Q: In the MV to HPS conversions, did they install new heads with HPS gear & lamps or did they open up existing heads and replaced both ballast & lamps? If both procedures were done, what would be the ratio of NEW heads to Refurbished? Many aluminum posts in my city are over 40yrs old from the mercury days.

On my old resdidential street back in 1994, I distinctly remember a worker going from one light to the next with a bucket-truck to convert silverliner OV15 heads containing 250watt MV lamps to HPS. He took half an hour per light and more. Looks like these silverliner OV15's are still in service with 100w HPS, most likely since 22 years ago (just a NEMA 10 sticker on most of them).

When I take close-up pics of other HPS heads now, I often see the make/model/watts/date sticker sometimes along with a NEMA tag, but mostly it's either or. The manufacture date I come across is invariably from 1980 to 1995. Those near 1980 are for sure HPS original heads.

I would guess that back then they had the time and human resources to change ballasts. I always imagined they didn't take the time to do it pole top, however. I always thought they would have replaced a few fixtures with new HPS ones, take the old ones to the street light repair shop, replace the ballasts and test them, and then return to swap more, and so on until all the work is done. However, since you mention they took half an hour at each light, it might suggest otherwise unless the crew was working really slowly...

I've been trying to remember exatly what I saw back in 1994. One person with a bucket truck worked well into the night. It's possible that he opened the mercury head, disconnected the incoming wires, removed the head, replacing it with an HPS one. I distinctly remember a few of HPS heads suddenly lighting up in the dark. All that work must've taken him half an hour each.

In my area (NEPA) it was a full swap to new, no retrofits. Since we still had a very large percentage of incandescent in service also, we at PP&L opted for full conversion to HPS, both from mercury and incandescent. The only mercs left in service were the private area lights. There are still many in service, and the rare failures get 70 or 100w HPS open bottom buckets. Happily, here in Scranton PA, no indication of LED in the future yet....

"Mercury to HPS" retrofit bulbs (specially made to be used with mercury ballasts) were often screwed in, in replacement of existing or burned-out mercury bulbs, without changing the ballast. Sometimes you can recognize the progressive retrofit when the same street mixes mercury and HPS bulbs, in a random order on the same old fixtures.

We never considered the retrofits here in PA. The bulbs didn't have the same lifespan, were sometimes fussy, and were always 2 to 3x the cost per lamp. 

In my area in the mid 1980s all the fixtures were replaced, mostly with AE 13s, Cooper OVSs, and GE M250s on the streets and GE M400s on the freeways.

We never considered the retrofits here in PA. The bulbs didn't have the same lifespan, were sometimes fussy, and were always 2 to 3x the cost per lamp. 

I agree that these bulbs are far from the ideal solution!

I went through my photo archives and found 2 slides of the same street light. Clearly the head was converted to an OVZ from Westy OV14B. (Thanks for the id fellas). No refurbishing was done on site then. See uploads..

http://www.lighting-gallery.net/gallery/displayimage.php?pos=-121704
http://www.lighting-gallery.net/gallery/displayimage.php?pos=-121705

Then we have conversion lamps to convert HPS to metal Halide!

Over here we did both, some old MV fixtures got replaced with new HPS fixtures during the changeover in the 90s while some got new ballasts, lamps and even HPS NEMA tags. New installs of MV stopped around the late 70s. Some of the retrofitted fixtures survived until everything was changed out to LED two years ago.

Here in upstate NY, they replaced the heads. I was getting all kinds of stuff, and had access to several hundred OV-20's, but didn't know what the heck these were back then and left them. There was a pile of street lights at the scrap yard over 20 feet high and 100 feet around! In those dys I took them for yard lights, didn't collect them and even clearended /C and /W and stuff like EH-1 lamps were lamps I would just use, as I never considered them vintage. Fast forward 20+ years and it is all different, and I wish I had gotten much more! Later! Rick "C-6" D!

I've been trying to remember exatly what I saw back in 1994. One person with a bucket truck worked well into the night. It's possible that he opened the mercury head, disconnected the incoming wires, removed the head, replacing it with an HPS one. I distinctly remember a few of HPS heads suddenly lighting up in the dark. All that work must've taken him half an hour each.

Thats quite interesting, we lost all our MV where I am in the late 70s, early 80s, but there was 2 guys in a bucket truck, and they never did any of the work at night!
Back then, our MV lanterns, (unlike the US ones), were with the gear mounted remote at the base of the column.

The guy at the top would replace the lantern, (from 80watt MV to 35watt LPS), whils the guy at the bottom would take out the existing MV ballast, and time clock, and fit the new PC unit.
We also didn`t get HPS lamps here until well into the 2000s!!

In Northern/Central California, Pacific Gas & Electric (PG&E) reballasted thousands of mercury vapor heads to HPS back in the early 80s, besides replacing lots of others with new HPS heads. However all of these are now under fire because PG&E is changing out all its street lights to LED.