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Roadkill Score: NGrid 10ft Truss arm
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Found this on the side of a freeway. A car had hit the pole and the arm fell off the pole. The reason the arm fell is because the weld joining the arm to the mounting bracket failed. So I will need to find a way to make new brackets for it and weld them in place where the originals were. This was on an aluminum pole so it had metal pole brackets but since I'll be starting from scratch, I will design wood pole brackets for this so I can attach this guy to a wood pole.
This arm is quite impressive. The wall thickness of the pipe used to make this is 3/16" thick and the diameter of the top pipe is 2" at the luminaire end (it's oval shaped at the pole end; about 3" wide and 2" tall) and the bottom pipe is 1-1/4" diameter. There's some minor dings and scratches but other than that this thing is in great shape.
Attached to this was the remnants of a 250W HPS GE M-250R2. The top housing broke into two pieces, leaving the reflector and capacitor on one piece and the ballast, ignitor, and terminal block on the other piece. The housing broke at the PC socket so the PC socket was loosely hanging by the wires on the portion still attached to the arm. The PC was a 2011 Fisher Pierce, missing the cover and circuitboard totally smashed. The refractor door was also nearby without a scratch on it. No glass anywhere though. The 250W HPS Sylvania lamp also survived intact. The fixture dates to 2012. I actually remember when the fixture and pole were installed to replace a knockdown.
This is the location of the pole. As you can seen, back in 2011 there was no pole there at all. Not sure how long it's been laying on the side of the freeway but it was after October...
I saved the door, reflector, lamp, slipfitter & bolts, terminal block, and screws from the fixture. I also set aside the ballast, capacitor, and ignitor to test those at a later date. The ballast has a broken spade terminal but other than that was not impacted. Ignitor and capacitor look fine too. Won't know for sure til I test though. The reflector was a little banged up but I beat the dents out. PC socket has a chunk missing but overall could still be reused. As long as a PC is installed in it, the missing chunk won't be a problem. the door doesn't have a scratch on it though. Amazing! My guess is that the door fell off right at impact and the arm probably took awhile to fall. First the top weld had to fail. Then the arm probably hung by the bottom weld for a short while before it let go and the arm and fixture dropped to the ground. The highway crew probably tossed the arm and parts against the fence away from traffic since it's property of the electric company, not the state DOT.
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Andy: nope not yet. I'ts winter so I have to wait until we get some nicer weather. The day of this pic it was in the lower 60s and the very next day we got a foot of snow! We just got 2-3" more last night. Won't be getting out to the shed for awhile! That's why I stashed all my lighting goodies building up in the basement in the shed on that nice warm sunny day. My basement is basically a "waiting room" for new lights where they "hang out" after they've been cleaned before being moved to the shed.
I like the idea of a slip-on bracket too but I want it to look as authentic as possible. But I'm no good with welding and lack the tools to make the mounting plate brackets so this might be a project I hold off on.
The drawing for the tapered elliptical arm is also online.
I don't have a need for one now but if I ever do, I might make a detailed CAD of a 6' truss arm from the drawing and then send it off to a shop so I can have my own repro MTO truss arm.
For the wood pole style, I'd want to create brackets like you see here for an authentic look. Seems pretty basic to make with the right tools. Granted I don't possess the right tools lol. Just get the flatbar, cut it to shape, bend the curve of it to fit against the round pole, drill the holes, and weld it to the arm.
The MTO website has a lot more lighting drawings too, there's one on NEMA tag style and placement, sign lighting, sign lighting details, a table of fuse ratings for mercury lamps, and a very detailed drawing of a overhead sign truss. You can pretty much replicate all of the MTO's designs lol.
Also, some older 1950s tapered arms in the Blackstone Valley Electric area (which originally held crescent moon lights from what I understand) use a triangle and look like this here. I love those really old 1950s tapered arms. They have a smoother bend at the top and the triangular plate looks cool. I don't believe NEES (NECo & MECo) used those older style tapered arms. If they did, it was in very small numbers.
Wow MTO has a spec sheet for everything! lol. Interestingly, their NEMA tag specs are nothing like they are actually. HPS uses yellow, MH uses just red (not fluorescent red) and they're not reflective at all.
Yeah I like how the MTO basically has plans for everything freely online. Yeah the NEMA tag one is puzzling, the MTO as far as I know just use whatever tag the fixture manufacturer puts on the light. I haven't seen any like what the plan describes. Would be kinda neat to have a few MTO official NEMA tags made though.