4 15a circuits or 2 20a circuits?

[Weslsew]

My two car garage was built with only one outlet, so I'm planning to run emt around the perimeter and add plenty of outlets. I'm thinking 10-15 boxes with double outlets in each. I figure If I'm gonna add outlets, I'm gonna add enough. Ideally I would love to run 4 20a circuits so that each box has outlets on separate circuits, with 20a gfcis and 20a outlets, but after figuring that up its way over my budget so I have to cut back.

The wire is the main cost, and I'm figuring it's roughly the same price to run only two 20a circuits or four 15a circuits, with either using 15a gfcis and 99 cent 15a outlets.

Im leaning toward doing the two 20a circuits. What would you do?

 

[mm08822]

What are you planning to do in there? How much simultaneous loads will be present?

If you just don't want to walk to plug something in and little loads, 2 20a ckts is plenty. And you dont need 20a recepts.

 

[James-W]

I am a bit confused. Is this an attached garage, or is it detached? Are you running power from the house breaker panel to the garage, or just tapping into the one outlet you already have?

If you are running power from the house electrical panel to the garage, I would suggest you put a sub-panel in the garage and then run the power to the outlets from the sub-panel.

 

[Stuart in MN]

First, let us know what state or country you're in as code requirements can vary.

Assuming you're in the US, it's allowed to have 15 amp receptacles on a 20 amp circuit as long as there are more than two receptacles, and a standard duplex receptacle counts as two. So, the only real cost difference whether you use 14 awg wire (for 15 amp circuits) or 12 awg wire (for 20 amp circuits.)

 

[Weslsew]

What are you planning to do in there? How much simultaneous loads will be present?

If you just don't want to walk to plug something in and little loads, 2 20a ckts is plenty. And you dont need 20a recepts.

Sorry, should have included this. Just what I would call typical garage stuff... Running saws, grinders, chargers for various batteries. Maybe add a small fridge one day. Probably won't be much simultaneously.

I am a bit confused. Is this an attached garage, or is it detached? Are you running power from the house breaker panel to the garage, or just tapping into the one outlet you already have?

If you are running power from the house electrical panel to the garage, I would suggest you put a sub-panel in the garage and then run the power to the outlets from the sub-panel.

This is an attached garage and the house panel is in the garage so it's very easy to add circuits.

First, let us know what state or country you're in as code requirements can vary.

Assuming you're in the US, it's allowed to have 15 amp receptacles on a 20 amp circuit as long as there are more than two receptacles, and a standard duplex receptacle counts as two. So, the only real cost difference whether you use 14 awg wire (for 15 amp circuits) or 12 awg wire (for 20 amp circuits.)

Florida. That's correct with the wire being the main cost. The place I'm looking sells in 50', 100' or 500' spools so that's why it's about the same price for 500' of 14 as it is for 150' of 12.

 

[mm08822]

Sorry, i assumed it was an attached garage but didnt confirm. Sounds like 2 ckts is still probably ok. Worst case, its conduit. Add/split ckts later if needed. I'd run 12's.

 

[Firebrick43]

I bought 6 rolls of wire the other day. (3) of 500' of 14ga thhn solid and (3) of 12ga thhn solid 500'. It was at Menards (which you don't have) and was 29$ for 14 and 41$ for 12. So 12$ difference. Times two for white and black and the difference is 24$ between 4 15 amp and 4 20 circuits. I checked Miami Florida Home Depot and prices were within a dollar.

Don't "have to" have ground with emt as it is the ground. Have to pig tail ground screw on receptacle to box ground point.

 

[justsam]

Don't forget you need a GFCI at the head end of each circuit, and use the LOAD side to feed other receptacles downstream. You could use GFCI breakers, but it will be more money.

 

[mike_s]

Run 12ga for all outlets. You might want heavy saws or compressors later and 12 gauge is always better on 120v motors

 

[Stuart in MN]

Florida. That's correct with the wire being the main cost. The place I'm looking sells in 50', 100' or 500' spools so that's why it's about the same price for 500' of 14 as it is for 150' of 12.

