Hey guys I am kind of baffled, down at the highway I happened to be there the other evening as the cobra heads struck on for the night time.  There was an accident so I was sitting in traffic for over 20 minutes and got to see full warm up.  Basically every color of my HPS wall pack but backwards! LoL it started the color of HPS and ended with a bluish mercury, passing deep red in the middle.  Is this some form of metal halide? Very interesting!  I will try to get pictures!

Thanks ahead of time!

-Mike

What was the final color of the lamp, when it reached full output?
1. Regular new HPS lamp, start out 1. pinkish white or white (Depending of the age) -> 2. orange LPS, -> 3. golden HPS color (Sometimes very new HPS lamps may exhibit sodium color upon starting, before going to step 1).
2. Regular old redded out HPS lamp, starts out 1. white -> 2. bluish mercury for a min -> 3. pinkish white -> 4. orange -> reddish or pinkish orange (Somtime very old lamp may skip step 1, and would start dirctly in bluish color).
3. New penning start HPS lamps, starts out 1. red neon color -> 2. white -> 3. orange LPS -> golden HPS color (Sometimes step 2 replaced by a bluish color for several second and then pinksih white before going to step 3).
4. Old redded out penning start HPS lamp, starts out 1. red neon color -> 2. bluish mercury colour for a min -> 3. pinkish white -> 4. orange  -> 5. redded or pinkish orange.

Some newer HPS lamps are designed to go blue close to EOL. Some in my area exhibit a whitish blueish light, similar to coated or clear mercury vapour, and after a few days (or weeks) start cycling, and then need to be relamped. I believe this is part of some kind of anti-cycling feature, or to make eol lamps noticeable (to ease maintenance) or both.

The ones that are intentionally blue at EOL, are the non-cycling unsaturated vapour HPS lamps.
In the regular ones, that cycling at EOL and get redded out, the blue light during run-up or after hot restrike, isn't intentionally.
Unsaturated vapour HPS lamps, don't suffers from voltage rise during life, as the sodium loss, like the regular ones. Thats is the reason why when all of the sodium lost, they exhibits a bluish mercury color, and don't cycling at all.
Regular HPS lamps, usually cycling, when reaching to this state.

Thanks guys!  The final result of all 3 were what I would expect from a clear mercury vapor, a whiteish blue so I wonder of they were all EOL.  I would have to say they weren't all that bright either.  I didn't get to see the wattage number underneath though.

Could they perhaps have been metal halide retrofit lamps designed to run on standard HPS gear ?

If he is in 240v-lland then the standard Pulse Start MH is used on HPS gear

I don't think that all types of pulse start MH lamps, are suitable for HPS gear.
The old Tungsram and Osram non universal long arctube MH lamps, were designed only for MV gear and a HV ignitor.
The old Philips HPI-T (Without "Plus" or "Master"), were also suitable only for MV gear and a parallel 750V ignitor.

The standard MHs today are. Look at all Eltams HPS ballasts - they are all rated for HPS and MH (when used with superimposed ignitor)