utility room shares a wall with my shop, so I would literally only need to run cable cable 2 feet from the panel to my first outlet.

My third thought was to put two 60 amp panels in the basement, one at each location (storage room and utility room). 6-3NM cable is cheap enough and small enough to not break any backs during installation. Seems to solve the most problems, I'd only have to run one cable to the utility room, but I'd obviously need to buy 2 panels instead of 1, which might not end up saving me money.

Option 3a was daisy chaining option 1 and 3 together: 100a sub panel in the storage room, and a 60 sub-sub-panel in the utility room. Something about that seems bush league to me, but maybe I'm worrying about nothing. I also don't know if it's any better from just 2 60a panels.

Help?

[Chris Padilla]

6/3 is quite easy to work with and I see no issues spreading around a couple 60A panels regardless if they are sub or sub sub or sub sub sub. The electricity doesn't care and as long as you isolate ground from neutral, you should be fine.

The thing I don't know is if the cost is somewhat linear as the wire gauge increases. Having long runs of 12/2 or 14/2 shouldn't break the bank. In fact, you can run it all in 12/2 (even the 15 A stuff) if you want to reduce the loss a bit.

[Buck Williams]

Matt, check out the price of #2 SER cable, 3 - #2 aluminum conductors with a #4 bare ground, O.D. is about 3/4", should be no problem to drill and pull it through 2 x 4 studs. It's done all of the time most stick built apartment buildings have their 100 amp panels fed with this cable.

[Matt Radtke]

Matt, check out the price of #2 SER cable, 3 - #2 aluminum conductors with a #4 bare ground, O.D. is about 3/4", should be no problem to drill and pull it through 2 x 4 studs. It's done all of the time most stick built apartment buildings have their 100 amp panels fed with this cable.

Anything special handling required for the aluminum cable? My exposure to aluminum wiring is pretty much "OH GOD NO," but that's just normal stuff in the wall for outlets and the like.

[Chris Padilla]

I'm not a big fan of aluminum wiring even though it feeds the house sub-panel (100A, came with the house) at my place and feeds the stove (50A). It has a lower conductivity than copper which is why it needs to be larger to carry the same amount of current as copper. It does get a bad rap but it works just fine and it is cheaper. You just need to use the goop at the connecting points to prevent the oxidation that can cause problems. Still, I wouldn't use it. I just like good old copper. Each to their own.

[Jeff Duncan]

Personally I'd put the shop panel in the shop and run the cable to that. I would think you could get by with #2, but obviously you need to use whatever code requires. I just ran 3 gauge 4 wire for a sander and it's not that big. Probably fit through a 1-1/4" hole. 2 gauge would be larger but, your only running 2 wires and a ground so??? I will say it's a bit tough with bends, but you only have to do it once!

good luck,
JeffD

[Matt Radtke]

Personally I'd put the shop panel in the shop and run the cable to that. I would think you could get by with #2, but obviously you need to use whatever code requires. I just ran 3 gauge 4 wire for a sander and it's not that big. Probably fit through a 1-1/4" hole. 2 gauge would be larger but, your only running 2 wires and a ground so??? I will say it's a bit tough with bends, but you only have to do it once!

good luck,
JeffD

Well, 4 wires for a sub panel. Hot, Hot, Neutral, and Ground. Isolated ground at the sub panel and that jazz.

[Rollie Meyers]

Matt, check out the price of #2 SER cable, 3 - #2 aluminum conductors with a #4 bare ground, O.D. is about 3/4", should be no problem to drill and pull it through 2 x 4 studs. It's done all of the time most stick built apartment buildings have their 100 amp panels fed with this cable.

2 AWG aluminum is NOT suitable for 100A when used for a subfeed, for that purpose 90 ampere breaker has to be used.

[Matt Radtke]

2 AWG aluminum is NOT suitable for 100A when used for a subfeed, for that purpose 90 ampere breaker has to be used.

I was coming to the same conclusion, though 90a would probably be more than fine for my uses. Of course, 4/0 SER is cheap enough I could do that and be over built.

[Rod Sheridan]

Hi, I'm a big fan of multiwire branch circuits for home shops.

If you put in a 2 pole 20 ampere breaker with 12/3 wire it will supply all your 20A 240V receptacles and all your 120V 20A receptacles in your shop.

I have 4" square boxes every 5 feet along the wall with a 240V duplex and a 120V duplex. Covers all my shop machinery and portable power tools with one breaker.

I also have a separate 240V circuit for the cyclone.

There's no point running a bunch of circuits for a home shop................Regards, Rod.

[Matt Radtke]

Hi, I'm a big fan of multiwire branch circuits for home shops.

If you put in a 2 pole 20 ampere breaker with 12/3 wire it will supply all your 20A 240V receptacles and all your 120V 20A receptacles in your shop.

I have 4" square boxes every 5 feet along the wall with a 240V duplex and a 120V duplex. Covers all my shop machinery and portable power tools with one breaker.

I also have a separate 240V circuit for the cyclone.

There's no point running a bunch of circuits for a home shop................Regards, Rod.

While I I like the idea of use 12/3 for 110, I feel like a single circuit will come back to haunt me. And I have ambitions of a couple larger machines. The last thing I want to do is under-power, get that larger machine, and then have to tear out my ceiling to get more power run.

What big things? 3HP cabinet saw, 5HP Griz J/P Combo, and likely someday my father's vertical mill.

If I never upgrade past a HF dust collector, it seems possible that it plus a 3HP cabinet saw would draw more than 20amp on one circuit. By all means, convince me I'm wrong there and I'll scale back slightly.