Certainly #12 is going to be more expensive, but I'm surprised you're finding that big of a difference in cost; I deal in design of commercial structures so I'm not very familiar with what the retail market is like. It may be worth shopping around some more to see if you can get a better deal on the #12, I think the only reason they are charging that much more is because they can.

 

[sberry]

You don't nee all that, 2 or 3 circuits is plenty and maybe 1 somewhere for heavy saws if that's the case. 10-15 outlets with doubles, this is 60 fargin outlets, what is it you expect to do? Put recepts on 12, 14 is for lights.

 

[75gmck25]

If cable cost is your big concern, another option is to use two runs of nm 12/3 and wire it as multi-wire branch circuits (two double breakers, four circuits), breaking it out to the four GFCI's at the first receptacle on each circuit. I'd have to price the cable to determine if the savings would be noticeable, but usually 12/3 is fairly reasonable.

I have also found that NM cable prices at HD do not seem to make sense when you look at what is on the shelves. Sometimes you can get 100% more cable for only about 50% more cost when you buy longer lengths. Lowes is the same, where 100 feet of 12/2 is $44 and 250 feet of 12/2 is $61.

Its challenging to compare cable prices on the web sites because you can't easily filter on conductor size and length and get a good list of products. I usually have to visit the store and compare directly.

Bruce

 

[cj7jeep81]

If cable cost is your big concern, another option is to use two runs of nm 12/3 and wire it as multi-wire branch circuits (two double breakers, four circuits), breaking it out to the four GFCI's at the first receptacle on each circuit. I'd have to price the cable to determine if the savings would be noticeable, but usually 12/3 is fairly reasonable.

I have also found that NM cable prices at HD do not seem to make sense when you look at what is on the shelves. Sometimes you can get 100% more cable for only about 50% more cost when you buy longer lengths. Lowes is the same, where 100 feet of 12/2 is $44 and 250 feet of 12/2 is $61.

Its challenging to compare cable prices on the web sites because you can't easily filter on conductor size and length and get a good list of products. I usually have to visit the store and compare directly.

Bruce

He's wanting to run in conduit, so NM wouldn't work out. Plus, prices on 12/3 are insane. I wanted to do exactly as you recommended in my shop, but 12/3 was almost double the cost of 12/2. Supply and demand I guess.

And I agree with sberry. 40-60 outlets in an attached 2 car garage seems a little excessive to me.

 

[wyliesdiesels]

You don't nee all that, 2 or 3 circuits is plenty and maybe 1 somewhere for heavy saws if that's the case. 10-15 outlets with doubles, this is 60 fargin outlets, what is it you expect to do? Put recepts on 12, 14 is for lights.

15 duplex recepticles would be 30 outlets not 60.

U mustve hit x2 on the calculator.

Still, an insane amount for a small garage.

He's wanting to run in conduit, so NM wouldn't work out. Plus, prices on 12/3 are insane. I wanted to do exactly as you recommended in my shop, but 12/3 was almost double the cost of 12/2. Supply and demand I guess.

And I agree with sberry. 40-60 outlets in an attached 2 car garage seems a little excessive to me.

Nothing prohibiting NM-b in conduit just not wise and a waste of money.

 

[Weslsew]

Thank you all for the replies. It's not really that many outlets: one box on each side of the garage door for using stuff out in the driveway, three over my work beach, two on the front wall and three on the other side wall. It's not much more to use double boxes with two duplex receptacles than a single box with one duplex. This way I can ensure I'll always have plenty of outlets.

I think I'm going to run 12ga. I'm still shopping around but it looks like about $32 for 150' or $47 for 500' at Home Depot. Might as well buy the 500 and that may be enough to do more than two circuits. We'll see. I know the emt can be used as a ground but I just feel safer running a ground wire.

 

[tyme2par4]

15 duplex recepticles would be 30 outlets not 60.

U mustve hit x2 on the calculator.

Still, an insane amount for a small garage.

From my understanding of the OP, he want's 10-15 boxes, with 2 duplex outlets in each box. That would indeed be 60 outlets.
"Double outlets" could be deciphered either way though.

