Anyone install an subpanel in their workshop?

[Tim Dorcas]

I have 1 15 amp circuit that powers the entire garage. Yes. I have tripped the circuit. Too many times in fact. It will cost me $800 to $1200 to get someone to run a line for the subpanel and a couple of circuits. OR I could do it myself. It looks like a fairly straight shot to the garage without digging up anything or destroying multiple walls.

Is it doable? Is it reasonable to think a "Handy" man can do it?

Tim

[Don Baer]

I have 1 15 amp circuit that powers the entire garage. Yes. I have tripped the circuit. Too many times in fact. It will cost me $800 to $1200 to get someone to run a line for the subpanel and a couple of circuits. OR I could do it myself. It looks like a fairly straight shot to the garage without digging up anything or destroying multiple walls.

Is it doable? Is it reasonable to think a "Handy" man can do it?

Tim

yes you can do it. Not that hard as long as you plan it our or maybe all you need to do is install a few more circuits from you main panel. In order to advise you we need more information. What panel space is avaible in your existing main. What laods/tools are you planning to connect? You might be fine with running a couple of 220V runs and a couple of 11V circuit or you might neeeed a sub panel or you might need to upgrade your service. To quote an older movie we need "Input"

[Alex Shanku]

I was in the same boat. I pulled the existing wire, ran 4 pieces of 8ga to a subpanel, and then wired a 220v outlet and a bunch of 110v

[Cecil Arnold]

Another thing you might consider, if you are not comfortable doing wiring. You might rough in all the circuits, stick the sub panel in, and do everything you feel okay with, then find an electrician who might be interested in making a couple of extra $$ to cut it all in for you.

[Tim Dorcas]

To answer some earlier questions....

I have a 125 Amp panel with 6 slots available.

The biggest thing I have at the moment is my table saw. While it's running at 110 now, I want to switch to 220. I need to be able to run my dust control unit at the same time. Then I have the normal assortment of power tools.

The run to the garage is about 25 feet.

I don't necessarily think I absolutely need a subpanel. Just trying to think ahead.

Any and all advice is welcome.

Tim

[Don Baer]

OK time,
Thinking ahead. You are a one mane shop so you will only be running one machine at a time (Except for the DC) right? Not knowing the size of the DC I'd look at two alternative, keeping in mind with a 125 AMP service you still need to supply the house.
Option one
2 - 220 Volt circuits (20 amp)for DC and any other bog loads + 2 110 Volts circuits for recepticles (15 amps each)
Or Option two
1 new 60 amp sub panel and repeat step one for your loads. I opt for option 1

There are some benefits for option 1 but since your gonna be maxed out the only benefit I can see is more space in the main for additonal circuit should you plan on adding them later.

[Andy Hoyt]

Whatever you do - include a subpanel in the shop.

Makes life really easy down the road when you want to change something.

[Brad Olson]

I did it myself, pretty easy, just make sure you read up and get a permit.

Note that copper wire prices are wicked expensive. I don't know if prices will come down or not, but you feeder wire will probably set you back a lot of $$ depending on how long the run is. Probably $3 per foot if you use copper.

["Gary Brewer"]

Hello Tim: Fine Homebuilding No. 154 ( April, 2003 ) has an excellent article on wiring subpanels. The article starts on page 96. Take a look at it. It will help prevent mistakes.
Gary

[Norman Hitt]

IMHO any space used for a shop should have it's OWN subpanel, then you can wire anything in there anywhere anytime the need arises and with very little hassle. Another advantage is that you can leave your current ceiling light on it's present circuit with it's breaker in the house panel, and then wire any other lights off the subpanel, then should for some reason you trip the subpanel breaker with a tool running, the one ceiling light that is on the house panel will still be on and not leave you in the dark with a tool/blade running. It will also leave more spaces free in the house panel. The last advantage is that you only have to pull the three subpanel cables + bare ground wire from the house panel to the sub panel instead of all those wires for the different circuits from the house panel to the shop. It just seems like a much better setup IMHO.

Note: The bare ground wire between the house panel and the sub panel may or may not be required where you are, but the local folks here require it to eliminate something I think they call a looped ground, (or something like that).

