wiring in my pole barn

[alan camby]

I am running conduit down the center of the barn to supply power to lights.
Every 8 foot I am installing a junction box and coming out of both sides with MC cable that will feed ceramic keyless lamp holders.

I am running all 12 awg THHN off of one breaker to feed these 10 lights. I am ending the run going down to a 4" square box on the wall that will have the light circuit. I am running a second circuit off of a second breaker that will feed power to a outlet in the last 4" box. So this 4" box will contain the switch (20amp HD) and a 20 amp outlet.

Do I need to run 2 grounds or can one 12 awg wire protect both circuits in this conduit run. It seems kind of silly to have to land 2 grounds in the last box.

 

[alan camby]

Next question.

I will be adding more runs out of my new breaker box to feed other circuits.
I currently bought one spool each of green, black and white THHN in 12 AWG, 500ft spools.
I need to have one 30 amp 220 outlet so was going to pick up a 100 ft spool of 10AWG in red and black.

Do I need to get a spool of 10awg green for the ground? Or can I use the 12 awg green wire?

Years ago romex was sold with a little dinky ground wire and now it has a full size matching ground. So does the ground have to match in my 30 amp circuit?

Thanks

 

[alan camby]

The above questions are for my 27x76 pole barn with an additional 12x60 foot room on the back. main part of the barn is cut in half with a wall. So I am around 27x 38 in each room. The lighting circuit in post# 1 is for just one room. I will be running conduit into the other room to feed it with another 20 amp lighting circuit.

I am using 42 watt CFL 6500K bulbs from Feit electric. The are equivalent to 200 watt incandescent. I have tested 3 of them and they seem good for my barn needs. The barn is a storage building and is not going to be my main shop area. I think the 20 amp breakers should be good for 10 in each room. That puts me at 420 Watt. Even with the poor power factor of CFL's I think I have more then enough current available before hitting 1920 Watts (80%)of continuous current from a 20 amp breaker.

 

[2ManyProjects]

I am running conduit down the center of the barn to supply power to lights.

Next question.

I will be adding more runs out of my new breaker box to feed other circuits.

The above questions are for my 27x76 pole barn with an additional 12x60 foot room on the back.

Whoa, Nellie!

Three posts in less than 20 minutes, and you're all over the map.

The FIRST thing we need to address is some of your assumptions about those CFLs...

I am using 42 watt CFL 6500K bulbs from Feit electric. The are equivalent to 200 watt incandescent.

I presume you mean these:

http://www.homedepot.com/p/Feit-Ele...CFL-Light-Bulb-12-Pack-ESL40TN-D-12/100661903

I have tested 3 of them and they seem good for my barn needs.

Well, in the sense that they would likely be superior to conventional incandescent lamps of similar output, sure. But that's not really the yardstick you should be using. Look at the basic specs for these bulbs:

Light Output (lumens)   	2800
Wattage (watts)   		42
Average Life (hours)   		8000
Price:  			$98.96 / 12-pack
    				$ 8.25 each

Now compare that to, for example:

http://www.1000bulbs.com/product/90168/USH-3000102.html

Lumens (Initial):  		3050
Wattage (watts)   		32
Life (hours)   			30,000
Price:  			$55.56 / 25-pack
    				$ 2.22 each

Obviously, the tubes produce more light, for MUCH less cost (particularly by the time you figure that you will be replacing dead CFLs nearly four times as often as the tubes will need replacement). But MUCH more importantly, at ~95 lumens/watt the tubes are FAR less expensive to operate than the CFLs (which produce less than 67 lumens/watt). So for equivalent brightness with the CFLs, your electric bill will be about 42% higher -- FOREVER.

You REALLY need to re-think this.

The barn is a storage building and is not going to be my main shop area. I think the 20 amp breakers should be good for 10 in each room. That puts me at 420 Watt.

Your math is off, at least if you mean that one breaker should supply power to both rooms. Two rooms, ten bulbs per room, each bulb consuming 42 watts, yields a total of 840 watts.

That said, a single 20A circuit would still be adequate, looking at it solely from a load standpoint. But again, that's not quite the way you ought to be looking at it. Regardless of the load calculations, you should split up your lighting (in each room) between at least two separate circuits/breakers. That way, if/when one trips (or must be shut down for maintenance), you won't be left completely in the dark.

Now, regarding some of your other points...

I am running all 12 awg THHN off of one breaker to feed these 10 lights. I am ending the run going down to a 4" square box on the wall that will have the light circuit. I am running a second circuit off of a second breaker that will feed power to a outlet in the last 4" box. So this 4" box will contain the switch (20amp HD) and a 20 amp outlet.

What size conduit are you planning to run? I'm not intimately familiar with the official limits of fill ratios, derating for multiple conductors, etc.; but as a very broad statement, "bigger is better" in terms of being able to EASILY make the pulls.

Do I need to run 2 grounds or can one 12 awg wire protect both circuits in this conduit run. It seems kind of silly to have to land 2 grounds in the last box.

If you are using properly fitted EMT, the conduit itself can serve as the ground. That's not to say you SHOULD do that, but it's acceptable. Given that, I can't imagine that a single ground wire within the EMT (which itself isn't "required" in the first place) could be ruled "inadequate".

