Rooftop mast for MH parking lot luminaire

[lordofpi]

I've done lots of outdoor light installs, but for some reason never like this. I'm about to re-do a job I had done in the past where the business owner wanted a 400 W metal halide wallpack installed right next to one of their main entrance/exit doors for employees. I mounted the fixture within 18" of the door frame, secured to a block wall, and everyone was happy. Now I get a callback saying that since summer has hit, insects congregate about the fixture (obviously) and fly in the building in mass swarms whenever someone enters or exits.

Business owner now wants the same light, same location, but extended about 24" above the roof line (1-story building) to draw insects elsewhere. I purchased the yoke-mount version of the same fixture, the Hubbell MHSY400H8. I figured I can mount this on an RMC mast of some sort; the supply house also sold me a bracket for doing so, but I cannot quite see how this is to be done. It almost looks like I would have to mast this with 2" RMC based on the width of the bracket, and then I would have to run LFMC inside of it, or something similar. Am I overcomplicating this? Pictures are below; please let me know if I can provide some more info to help describe this:

 

[mdshunk]

You're exactly right. Bolt that adaptor to the fixture yoke, and slide the adaptor over your bullhorn or mast. Run your cable inside the bullhorn, out of that hole in the adaptor, and whip over to the knockout in the flood.

 

[mdshunk]

I wonder why they didn't just sell you a slipfitter fixture in the first place? I'm pretty sure that same fixture is available in a slipfitter version.

 

[lordofpi]

I was secretly hoping there was a way for me to use the RMC as a complete raceway in which to run conductors. In addition, I wanted for there to be a way to use 1" or so instead of having to use 2", especially since I must offset around eaves and gutter, but I guess that is not possible. Guess I'll have to rent a bender.

Three more questions: (1) does the RMC have to be tied-in to a box down below, or does it merely sit there as a means of sheathing LFMC, which will be connected to a box. (2) Will LFMC have to have an independent means of support on a vertical run sheathed in conduit such as this? (3) Will I have to support the mast with guy wire?

Also, the supply house I went to was not one of my favorites, and they never have exactly what you want, don't feel like ordering it, etc. I wanted to start this job this afternoon, so I didn't want try to be picky and get stuck waiting.

 

[220/221]

Just a thought......if you used a square tubing riser it will mount more securely to the building (flat on flat) and you can mount the yoke directly to it.


Offsets? Nevermind

It would be more beneficial to see pics of the building. What you are describing sounds like a mess.

Move it laterally, farther from the door?

Set a pole?

 

[mdshunk]

I don't know about all this RMC idea you have. Slipfitters are normally mounted on a proper pole, bracket, or bullhorn. Something like one of these is what I picture myself using for your job:

http://www.elights.com/brackets.html

There's a million and one varieties of these brackets. GE has tons of different ones.

 

[quogueelectric]

I was secretly hoping there was a way for me to use the RMC as a complete raceway in which to run conductors. In addition, I wanted for there to be a way to use 1" or so instead of having to use 2", especially since I must offset around eaves and gutter, but I guess that is not possible. Guess I'll have to rent a bender.

Three more questions: (1) does the RMC have to be tied-in to a box down below, or does it merely sit there as a means of sheathing LFMC, which will be connected to a box. (2) Will LFMC have to have an independent means of support on a vertical run sheathed in conduit such as this? (3) Will I have to support the mast with guy wire?

Also, the supply house I went to was not one of my favorites, and they never have exactly what you want, don't feel like ordering it, etc. I wanted to start this job this afternoon, so I didn't want try to be picky and get stuck waiting.

You could run 1" and adapt up to 2" at the top with an adaptor and short nipple if you wanted to. Or a t or c condulet enough to make a splice and switch to carflex or sow up to the fixture.

 

[lordofpi]

I'll ride out and shoot a pic of the building tonight, but essentially what I was going to do was make a service mast, I guess, and mount the light to that. Here is a little diagram (best I could do with MS Paint):

 

[lordofpi]

You could run 1" and adapt up to 2" at the top with an adaptor and short nipple if you wanted to. Or a t or c condulet enough to make a splice and switch to carflex or sow up to the fixture.

I was thinking that was possible too. The fixture is probably around 35-40 lbs., so I want to make sure it is secure, but 2" GRMC just seems overboard. Straps to keep conduit in place, but I still need a support against vertical force, i.e. gravity too, I would think.

