MH to HPS Conversions.

[joe_347V]

Seems quite rare as most places convert from HPS to MH/CMH or LED but how common are these conversions in your area?

I only know of one place that did this, a local community centre used to have MH parking lot lights when it opened in 2005 but they were converted to HPS in 2011. Pretty odd I have to say though.

They also swapped the MH gym lights to fluorescent highbays and the MH pool lights got self ballasted corkscrews. (Also had fluorescent vapourtight added highbays between the old fixtures, some of the ballasts have failed though)

[Mike]

nope it hasn't happened here. the stop and shops here with HPS galleria squares have been converted to PSMH by drilling an external ballast box on top of the show box which looks odd to say the least yet interesting. it looks like a highbay ballast housing but maybe a little smaller and with no mounting hook or anything obviously. then the cable comes out the side of the ballast box and into the side of the fixture like a Boston Retrofit lol

[joe_347V]

Seems odd how they converted them but I guess that's the lazy way. I wonder if the original ballasts are still inside.

I'm guessing they replaced the ballasts in the MH shoeboxes as there's no tacky box mounted on top. Still a odd conversion as most places want to move away from HPS.

[Mike]

oh actually the resort i stay at in NH in the summer has a few shoe boxes that were spot reballasted with HPS. They were all originally PSMH but i think two are HPS now. It was probably all the electrician had on the truck... plus most PSMH replacement ballasts are only multi-tap so they take up more room than the OEM one and HPS ballasts are cheaper. but converting all of them is definetly weird.

[joe_347V]

Yeah, my best guess was they converted from 320w or 400w MH to 250w HPS to save energy. Personally I prefer using 250w CMH instead though.   

I wonder if the resort is still HPS, if I was the owner I'd get them changed back to PSMH just so the lights are consistent. 

[Lumalux]

This is a little off-topic, but I know of two recent instances where parking garages originally outfitted with MH fixtures were converted over to fluorescent.  In one case, they replaced the MH fixtures with 4 foot fluorescent fixtures; in the other they simply disconnected the MH ballast and installed self-ballasted helical CFLs directly into the MH fixtures.  Building management previously had replaced the MH bulbs with LED retrofits (which provided good light but many began to fail within one year), so they began replacement with CFLs.  The light from the CFLs is very good and mimics that of a DX mercury vapor.

The problem with using MH in installations like parking garages (where they burn continuously) is that they never get turned off periodically as advised. I forget why this is required but it has to do with the capsule cooling. If left to burn continuously, they are prone to explode.

[lights*plus]

The problem with using MH in installations like parking garages (where they burn continuously) is that they never get turned off periodically as advised. I forget why this is required but it has to do with the capsule cooling. If left to burn continuously, they are prone to explode.

Simple failure is more likely. At any rate, converting away from M-H is a cost costing measure from having to relamp often and the uneven appearance of M-H before or after relamping.

I've noticed that cheaper M-H lamps, those without "scandia" incorporated in the arc-tube (used to prevent depletion of scandium) become markedly dimmed after a burn-in period. The more expensive M-H lamps, with scandia in the composition of arc-tubes, remain bright and evenly white.