[Alan DuBoff]

IMHO any space used for a shop should have it's OWN subpanel, then you can wire anything in there anywhere anytime the need arises and with very little hassle.I don't get this. Tim stated that he has 6 slots available. He didn't state how much amps total on the breakers in the panel already. With 6 slots, and especially if the panel is in the garage, what is the advantage of running a seperate panel, it will go to the same 125A panel he has. Since he has 6 slots, he can do quite a bit in that panel.

I would think better would be to install a new breaker, run wire to spec, and add a disconnect with slo-blo fuses so that the circuit is protected. That's what I did in my shop, and I only have 1 slot left, which actually has a breaker and outlet on it, I just don't use it that I know of.

I do have another panel running off of it, for my office in my backyard, and it has 3 breakers in it. I can't do anything much more, other than the 1 circuit that isn't used (was for the washer/dryer, and it is 240v), so that will turn into a new circuit in the garage. I could remove that breaker and add to the other panel, but my 125A is pretty much max'd out per amount of amps on it. I'll need to pull another 125A if I ever want to have more power.

Best advice is to get someone that knows what they're doing as far as electrical. If that is a friend that you trust, that works, or if that is a contractor, that works also. Just make sure it's wired correctly.

If 6 slots won't take care of his shop, well, sure get another panel...but I'm not sure I see the advantage other than spending more $$$s, when there's 6 slots available. Tim must have more amps he can use if there's 6 slots available. Unless he has some mammoth panel to begin with.

[Rob Russell]

Alan,

The advantage to a subpanel is that you have the ability to add circuits in that remote location without taking up slots in the main panel or running conductors all the way back to the main panel.

FYI, the number of open slots in a panelboard has nothing to do with the total load that panelboard is servicing. Likewise, you don't just add up the value of all the breakers or fuses in a panelboard and call that your load either, because all those circuits are not likely to be running at their respective limits.

Norman,

The reason that 240v subpanels have 4 conductors (2 hots, neutral, grounding) is because of the NEC bonding rules. There is a whole section of the NEC dedicated to Grounding - Article 250. One rule is that the neutrals and equipment grounding conductors are connected at one and only one point, and that point is the "service equipment". That's also where the grounding electrode system is tied in (connections to water pipes, ground rods and rebar in foundations).

For most of us, the service equipment is our main panel. After the service equipment, the neutral and equipment grounding conductors are separate and the neutral is "isolated", meaning it is not connected to the metal case of panel and is completely insulated from the panel. The neutral and grounding conductors have separate buss bars they connect to, where in the service equipment all the conductors can land on the same buss bars. It is possible to have your main panel wired as a subpanel. If your meter and service disconnect is a ways away from your main panel, it's quite likely that your bonding point is at the disconnect and your main breaker panel is run as a subpanel with separate and isolated neutral and equipment grounding conductors.

Rob

[Russ Filtz]

One other tip, use at least 1" conduit for the subpanel run, no matter what the code or anyone says! I tried 3/4" on mine, but due to some bends between pull points it wouldn't go through (even with plenty of lube). Pulled so hard I worried about damage to the wires.

Had to scrap everything and start over with new copper and 1"! Went much easier that time. The 4-wires is correct. You have to break off a tab inside the subpanel connecting the ground & neutral bus bars.

[Rob Russell]

One other tip, use at least 1" conduit for the subpanel run, no matter what the code or anyone says! I tried 3/4" on mine, but due to some bends between pull points it wouldn't go through (even with plenty of lube). Pulled so hard I worried about damage to the wires.

Had to scrap everything and start over with new copper and 1"! Went much easier that time. The 4-wires is correct. You have to break off a tab inside the subpanel connecting the ground & neutral bus bars.

Russ,

What size subpanel did you run and what did you use for conduit?

Rob

[Wes Billups]

Alan,

The reason that 240v subpanels have 4 conductors (2 hots, neutral, grounding) is because of the NEC bonding rules. There is a whole section of the NEC dedicated to Grounding - Article 250. One rule is that the neutrals and equipment grounding conductors are connected at one and only one point, and that point is the "service equipment". That's also where the grounding electrode system is tied in (connections to water pipes, ground rods and rebar in foundations).