[Chris Padilla]

Several years ago when copper was a lot cheaper, I just redid my entire garage with stranded #10 everywhere. I put in flex conduit and pulled the wires. I did the multiwire (Edison) for all my branch circuits as well. All my 30A were individually run back to the panel.

If you REALLY want to future-proof your circuits, run 10/3 everywhere or put in flex conduit so you can pull bigger wires later if needed. Cry once with a lighter wallet and sore fingers dealing with #10 but sleep well over the years knowing you can run any piece of equipment you want at any location you want.

Think about the items that will need their own circuits. You've listed a few: Dust Collector and Air Compressor are the two main ones as these are likely to run when you are running other items. Perhaps an air conditioner, heater, or secondary air filter might need its own circuit. Lights will be on their own for sure (or should...some suggest two separate circuits!). Things like a table saw, jointer, planer, jointer/planer combo, bandsaw, lathe (metal and/or wood) or a mill can technically be shared on a single 240V/30A or 240V/20A circuit.

[Rod Sheridan]

While I I like the idea of use 12/3 for 110, I feel like a single circuit will come back to haunt me. And I have ambitions of a couple larger machines. The last thing I want to do is under-power, get that larger machine, and then have to tear out my ceiling to get more power run.

What big things? 3HP cabinet saw, 5HP Griz J/P Combo, and likely someday my father's vertical mill.

If I never upgrade past a HF dust collector, it seems possible that it plus a 3HP cabinet saw would draw more than 20amp on one circuit. By all means, convince me I'm wrong there and I'll scale back slightly.

My major machines are 4 HP (saw/shaper, Jointer/planer), perfect for a 20 ampere branch circuit.

You'll need a separate circuit for the dust collector.

Regards, Rod.

[Matt Radtke]

Using 10/3 everywhere is not a bad plan and I'll have to think about that one.

And yes, I didn't even mention lighting because yes, it'll get its own circuit.

[Julie Moriarty]

In the next few months, I'll probably be upgrading my main panel from 100a/24 spots to a 200a/35 spot main panel.

I'd upgrade to a 200A, 40 space panel instead of a 36 space. The extra space will be there when you need it.

What I hope to end up with in the shop: 3 20a, 110v line for routers, hand held tools, and a HF dust collector. 1 20a or 15a circuit for lighting. 1 20a 220v (future 3HP cabinet saw) and 1 30a 220v (future 5HP jointer/planer combo) for future expansion. I want to get this "pretty close to right the first time," because I (read: my wife!) want to drywall finish the ceiling along the path of the runs. So I kind of only get one shot at this.

If I counted right, right now you need (4) single pole breakers and (2) 2-pole breakers. That's 8 spaces so you probably want a panel with 12-16 breaker spaces, or more. Since you're planning on drywalling the ceiling, run some feeders out to junction boxes you can access later, in a wall or ceiling that isn't drywalled. You'll have to do some looking into the crystal ball to decide what and where you might need the power in the future. At the very least, run two circuits to each location. You don't have to land them on breakers until you need them.

My original plan was to put a 100a panel in one spot very close to my main panel. (Main panel is in the garage.) Total run from the main panel to propose spot (which is in the storage room) would require only about 10'-15' of cable. Quick, simple, and everything is obvious, and I don't have to fight a giant service cable or long distances. Potential downside: that spot is about as far away as possible from the entry point into my shop. I'm estimate 30 feet from the subpanel to the closest outlet location in the shop and I'd have to drill through 3 joists to keep it out of the future drywalling. With 6 circuits, I could see that getting expensive quickly. And I haven't actually wired up the shop, just brought the power to the shop.

My second thought was put a 100a panel in a more central location close to my shop. The downside is now I have that whole run (30-45 feet) from the main panel to the sub panel. And I'd still have to go through three joists. The hole I would potentially have to drill to get gauge 1 wire and make a 90 degree turn worries me. Should I be worried? On the plus side, the utility room shares a wall with my shop, so I would literally only need to run cable cable 2 feet from the panel to my first outlet.

My third thought was to put two 60 amp panels in the basement, one at each location (storage room and utility room). 6-3NM cable is cheap enough and small enough to not break any backs during installation. Seems to solve the most problems, I'd only have to run one cable to the utility room, but I'd obviously need to buy 2 panels instead of 1, which might not end up saving me money.

Option 3a was daisy chaining option 1 and 3 together: 100a sub panel in the storage room, and a 60 sub-sub-panel in the utility room. Something about that seems bush league to me, but maybe I'm worrying about nothing. I also don't know if it's any better from just 2 60a panels.

Help?

Option 1 seems the worst. Get the panel closest to where you will be tapping it for power. It's also nice to have the panel in your shop in the event you trip a breaker, then it's a short trip to reset it.

Option 2 is what I'd go with. I don't know why you'd be worried drilling the joists unless you have something like 2x6 joists. I've drilled through 2x10s for 2" pipe with no problem. You just have to be towards the center of the joist. Inspectors around here will fail the job if holes are drilled too close to the bottom of the joist but allow for drilling very close to the top. I've never heard of any joist failing because of a hole drilled for electrical distribution. If you go with this option, get the largest 100A panel you can find.

Option 3 isn't unheard of but it can tax the first sub panel, depending on the loads distributed from there. On big jobs, we start with very large switchgear and distribute to subsequently smaller and smaller distribution panels until we finally get to something like a 200A, 120/208v panel. But all the wiring and breakers are sized properly. While Option 3 may not be bush league, it is a bit unusual in a residential application and you'd have to figure for the loads to make sure the sub panels, wire and breakers are properly sized.

Hope this helps.