Running power to an external building

[beelzerob]

We're building an external structure (basically a pavillion) for storage, and I'm going to run power to it so there's lighting. I had some leftover 2" conduit, so I figured I'd use that.

I asked an electrician about my plan overall. I'm just going to tap into an existing garage outlet and run that power through the conduit (probably 30 - 40 ft) to the external building to light it. He said that was fine, but he'd use 12 ga instead of the standard 14 ga. Now, I've got plenty of 14 ga on hand, so I'd rather use that. I do have some uncertain amount of 12 ga too laying around. Does it really make any difference? And if so, would it help at all if I used as much of the 12 ga as I have, and then used 14 for the rest, or would it not make any difference if I mix and match them?

While I was at it, I figured that pavillion was the perfect place for an eventual weather station. So I figured I could just run some cat5 through the 2" conduit when needed, since there will be plenty of room in there. Is that a bad plan? I'm guessing that violates some kind of code or practice, having them in the same 2" conduit, huh?

thanks for any input. It helps to post these things, as invariably someone brings up something I didn't think about.

 

[dutchyn]

While I was at it, I figured that pavillion was the perfect place for an eventual weather station. So I figured I could just run some cat5 through the 2" conduit when needed, since there will be plenty of room in there. Is that a bad plan? I'm guessing that violates some kind of code or practice, having them in the same 2" conduit, huh?

It is definitely against code here in Canada. The CEC says that low-voltage (class 2, less than 30V) circuits can only share the same box, conduit, or raceway with a high-voltage (class 1, more than 30V) circuit if and only if the class 2 circuit controls the class 1 circuit; and all conductors are insulated against the maximum voltage of all conductors in that box, conduit, or raceway; and the class 2 circuit is kept 25.4 mm from the class 1 circuit. The notice to installers that came with the EDT iLine lighting says essentially the same thing, and except the distance was 1/4", if I recall correctly.

 

[mdesmarais]

Does it really make any difference? And if so, would it help at all if I used as much of the 12 ga as I have, and then used 14 for the rest, or would it not make any difference if I mix and match them?

12 ga will have lower resistance, so you won't lose as much. Not much of an issue if all you are going to do is put in a couple of light bulbs, but a little more problematic if you put in an outlet or two that might get used for power tools or something with high draw.

Typically you can only join wires in a box- not in the middle of a conduit run.

 

[SnyperBob]

14 gauge is usually good for a 15 amp circuit. 12 gauge is good for 20 amp. Copper, is cheap, if I were you I would probably run the 12 gauge.

 

[SnyperBob]

When I did mine, I ran the electrical thru metal conduit and the low voltage thru PVC conduit. So they don't run in the same pipe.

 

[beelzerob]

Well, it's definitely for lighting...maybe 4 bulbs, if not more (the roofed area is 24' by 32'), and I had thought to put an outlet out there for...whatever. I could see taking the circular saw out there to cut a piece of wood as needed.

And I definitely wouldn't put a connection within the conduit. Those would be in boxes outside somewhere else.

Seems the concensus is to NOT run any low voltage in the same conduit. I guess I'll go buy some cheaper, smaller conduit to run alongside it in case I ever do want to run something out there. Probably much more likely is that my weather station will use wireless, so that the eventual lightning strike won't directly fry my HA stuff (instead, it will fry it indirectly via the power I'm putting out there).

 

[BraveSirRobbin]

I'm just going to tap into an existing garage outlet and run that power through the conduit (probably 30 - 40 ft) to the external building to light it.

Are you sure that the existing garage outlet is powered via a 15 amp breaker? Check that first. If it's a 20 amp (most are at my house, but it varies) then you HAVE to run 12 gauge.

 

[DavidL]

Don't forget a GFI if outdoors.

 

[beelzerob]

I'm just going to tap into an existing garage outlet and run that power through the conduit (probably 30 - 40 ft) to the external building to light it.

Are you sure that the existing garage outlet is powered via a 15 amp breaker? Check that first. If it's a 20 amp (most are at my house, but it varies) then you HAVE to run 12 gauge.

Part of the discovery process will be finding out which breaker controls the outlet I want to run from. I did have them wire in some 20 amp outlets in the garage, but to my knowledge there are only 3 of those, and this isn't one of them.

I'm planning on running it from an existing GFCI outdoor outlet on the garage wall. The conduit will also come in that same garage wall, so all I have to do is connect to that outlet, run the wire up into the storage area, across the trusses, and then down where the conduit comes in. Pretty easy route.

If there is already a GFCI outlet in the loop, then does the outlet I put in the pavillion also have to be GFCI, or will that one outlet breaker do it for all of them?

 

[BraveSirRobbin]

If there is already a GFCI outlet in the loop, then does the outlet I put in the pavillion also have to be GFCI, or will that one outlet breaker do it for all of them?

Beelzerob, I'm not a professional electrician, but it is my understanding that you want only ONE GFCI on a single breaker run. This GFCI should be mounted at the first access (outlet/switch) point. There may be other code restrictions and hopefully one of our members knowledgeable with this type of code compliance can chime in.

Make sure you read the directions and head the wiring guidelines of the GFCI as you have to get it right or else your downstream outlets will not be protected.

THIS How-To describes installing an X-10 outdoor outlet, but there is also some GFCI info (with pics) there you might want to browse through.

Also, invest in an outlet (three light) tester WITH a specific GFCI test button and test to make sure the GFCI will "pop" when that test button is pressed at ALL your exterior outlets (cheap insurance that everything is wired correctly).

You may have mentioned this, but will any of this conduit be run undergound (more code compliance info if it is)?

 

[beelzerob]

Yes, from the house to the pavillion, the conduit will be buried about 2 ft down.

Fortunately, the voltage sensor I bought a while ago came with a GFCI tester (which I never figured I'd use).

 

[sda]

Now, I've got plenty of 14 ga on hand, so I'd rather use that. I do have some uncertain amount of 12 ga too laying around. Does it really make any difference? And if so, would it help at all if I used as much of the 12 ga as I have, and then used 14 for the rest, or would it not make any difference if I mix and match them?

What type of wire/cable do you have? You can't use NM (i.e. romex) underground (even in conduit). You have to use individual THWN wires in conduit or UF cable.

You also need a disconnect at the structure. A snap switch will do.

 

[beelzerob]

Well, that's why I posted! I forgot about that...I was just going to run my romex.

Whatsa snapswitch?

 

[sda]

Well, that's why I posted! I forgot about that...I was just going to run my romex.

easily overlooked detail.

Whatsa snapswitch?

plain old toggle switch that you use to turn on lights.
you can get a weatherproof switch box kit at the big box.
if you're running 20a circuit, you'll need to swap the standard 15a switch in the kit to a 20a.

 

[beelzerob]

Oh...so basically, as long as I have my lights turn on or off via a light switch out at the pavillion, then that's considered a "disconnect"? Not a problem, that's what I was gonna do.

I was actually kinda torn on whether to go with a light switch out there, or motion based lights, or even a light switch at the house so I could turn it on before going out there. I'm thinking overall probably just having the lights on a switch out at the structure is the best way.