For most of us, the service equipment is our main panel. After the service equipment, the neutral and equipment grounding conductors are separate and the neutral is "isolated", meaning it is not connected to the metal case of panel and is completely insulated from the panel. The neutral and grounding conductors have separate buss bars they connect to, where in the service equipment all the conductors can land on the same buss bars. It is possible to have your main panel wired as a subpanel. If your meter and service disconnect is a ways away from your main panel, it's quite likely that your bonding point is at the disconnect and your main breaker panel is run as a subpanel with separate and isolated neutral and equipment grounding conductors.

Rob

Rob, I am a couple days away from installing a sub panel in my basement shop. I purchased a 100 amp 12 slot panel from HD. If I understand you correctly I should pull a four conductor wire back to my main panel and terminate the neutral and ground on the appropriate buss bars. I was planning on running another bare copper to the water line just as the main panel but it sounds like that is not required.

Two questions;
I was thinking about only running a 60 amp breaker to the sub panel but am wondering if I should just go with the 100 amp while I'm at it?
Does the supply line to the sub panel need to be in conduit if the entire run will be covered with drywall?

I have 200 amp service to the house so I think either size is acceptable.

Thanks,
Wes billups

[Lars Thomas]

Tim must have more amps he can use if there's 6 slots available.

I must have more money, I still have checks.

[Paul Zonneveld]

Tim I wired my own garage with a subpanel more than two years ago. I had done some wiring in the past so I wasn't completely unfamiliar with wiring and electrical circuits. One good suggestion I have is to visit the local library. I managed to obtain two helpful books, one by Stanley and the other I forget who wrote it, but both contained a lot of helpful pictures and wiring diagrams that explained the whole process. I have essentially installed a 100amp breaker into the main house panel and ran that over into the sub-panel. The reason I used the subpanel is that I can cut power to the shop and lock the panel up (protects the kids) without messing with the main panel (which is outside). I of course like many others overdid it a bit and have 4 4gang outlet boxes (20 amps each) and two 220 lines (one 30amp and one 20 amp). One for the welder and plasma cutter and the other for the table saw. The books gave me some of the confidence I needed to tackle the job. I also used that blue plastic conduit (which requires no bending) and just ran it along the ceiling to the areas I wanted it. The hardest part for me was running the big wires from the subpanel over to my main panel and making those connections. The connections through the wall must be water tight as well and the conduit you run the wires through must have a downward facing loop in them to prevent water from running along the conduit and into the wall. The loops will allow the water to drip off the conduit before reaching the wall. The books explained all of this rather well though. The wires for the subpanel are big and thick and rather hard to move around and get into the breaker and ground and neutral bars. It also gives you a good view at how well the electrician did at wiring your house. How neat are the wires organized in the panel.

[jeremy levine]

Rob, ...I was planning on running another bare copper to the water line just as the main panel but it sounds like that is not required.

...

Don't, this will violate most elec. codes

[Richard Niemiec]

Tim: I've wired my shop in two different houses, and the 3 best things I ever did was: 1. Put a subpanel in the shop, 2. buy the Taunton Press book "Wiring a House" by Rex Cauldwell and 3. buy the Taunton Press book "Wiring a House" by Rex Cauldwell.

I cannot say enough about how much Rex's book helped. It is clear, direct, and very understandable and takes you through the process.

RN

[Jim Becker]

I think that wiring up your own sub-panel is a fine idea, particularly if you invest in an hour of a qualified electrician's time to check your work if you are not experienced and also potentially do the final connection to the main panel.

[Rob Russell]

Rob, I am a couple days away from installing a sub panel in my basement shop. I purchased a 100 amp 12 slot panel from HD. If I understand you correctly I should pull a four conductor wire back to my main panel and terminate the neutral and ground on the appropriate buss bars. I was planning on running another bare copper to the water line just as the main panel but it sounds like that is not required.

Two questions;
I was thinking about only running a 60 amp breaker to the sub panel but am wondering if I should just go with the 100 amp while I'm at it?
Does the supply line to the sub panel need to be in conduit if the entire run will be covered with drywall?

I have 200 amp service to the house so I think either size is acceptable.

