We noticed a big difference to how our Goldeye ran after installing the correct rating of capacitor to bring the PF up to .85 from .4 (ish) 
Before it was running really hot and needed additional cooling, but not after the work had been done. 

I'd never trust one of those el-cheapo adaptors, no matter what the rating of the lamp.!

It won't make any difference to your bill, but it will make a difference to the power used. The lamp will draw more current and if you're on the brink of the maximum capacity of the wiring, it could push you over.

Personally I always like to make sure the PF of my discharge lamp circuits is as high as possible. Here, that's usually done with a capacitor across the supply, it's often different on your side of the water.

Not usually. If you are a normal customer, they are billing you for real power in kWh which accounts for power factor in the equation of voltage times current to get the *real power*.
But if you are an industrial customer, you can be being billed for apparent power in kVArh (which doesn’t account for power factor and just straight up multiplies the voltage by the current), then you will be charged more for a low power factor.

But chances are you’re not because apparent power is only Really charged to industrial customers, and not residential customers.

According to the records I can find, the clear band design was introduced towards the end of 1976 for all powder-coated BT lamps irrespective of whatever the coating material was. This was an emergency quality project and by start of 1977 it should have been applied to all types.  Even though it was strictly only needed for certain quartz lamps it was applied to all, because it was the same coating machines that produced all lamp types.

In 1979 the phosphor adhesion problems were solved and full coating was resumed.  Since that was not an emergency project it seems to have taken longer to introduce, and it was not until 1980 that all types had been converted.  The BT56 line seems to have been the last to revert to full coating.  If anyone has the time, it could be interesting to make a study of all the Sylvania coated HID lamps on this site from the period eg 1975-1985 to identify which coating design was in use!

I did a conversion on a Holophane Bantam 2000 to 39w CMH at one point. I made a small bracket to adapt the existing medium base lampholder mounting holes to a G12 lampholder. As for the height, I made it so it roughly matched the arc tube on the 175w MH it was originally designed for.

Note that there also exist E26 to G21 screw in adapters. However the plastic on mine wasn't suitable for the heat of a 150w CMH lamp

I am looking to convert an AEL series 315 to run 150w G12 base CMH lamps with an electronic ballast. It should be pretty easy to mount the ballast on the power pad and rewire everything, but how should I go about making a CDM-T lamp compatible with the existing (FCO) optical assembly? Should I make a bracket that extends the lampholder out or maybe at an angle?

Any help will be appreciated.

I have been running a 175 watt MV Westinghouse RMA dusk to dawn for a couple years. It has a 120 volt NPF HX ballast. What I was wondering is this. Does the inefficiency of the NPF ballast severely affect the electric bill? Like versus a CWA running on 240 volt or a HPF HX ballast? And also I have wondered, versus a HX, how lossy is a single coil reactor ballast? And yes of course a reactor would be running at 240 volts, and I have been led to beleive that operation at 240v makes any light cheaper to run.

In my area a lot of the older lights from the mid 70s onwards were factory HPS, before the advent of LED there was stuff like Unidors, OV-15s, and B2255s which were factory HPS. There were some older lights such as Unistyles and M-400s, those were more likely to be factory MV here.

The oldest HPS install here was from 1967, it used GE M-400As.

Exactly what I was thinking guys . Plus , a lot of older fixtures had long enough production runs to have been made in multiple lamp types (Silverliners , M-400A , M-1000) As for NEMA tags , even they can be replaced so as mentioned above , unless one physically sees the original label inside , there's really no way to tell unless the fixture in question pre-dates MH or HPS such as a clamshell .