Incidentally, I thumbed through the very very brief instructions, and it actually calls for SOW, so I might get off easy in that respect.

 

[quogueelectric]

I was thinking that was possible too. The fixture is probably around 35-40 lbs., so I want to make sure it is secure, but 2" GRMC just seems overboard. Straps to keep conduit in place, but I still need a support against vertical force, i.e. gravity too, I would think.

Incidentally, I thumbed through the very very brief instructions, and it actually calls for SOW, so I might get off easy in that respect.

It might look better with 2" straight up through the soffit and penetrate the roof have the owner put a pitch pocket in the roof for you and have his roofer install the pitch pocket so you dont have roof leaking liability. If you need to pull it closer to the front you could spin a 90* on at the top to bring it closer to the front with no shadows. I think the straight pipe would look better. Another option is back to back 90*s to bring it in front of the soffit.

 

[lordofpi]

Back-to-back 90s to keep it even with the soffit will probably be easier than getting the owner to get a roofing contractor involved. My main point of concern then is how to support the pipe.

 

[mdshunk]

Back-to-back 90s to keep it even with the soffit will probably be easier than getting the owner to get a roofing contractor involved. My main point of concern then is how to support the pipe.

I sure wouldn't guy back 2" RMC with a little biddy light on it. Heck, you don't even need to guy back 2" service masts that only stick up that far normally.

 

[lordofpi]

I sure wouldn't guy back 2" RMC with a little biddy light on it. Heck, you don't even need to guy back 2" service masts that only stick up that far normally.

Do you think that a couple of 2-hole straps along the way would suffice, then? As I said in an earlier post, I don't intend to bring the RMC all the way down to the junction box, or the ground for that matter, since I will really be running in LFMC sleeved in the RMC. I know a few straps ought to suffice, but I want to be sure there is no play in this. Would it violate code for me to put a weld where the straps meet the pipe since it is only a sleeve rather than a complete raceway?

 

[LarryFine]

I would suggest forget about running the mast all the way to the present fixture location. It wold look terrible, in my opinion. Instead, I'd look at mounting the head direccly to the building, maybe with one of the mounts like on the page Marc linked to.

Then, run LFMC or whatever is appropriate to the original location if that's where you must feed from, using a blank plate and a 90? connector if there's a box. Nobody says you have to use the hole in the pipe adapter even if you decide to use it.

 

[LarryFine]

By the way, is it possible to abandon the present feed and re-supply the light from the roof somewhere? That would certainly neaten up the outcome.

 

[220/221]

I'lll wait for the picture of the building but they way you have drawn it will look like hell IMO.

If it's a flat roof you might want to build a rack and just mount it up on top.

If the overhang is as drawn you could just penetrate the eve/roof and go straight up with the pole.

You can also sink the pole about 30"' deep in concrete, away from the building.

 

[lordofpi]

Larry, that may be an option. I really wanted to get some height out of it though, and I don't know if one those mounts to which Marc linked will achieve that. The other option would be to secure one of them directly to the roof, which I really don't like at all. In addition, there is no efficient way to pull power from the roof, though that would certainly help.

Below are the pictures of the building. The main roof is flat, but in this particular spot (this was an addition), it rises about 4 inches for a 10 foot rafter run -- essentially flat. There are no eaves or gutters anywhere on the original part of the building; the flat roof uses scuppers to drain instead. In this one part where _I_ am working, however, there naturally is a gutter (probably 6 inches in diameter) to block me. I originally thought there were eaves too, but I'm not seeing any now that I look more closely. I _guess_ I could cut the gutter if necessary and have it re-done.

 

[lordofpi]

Also, for your enjoyment, the other side of the building (certainly not my work); I'm sure this is up to code :roll: . By the way, yes, most of that is Romex, not UF.

 

[mdshunk]

I'd mount that light down at the corner of the building, above the orange traffic cone. Use one of those wall brackets I linked to.

 

[lordofpi]

I'd mount that light down at the corner of the building, above the orange traffic cone. Use one of those wall brackets I linked to.

Well, that really is a last resort. Based on the beam angles, where it is in the middle of the wall is perfect because it covers the right half of that wall too, which is quite a bit out in the lot from where I was shooting.