Thanks,
Wes billups

Wes,

A couple of things:

I wouldn't put in a 12-slot panelboard for a subpanel - I'd put in at least a 20 slot panel. The cost difference between a 12 and 20 slot panelboard is minimal - probably less than $20. It might seem like plenty right now, but you'd suck up half of the 12 slots with (3) 240v circuits for a tablesaw or other machine, dust collector and decent compressor on its own circuit. Add another 240v machine that needs a different size circuit and you're down to 4 circuits. That doesn't leave many open slots, especially when the welding bug bites and you want to put in a 240v/50A circuit for a welder.
You must, not should, run a 4-conductor supply to the subpanel. The neutral buss/conductors in your subpanel must be isolated from the grounding bus/conductors. You need to make sure that the bonding screw is NOT installed. That last thing should be pretty easy - it's a green screw that connects the neutral buss to the panelboard housing or the grounding buss and, in many cases, is a screw in a little plastic bag that would have to consciously install. When you land the neutral and grounding conductors in your main panel, you'll be able to see whether the neutrals and grounding conductors are split there or whether they terminate on common busses.
You do not run an additional grounding electrode conductor from the subpanel to the water pipe - that's done at the service equipment.
Whether you run a 60 or 100 amp panel depends on what you think you'll do with the shop in the future. It partly comes down to cost. The 100 amp breaker will cost a bit more than the 60 amp breaker. The conductors will definitely cost more to run a 100 amp subpanel but you may feel it's worth it to give yourself that capacity now.
60 amps requires 4-4-4-6 NM (copper), 6/6/6/8 THHN/THWN (copper) in conduit or 4-4-4-6 SER (aluminum).
100 amps requires either 3-3-3-4 THHN/THWN (copper) in conduit or 1-1-1-3 SER (aluminum).
If you run individual conductors (THHN/THWN), it must be in conduit. If you run NM-C or SER, it does not need to be in conduit.Rob

[Tim Dorcas]

I've done a few things since I asked the question. One, I bought a couple of books that describe the process in detail. Honestly it's doesn't look that bad. The other thing I've done is price out parts. It will cost about $400 in parts to put in the subpanel and receptacles versus $1200 to have an electrician do it. Keep in mind that I'm running this to my garage which is attached to the house and it's almost a straight shot from the main panel to the section in the garage I want to put the panel.

So I'm going to continue to read and make I feel completely comfortable but my overall impression is what everyone is telling me, it's not too bad.

[Rob Russell]

Tim,

Is your garage attached to your house or is it freestanding?

Rob

[Cliff Rohrabacher]

It is really, Really easy.

[Robert MacKinnon]

I'm also wiring my shop (attached garage) with a small 60A subbpanel. The circuit capacity is currently fixed at 40A because I am using an existing house circuit currently terminating in a 40A breaker. The main panel is 125A and is 2/3 loaded. I can punch through the wall at the dryer socket to the interior of the garage and install the subpanel at that point.

All my machines are 240V. My machine complement is (1) 2HP tablesaw, (1) 2HP bandsaw, (1) 0.5HP dust collector, (1) 1HP drill press and (1) 4HP RPC for a planer/thicknesser. There is an existing house circuit for lights and convenience outlets so 120V off the sub panel is not envisioned. I am a single-person shop so I will never (in the forseeable future) run more than one machine and the dust collector symultaneously.

My plan is to run two circuits. One 20A for the RPC terminating in a NEMA 14-30R receptical and another 20A terminating in two NEMA 6-20R recepticals for all other machines and the dust collector. Is this a reasonable plan or am I missing something? Thanks.

[Norman Hitt]

[QUOTE=Alan DuBoff]I don't get this. Tim stated that he has 6 slots available. He didn't state how much amps total on the breakers in the panel already. With 6 slots, and especially if the panel is in the garage, what is the advantage of running a seperate panel, it will go to the same 125A panel he has. Since he has 6 slots, he can do quite a bit in that panel.

Alan, I don't believe his main Breaker panel is in his garage, and that is why I recommended the subpanel. He stated that he whould be able to run the cable without having to dig anything up or destroy any walls, and that the run out to the garage would only be about 25 feet.

[Russ Filtz]

Russ,

What size subpanel did you run and what did you use for conduit?

