My Monthly Stupid Question - Metal Halide

[George Stolz]

Does a 70W MH ballast have to supply a 70W MH lamp? What happens if you were to use a 60W or an 80W MH lamp?

 

[480sparky]

My monthly stupid reply: Where do you get 60 and 80W MH lamps?

If you were to locate either, I think it would light, but possibly at the expense by the shortened life of some component. I'm just shooting from the hip, though.

 

[hurk27]

Does a 70W MH ballast have to supply a 70W MH lamp?

Yes and No, depends upon the ballast, many are now multi watage, I have seen magnetic for 50/70w, and electronic go from 35 to 100 watt

What happens if you were to use a 60W or an 80W MH lamp?

never seen a 60 or a 80 watt, but the example is the same, in a case where the lamp was higher then the ballast rating, the lamp wont last for very long, in the case where the lamp is lower then the ballast, ballast won't last.

But the reality is I have seen it done and I have seen them last in both cases, but I wouldn't do it as it is just not right for me to do.

 

[George Stolz]

Yeah, I was just mostly throwing that out there as a frinstance.

I encountered a bunch of dead ballasts with 50W lamps and 70W ballasts, and my supply guy was incredulous as though I should known that from day one. I advised the customer to go through and check the lamps before it started tattooing more ballasts, but somewhere deep down I was wondering if the supply guy was absolutely right or not.

 

[hurk27]

Yeah, I was just mostly throwing that out there as a frinstance.

I encountered a bunch of dead ballasts with 50W lamps and 70W ballasts, and my supply guy was incredulous as though I should known that from day one. I advised the customer to go through and check the lamps before it started tattooing more ballasts, but somewhere deep down I was wondering if the supply guy was absolutely right or not.

run into this allot, especially around apartment complexes.

Also keep a look out for pules start lamps in regular MH non-PS fixtures as this is also a no no.

 

[iMuse97]

Monthly???

Monthly???

My teenaged son implies that I ask stupid questions daily! :grin: Of course, I know what he does not, that in about six years I will be much smarter than I am now.

 

[iMuse97]

Monthly???

Monthly???

Stupid computer tried to send the same message twice.

 

[Cow]

Does a 70W MH ballast have to supply a 70W MH lamp? What happens if you were to use a 60W or an 80W MH lamp?

My thinking is, if a 70w ballast was made to drive a 60-80 watt lamp, it'd say so right on the ballast. Don't you think?

I always tell customers to follow the fixture label exactly when replacing lamps. Doesn't always stop them from trying other types though...

 

[quogueelectric]

The ballast kind of dictates what the fixture will or will not do. The fixture wiring and lamp size are kind of mechanical in nature. It is what it is.

 

[hardworkingstiff]

I encountered a bunch of dead ballasts with 50W lamps and 70W ballasts, and my supply guy was incredulous as though I should known that from day one.

Were these fixtures he provided for a new job that you installed? If so, he has a point. If you ordered some 15-amp 1-pole breakers and the supply house sent you 20s, would you install them anyway? He probably feels this should have been caught by someone paying attention. He sent them wrong in the 1st place, so it's his problem (if he wants future business), but I do understand his point of view.

Were the lamps packed with the fixture or sent in a separate box? If they came packed inside the fixture, then he should shut up.

 

[goldstar]

As long as we're asking stupid questions and giving stupid answers I'm going to make a stupid assumption:roll:. I would think that a ballast that is rated for a specific wattage bulb (say 70 watts) would be able to handle the illumination of any wattage bulb up to the wattage that is being demanded (say 50-70 watts). The wattage of the bulb determines how much power is required to drive it. By the same token, if a higher wattage bulb were installed (say 80-100 watts), the wattage capability of the ballast would not be enough to illuminate the bulb and eventually burn out the ballast while it continually attempts to light a higher wattage bulb.

 

[George Stolz]

Were these fixtures he provided for a new job that you installed?

No - there is a subdivision started a few years ago. Basically, monument signs were erected, a few houses were plunked down, and then the market crashed so building ceased. The company taking care of HOA property care and maintenance called us to fix some lights that were out, and that's where I entered the story.

It is nice to see building resuming in the neighborhood in question, though.

Edit to add: The reference to the supply guy was just me asking the stupid question of him that I asked of y'all when starting the thread - his reaction indicated that it was a stupid question and I should be ashamed of asking. I don't always believe supply guys, so I figured I'd ask here and check his facts.

 

[cadpoint]

Joules and Surge protection

Joules and Surge protection

wrong post sorry

 

[hardworkingstiff]

It is nice to see building resuming in the neighborhood in question, though.

Man, it's nice to see in any neighborhood. We need some of these "green shoots" to get growing.

Edit to add: The reference to the supply guy was just me asking the stupid question of him that I asked of y'all when starting the thread - his reaction indicated that it was a stupid question and I should be ashamed of asking.

Well I'd say he's the stupid one.

I don't always believe supply guys, so I figured I'd ask here and check his facts.

LOL, I don't always believe the supply guys either. There liability is usually to replace the part, that's the inexpensive side.

 

[hurk27]

As long as we're asking stupid questions and giving stupid answers I'm going to make a stupid assumption:roll:. I would think that a ballast that is rated for a specific wattage bulb (say 70 watts) would be able to handle the illumination of any wattage bulb up to the wattage that is being demanded (say 50-70 watts). The wattage of the bulb determines how much power is required to drive it. By the same token, if a higher wattage bulb were installed (say 80-100 watts), the wattage capability of the ballast would not be enough to illuminate the bulb and eventually burn out the ballast while it continually attempts to light a higher wattage bulb.

This would be true for a resistance load, but not an arc load, the smaller wattage arc tubes are shorter, requiring less arc current, and voltage to sustain an arc, raise the arc voltage that a higher wattage ballast produces and you have a very much higher current, this is also true when doing neon. tube of a given length will require a given voltage, go higher than the given voltage and the neon tube will cause a higher current on the neon transformer.

Now reverse this, place a larger wattage lamp on a smaller ballast, now the lamp is subject to a much higher open coil voltage, much higher than the voltage the lamp was design for, this can cause damage to the bulb, and or the ballast.