 

[CJ7VFR]

.....I think I'm going to run 12ga. I'm still shopping around but it looks like about $32 for 150' or $47 for 500' at Home Depot. Might as well buy the 500 and that may be enough to do more than two circuits. We'll see. I know the emt can be used as a ground but I just feel safer running a ground wire.

Go with the largest amount of wire, in feet, that you can afford to get now. As you found out already, the difference between the 150 foot roll and the 500 foot roll of 12 gauge wire is only about 15 bucks more for over three times the wire!

The nice thing about having the extra wire is that once you get your receptacles where you think you want them, and you start to use them, you can always see if you require an outlet in a different spot. Then you either add more, or move the ones you have, using the wire you have left over, so they would be in better and easier to use locations.

Jim

 

[ard]

You need to shop in a different place...

Cost difference 12 vs 14 should not be THREE fold! (500ft=150f)

Last time I bought #12 stranded I think it was $43 a roll of 500ft.

Also, you want 20A circuits. All the 15 amps circuits in the world will do you no good if one saw draws 16 amps....

 

[James-W]

If it were me, I wouldn't even consider 15a outlets, especially in a garage where you will be using power tools.

 

[wyliesdiesels]

Thank you all for the replies. It's not really that many outlets: one box on each side of the garage door for using stuff out in the driveway, three over my work beach, two on the front wall and three on the other side wall. It's not much more to use double boxes with two duplex receptacles than a single box with one duplex. This way I can ensure I'll always have plenty of outlets.

I think I'm going to run 12ga. I'm still shopping around but it looks like about $32 for 150' or $47 for 500' at Home Depot. Might as well buy the 500 and that may be enough to do more than two circuits. We'll see. I know the emt can be used as a ground but I just feel safer running a ground wire.

not sure which home depot youre shopping at but all the Home Depots around here dont sell THHN on 150' spools. They only sell 50' 100' and 500' spools.

I dont even see 150' spools listed on their site.

500' spool here is $56...

From my understanding of the OP, he want's 10-15 boxes, with 2 duplex outlets in each box. That would indeed be 60 outlets.
"Double outlets" could be deciphered either way though.

oh ok i missed the quad box comment.

You need to shop in a different place...

Cost difference 12 vs 14 should not be THREE fold! (500ft=150f)

Last time I bought #12 stranded I think it was $43 a roll of 500ft.

Also, you want 20A circuits. All the 15 amps circuits in the world will do you no good if one saw draws 16 amps....

Who said it ws3 fold? Difference is only $15

If it were me, I wouldn't even consider 15a outlets, especially in a garage where you will be using power tools.

name a tool that has a 20a plug.

20a outlets are unnecessary. U can use 15 receptacles on 20a circuits as long as there is at 2 outlets on the circuit and a duplex counts as 2 outlets.

 

[ard]

..it's about the same price for 500' of 14 as it is for 150' of 12.

Who said it ws3 fold? Difference is only $15

OP did?

 

[James-W]

Name a tool that has a 20a plug.

20a outlets are unnecessary. U can use 15 receptacles on 20a circuits as long as there is at 2 outlets on the circuit and a duplex counts as 2 outlets.

Why is that important? If I plug in a tool that uses 9 amps and a buddy plugs in a tool in the same outlet that uses 8 amps, what happens then? I was under the impression it is the total amperage from the outlet that counted.

Also, I sometimes plug in a heavy duty extension cord with 3 outlets on it. I run the extension cord outside and then we may be using more than one tool at a time on the extension cord. In my opinion it is better to have the 20 amp outlets even if you don't need them on a regular basis.

 

[wyliesdiesels]

Why is that important? If I plug in a tool that uses 9 amps and a buddy plugs in a tool in the same outlet that uses 8 amps, what happens then? I was under the impression it is the total amperage from the outlet that counted.

Also, I sometimes plug in a heavy duty extension cord with 3 outlets on it. I run the extension cord outside and then we may be using more than one tool at a time on the extension cord. In my opinion it is better to have the 20 amp outlets even if you don't need them on a regular basis.

What u dont know is that there is absolutely NOTHING different about the internals on 15a and 20a outlets. The only difference is the faceplate.

And 15a outlets are rated for 20a pass through.