Rob

I only had something like 100 or 125A service, and i added a 60A sub. The sub panel itself can be pretty much any size (whatever you can get cheap!), just size your breaker according to your needs AND what your load calcs say. (yes I had to do the NEC load calcs to get a permit, showing you aren't over loading the main panel). Also, I used a "main lugs" panel where the subpanel breaker was installed in my main panel. The power feeds just get screwed down to extensions of the breaker busses. That's how you can custom size your 100A rated panel down to 60A or whatever. I think the other style comes with a main breaker already installed? You'd have to scrap it to down size if you need/want to and waste money.

For conduit, I used plain old EMT, the thinnest stuff. My local codes required all circuits to be in conduit anyway. Plus I like the extra safety. With conduit, I pulled separate conductors (individual wires), not a "cable". Code may even require this, not sure. Better for heat dissipation.

If you use conduit, try to use bends where you can for direction changes. Fittings just add more potential snag points, plus you need to have a support/anchor at every coupling (not a big deal, just more hassle). Bending tools can get expensive, but my orange box let me bring in my own conduit and use their bender for free!

[Rob Russell]

Russ,

I'm guessing you pulled #6 THHN/THWN conductors.

FYI, the conduit is not for heat dissipation, it's to protect the individual conductors. Conduit actually reduces the ampacity of conductors because it slows down heat dissipation. As an example, the #6 THHN/THWN you would have needed for your 60 amp subpanel could have been run through #8 if the conductors were in "free air" with an ambient temp of 86F/30C. (That's disregarding any rules about how the conductors may be installed in a house, just looking at the current carrying capabilities of the conductors.) #6 THHN/THWN has an ampacity of 95 amps (based on 75 degree-rated connections) in free air vs. 65 amps in raceway (conduit), cable or buried.

On installing conduit, pull points are required every 360 degrees of bend - more frequent pull points makes it easier!

Rob

[Tim Dorcas]

Tim,

Is your garage attached to your house or is it freestanding?

Rob

It is attached.

[Rob Russell]

It is attached.

That makes your job easier. If the garage had freestanding, you likely would have needed to drive ground rods and attach the EGC to those ground rods.

Because your garage is attached to the house, this is a non-issue.

[Jerry Bittner]

Your local/state building code applies of course but normally a conduit is not necessary if the wire is enclosed in dry wall or otherwise isolated. For example, I ran my 100 amp subpanel from the main located in the garage to the my shop which is an extension of the garage. We ran the wire inside the wall from the main up over and onto the floor of the garage ceiling and it lays exposed on the ceiling joists until it comes down through the wall in the shop. And to be on the safe side, I used a 100 amp breaker in the main to service the subpanel.

Incidentally, got my subpaner from HD and they did have a 100 amp, 20 circuit at a decent price.

[Rob Russell]

Your local/state building code applies of course but normally a conduit is not necessary if the wire is enclosed in dry wall or otherwise isolated.

Good point. In the Chicago area, for example, NM-C (aka "Romex") is not allowed. Basically, all wiring there has to be in conduit - even normal branch circuits.


For example, I ran my 100 amp subpanel from the main located in the garage to the my shop which is an extension of the garage. We ran the wire inside the wall from the main up over and onto the floor of the garge ceiling and it lays exposed on the ceiling joists until it comes down through the wall in the shop.

If any of that conductor is near an opening from the garage into the attic space, the wiring needs to be protected. I don't have my code book right here, but that's something to be careful about. Even "laying" on top of the joists, there are rules about running the cable and you want to make sure you follow those.

[Russ Filtz]

Russ,

I'm guessing you pulled #6 THHN/THWN conductors.

FYI, the conduit is not for heat dissipation, it's to protect the individual conductors. Conduit actually reduces the ampacity of conductors because it slows down heat dissipation.
Rob

Pretty sure it was at least #6, been about 5-6 years since i did it. Moved since then, so I can't check! I had an electrical engineer at work that was an ex-contractor that helped me. Passed all inspections no problem!

On the conduit issue, what I meant to say was that it's bad to use an insulated multi-conductor "cable" inside of conduit due to trapping even more heat. With conduit, at least in my area, you HAD to use individual conductors.

I still feel better with full conduits throughout the house. I don't trust romex or BX running through walls, even with nailer plates. Hear of too many people nailing through wires!