MH Ballast selection

[Slick Fork]

Hi there,

I recently found my 250 watt HQI ballast was pulling 420 watts for normal operation and I think I've decided to replace them with Electronic Ballasts.

I was hoping for some guidance as to which produce the best par ratings, have the best reliability, etc. I have seen Sanjay's site, unfortunately he doesn't rate some of the more commonly available ballasts like the galaxy's, lumatec's, vertex's, coralvue's, etc.

Also, how tough are these to wire? Will I have to rip apart my Giesemann fixture or will I be ok to just splice wires?

Thank You

 

[Mister Scopas]

I think that you are dealing with two separate issues.

First, if you have a genuine 250 HQI ballast, its probably an ANSI M80 spec ballast. A properly functioning M80 ballast will only dissipate 290 watts of input power. If your M80 ballast is "pulling" 420 watts then it its drawing about 150% of the current that its supposed to draw, and something is wrong. The device is malfunctioning and needs to be removed from service before it starts a fire.

An M80 ballast is supposed to be fused with an 8 amp slow-blow fuse, so that when the ballast fails the fuse will isolate the ballast from the line voltage so that you don't burn down your house. Unfortunately, most reefers don't think about these things and fail to install inline fuses.

Right now your ballast is pulling 150% more current than it should, though its not pulling the 250% to 300% that would be required to blow the fuse. This suggests that either your power consumption measurement is inaccurate, or you've identified a subtle problem that can only get worse with the passage of time. Better to nip it in the bud now than to let it go. My personal recommendation would be to have someone who is qualified check out the ballast for you.

 

[Slick Fork]

The ballast came with the fixture, it's a giesemann eco 230. I'm in agreement that it should be replaced, just trying to figure out with what and how to!

 

[Mister Scopas]

Second, I think that most people have a misconception about how to source the proper ballast for their lamps.

IMO choosing the ballast before you choose the lamp amounts to putting the cart before the horse. You might be better off by choosing the lamp that you want to use first, and then selecting a ballast that properly (optimally) operates the lamp.

I know that I should duck as I say this because electronic ballasts are all the rage right now, but IME electronic ballasts NEVER produce the highest PAR values. This is because they are power regulating devices. Regardless of what type of input they see, they will regulate the amount of power delivered to the lamp so that the power dissipation remains constant at the ballast's specified value.

Magnetic ballasts typically provide higher total power because they are current regulating devices, not power regulating devices. The electric company plays a subtle trick on you by increasing your line voltage from 120 VAC to 125 VAC or so to account for voltage drops in the distribution network. A side effect of this is that you will consume more power, as wattage increases in proportion to voltage as current remains constant. By increasing your line voltage from 120 to 125 VAC your meter will run 4% faster and you'll pay for 4% more power as you use the same amount of current. This results in higher power dissipation by the magnetic ballast, which in turn drives the bulb a bit harder, resulting in higher PAR.

IME a magnetic ballast that is properly matched to its lamp will always outperform an electronic ballast for this reason.

 

[Mister Scopas]

Geissman. Hmm. I wasn't thinking about that as I wrote my first post. ANSI M80 is an American ballast spec. I don't know the specs on the imported fixtures, so my post could be in accurate. Sorry.

 

[PaulErik]

How did you measure the input wattage? The ballast should not be drawing 420 watts.

Giesemann fixtures equipped with a magnetic ballast usually have the lamp ignitor housed inside the light fixture. The ignitor must be bypassed/removed if you use an electronic ballast.

 

[Slick Fork]

I used a hardware store type watt meter to measure the input voltage. The igniter in the fixture would probably explain the fourth and fifth wires on the connector at the ballast.

I know that e-ballasts produce less par, part of what I need to decide is whether or not the drop in Par is 1) still going to provide enough light for the corals (all my sps are in the top 8" of the tank with no plans to put light hungry critters below that, and 2) if the drop is acceptable considering the considerable gain in electricity savings

 

[PaulErik]

Does the meter give you a wattage reading or did you measure voltage and current to get the wattage. The best meter for an end user to use is a Kill-A Watt meter. It appears the wattage posted does not include the power factor. The power factor will be approximately .80 plus or minus a few percent on that ballast. You must use a meter (like a Kill-A-Watt) that will calculate the power factor to get the true wattage of the ballast. If the 420 wattage reading does not include the power factor then the wattage is really approximately 336 watts with a .80 power factor. That seems correct for your ballast.

 

[Slick Fork]

The meter gave me a wattage reading, it also gave me amps and volts (which I can't remember right now)

So, the power meter is wrong when it tells me it's drawing 420 watts? I don't understand this power factor.

 

[PaulErik]

Some meters do not include the power factor. To get the correct wattage draw from inductive loads you must use one that includes the power factor (like the Kill-A-Watt meter). To calculate the wattage for inductive loads you do: volts x amps x power factor = watts. The ballast you have cannot draw 420-watts unless it is not a 250-watt ballast.