HOWEVER... Just to be clear: When I say "ground" here, I am speaking ONLY of the "Equipment Grounding Conductor" (EGC). Each circuit still requires a dedicated and segregated Neutral (a.k.a. "Grounded Conductor").

The above questions are for my 27x76 pole barn with an additional 12x60 foot room on the back. main part of the barn is cut in half with a wall. So I am around 27x 38 in each room. The lighting circuit in post# 1 is for just one room. I will be running conduit into the other room to feed it with another 20 amp lighting circuit.

Keep the two breakers; but as noted above, arrange the loads differently. Put (about) half of each room's lighting load on "Breaker A", and the other half on "Breaker B".

 

[alan camby]

Both rooms will have 10 bulbs with the option of adding more if needed. Each room will have its own 20 amp circuit, so the total will be around 420 watts per breaker/room.

Using 1/2" emt which has a fill capacity of nine 12 gage wires.

Yes I understand the difference between ground and neutral.

Already tested the bulbs and I am happy with the output. I can always add more down the road if needed. Your prices do not include fixtures. My fixtures are around $1.50 each.

Anyone know the answers to the two questions.

Thanks

 

[Mustang51js]

You only need one ground if you decide to run one for the 20 amp circuits, but you need the #10 ground if you decided to run one for the 30 amp line.

 

[alan camby]

You only need one ground if you decide to run one for the 20 amp circuits, but you need the #10 ground if you decided to run one for the 30 amp line.

Thanks, that is what I wanted.

I am also under the assumption , from looking around the net, that metal conduit is not a acceptable ground. Is this correct?

 

[Mustang51js]

It is acceptable but some say no because your relying on the connectors to complete your ground. If you have the wire it wouldn't hurt to run it but I wouldn't go out of the way to buy it, but that's just me.

 

[alan camby]

It is acceptable but some say no because your relying on the connectors to complete your ground. If you have the wire it wouldn't hurt to run it but I wouldn't go out of the way to buy it, but that's just me.

Now you got me really confused. you said that I needed 10 gauge ground for the 30amp circuit. Then in this post you said to not run the wire if you don't have it.

 

[Mustang51js]

I was saying if you decided to run a ground then you would need the #10. In reality you don't need to run a ground at all with the pipe.

 

[2ManyProjects]

Both rooms will have 10 bulbs with the option of adding more if needed. Each room will have its own 20 amp circuit, so the total will be around 420 watts per breaker/room.

Which will leave each room totally dark if/when that one breaker trips or needs to be thrown for any reason. So like I said, you want to split the lighting load in any one room between two circuits/breakers. Those circuits/breakers do NOT necessarily need to be dedicated to one room; so two breakers will still handle the whole thing. (And BTW, they do NOT need to be 20A types; standard 15A breakers and AWG 14 wiring will be more than adequate for even twice that much load. If you want to run AWG 12 and use 20A breakers "just because", it won't hurt anything; but it's a waste of money.)

Already tested the bulbs and I am happy with the output. I can always add more down the road if needed.

It doesn't matter how many you use; for any given amount of light production, the CFLs will ALWAYS cost more to buy, require more frequent replacement, and cost more to use. Adding more of them just puts you further in the hole, faster.

Your prices do not include fixtures. My fixtures are around $1.50 each.

Oh, Jeeze... We've got another one that can't see past the initial purchase price.

Saddling yourself with CFLs so as to be able to insanely cheap-out on the fixture is the epitome of a false economy. You "save" money on the fixtures once; the higher operating costs go on FOREVER.

Anyone know the answers to the two questions.

You were given those answers already.

I am also under the assumption , from looking around the net, that metal conduit is not a acceptable ground. Is this correct?

No, that "assumption" is NOT correct. As previously explained, the EMT itself can be used for the EGC. Whether or not it is "Best Practice" to do so is a matter of some controversy; but it remains perfectly "acceptable" per the NEC.

 

[Charles (in GA)]

The barn is a storage building and is not going to be my main shop area.

I think this sums up the OP's use of the building well. Infrequent use of lighting and probably no detail work being done. The CFL's will probably last years and years in this type of use, and since cost does matter to most people, they are probably the best choice unless something better happens to fall in the OP's lap for free.

Charles

 

[alan camby]

If effiecincy was the goal I should be looking at T5s or LEDs. T8 are old technology when talking efficiency.
Go into any new big box store and they will be using T5's, some times with the combination of skylight that shut off lighting on bright days.

It all boils down to how much you use a building. This building is for storage. It might see 1 hour of use per week. This does not warrant the latest and greatest technology. Would you put T8's in your attic, or crawl space?
I hope you don't see the inside of my home. I just converted all of the incandescents over to cfl,s.
I think the house would look silly with tubes.

You are right though, If I was building a shop, where hours are spent per day, I would be looking at T8 or T5. I would not be surprised if T8 goes away in the near future, then my fixtures would be NG. T5 is slowly taking over. I helped convert a building over from T12 to T8 about 10 years ago. Today that would be a bad choice for a 170,000 sf manufacturing facility.