THAT is why it matters.

And thats why code allows 15a outlets on 20a circuits.

So, do u have any tools with 20a plugs?

If the answer is no then youre wasting money on outlets u dont need.

 

[James-W]

What u dont know is that there is absolutely NOTHING different about the internals on 15a and 20a outlets. The only difference is the faceplate.

And 15a outlets are rated for 20a pass through.

THAT is why it matters.

And thats why code allows 15a outlets on 20a circuits.

So, do u have any tools with 20a plugs?
If the answer is no then youre wasting money on outlets u dont need.

I have no idea. I am not at home and won't be home for several more days so I can't go check and see. I am at friend's house who just had hip surgery a week or so ago. I am helping him out until he gets back on his feet and can drive again.

If both outlets are the same then why (other than money) does it matter if someone uses the 20amp instead of 15amp?

 

[sberry]

The reason to use a 20 is to allow the use of a 20 tool. It says that the installer intends that to be ok. It doesn't mean it even needs to be an actual 20 tool.
Here is an example. A school , maybe a lab with several things on a general, some experiments etc, say 10A load, all is well then the cleaning lady comes along with a 13A floor tool, trips the breaker by using the wrong outlet, hooks this high draw tool on a computer circuit, off goes the breaker, got to reset it all.
Put it on its own or one other damage isn't done, limited to the circuit I'd should be. Now,,, you do not have true 20 equipment. I have a hundred pieces, not a single one with 20 end. In my career used a couple pieces, a special paint sprayer cost 5 grand and a concrete floor grinding machine, stuff most people do not have. Even new wire welders come 15 end as do common chop saws.

 

[bobabuee]

my take on this:
1.buy 3/500ft spools cheaper in long run 12 gauge.
2.buy 15 amp reciprocals.
3.buy few 20 amps put were you might have hi draw amp tools.
4.put as many reciprocals as you like. this means need for less extension cords on the
floor to trip on.
5.run 2/ 20 amp separate circuits for welder etc. on separate sides of garage.

6.run 2 circuits of reciprocals on each side of garage beginning with gfi reciprocal

7.if adding work bench add 3 circuit if spanning both opposing walls.

Do all it once the way you want,its cheap if you do it your self. (if you have the skills
to do it right)

expensive if you have it done.

 

[James-W]

The reason to use a 20 is to allow the use of a 20 tool. It says that the installer intends that to be ok. It doesn't mean it even needs to be an actual 20 tool.
Here is an example. A school , maybe a lab with several things on a general, some experiments etc, say 10A load, all is well then the cleaning lady comes along with a 13A floor tool, trips the breaker by using the wrong outlet, hooks this high draw tool on a computer circuit, off goes the breaker, got to reset it all.
Put it on its own or one other damage isn't done, limited to the circuit I'd should be. Now,,, you do not have true 20 equipment. I have a hundred pieces, not a single one with 20 end. In my career used a couple pieces, a special paint sprayer cost 5 grand and a concrete floor grinding machine, stuff most people do not have. Even new wire welders come 15 end as do common chop saws.

I had thought 15 amp outlets were for 15 amp circuits and 20 amp outlets were for 20 amp circuits. Apparently I was wrong, apparently you can use 15amp outlets on 20 amp circuits. Once again I learned something here.

I don't know if I have 20 amp tools or not, I am not at home right now, but I know that I do have an older model pizza oven with a very heavy duty plug on it and I have a really old heater for melting roofing tar (a buddy of mine has it at the moment) with a heavy duty cord and plug.

 

[sberry]

Its always possible to find something 20A, a pizza oven may qualify. They would absolutely want to prevent it from running on a shared circuit. Making a 20A available simply says,,, its ok to plug 20 here, making it . 15 simply says circuit not intended for support of a 20, says its a general and may have other stuff on it, doesn't even mean you cant pass 20 thru a 15 plug exactly but most pieces come with 15 ends are designed with certain parameters in mind.

 

[jarhead]

I have no dog in this fight...

But I would recommend buying extra wire, it will save you money in the long run. Someday you will kick yourself in the *** if you don't.

My *** is still sore...