I'm not sure about other manufacturers, but I believe there was a period where GE used the same core and coil assembly in their 700w and 1000w mercury cobraheads. They just used a different sized capacitor for the different wattages. H35 700w and H36 1000w mercury lamps run at the same 265v arc voltage. The H35 700w runs at 2.8-3.0A lamp current and the H36 1000w at 4.0-4.3A so it was a matter of using a lower capacitance capacitor to lower lamp current. This works in the common CWA ballast design used for these sized lamps where the capacitor value directly affects the lamp current.

Another word of note, the North American H35 700w mercury lamps are not compatible with the European ones, I believe the European ones run at a lower arc voltage and high current. Same thign goes for the H34 1000w and the H36 mercury lamp, the H36 is rated at 265v, 4.0-4.3A and the H34 at 135v, 8.0-8.1A.

Of interest, from the same documentation where I pulled those numbers from, the H36 1000w mercury lamp is also rated at 1500w operation, you get a impressive 85000 initial lumens but lifespan decreases to just a mere 2000 hours. The 1000w mercury lamps are rated at 63000 lumens, 24000 hours.

 

Gavita makes a 750W DE HPS light for plant growers.Those have electronic ballasts that run the lamp 100Khz 400V @ 1.875A 1000W Gavita HPS same frequency and voltage but 2.4A.Those suckers are BRIGHT-BRIGHT!!!!!Intersting on that mercury ballast-provide two cap values and a switch to switch between them-that way you could run 700W or 1000W bulbs!That would be nice!

Another word of note, the North American H35 700w mercury lamps are not compatible with the European ones

... which, it seems, were comparatively rare, at least in (East) Germany. It was a surprise to some people that this rating exists at all.

Of interest, from the same documentation where I pulled those numbers from, the H36 1000w mercury lamp is also rated at 1500w operation, you get a impressive 85000 initial lumens but lifespan decreases to just a mere 2000 hours.

Same story for the 2000 watts Narva. It was widely considered as overambitious attempt, going beyond the limits of this lamp technology, and obsolete once MH lamps were available. Installations with these lamps have quickly been replaced, and so the production of these monster mercs ceased already in 1981/1982.

Majority of the 700W mercury vapor ballasts are 1,000W ballasts with smaller capacitors. Duke uses these duel wattage 250/400W PSMH street lights & the only thing that separates them from each other is a jumper that parallels the capacitor inside the street lamp.

Majority of the 700W mercury vapor ballasts are 1,000W ballasts with smaller capacitors. Duke uses these duel wattage 250/400W PSMH street lights & the only thing that separates them from each other is a jumper that parallels the capacitor inside the street lamp.

Dual watt PSMH ballasts? I had no idea those existed.

Running any lamp on a ballast not designed for it runs the risk of under- or over-running the lamp and/or ballast, with life-limiting issues for both.

You can run 700W mercury bulbs as long as the capacitors are correct. For example taking a ballast out of a X1 M-1000 & replacing the small capacitor with a 2.5 ufd & replacing the two large capacitors with something adding up to 15 ufd. Typically the X1 ballasts used 3.0-3.5 for the small capacitor & 30-34 for the big capacitors.

Here is an important note:

When using lower wattage HID lamps on an HX or a reactor/choke ballast, lowering the capacitor values will NOT affect the lamp’s operation. If you want to use lower wattage HID lamps on HX or reactor/choke ballasts, you would need to adjust the output impedance. You can adjust impedance by adding additional reactor/choke ballasts in series with the lamp or by adding incandescent lamps and/or resistors in series with the lamp.

Lowering the capacitor values for running lower wattage HID lamps only works with CWI and CWA ballasts.

If you try to add impedance to a CWA or CWI ballast, the lamp will run at a higher current.

Interesting with the capacitor set up in the US?, here in the UK, the most common circuit for 700 watt mercs are a 250 watt and 400 watt MV ballast wired in parallel