Yep. The M-250A I'm getting when I visit him is from Holbrook too. It's 100W MV and has a 240V ballast. I'll be converting it to 175W MH/MV, since I settled on converting my OV-25 to mogul base Incandescent.
Oddly though the brown photocells are 120V so possibly this had/has a 120V photocell and a 240V ballast. The NEES (New England Electric System) which included basically all of what NGrid now controls, had always used 120-277V PCs up until the HPS changout. 99% of the mercs installed in the NEES area had simple 240V ballasts while the HPS fixtures installed during the changeout and today are all 120V (some of the utility owned freeway lights in RI are an exception). In the 60s the NEES decided to custom order their PCs (mainly from Fisher Pierce and Ripley) in light gray to match the new era of gray colored streetlights, so there's a reason why one would think a 240V light in the NEES area is 120V. I hope the weather is good for this saturday so i can get lots of pics.