# Completed ProjectCan I run a Mercury Vapor Lamp of lower wattage (400W) on a 1000W MHL ballast?

#### Rahulk70

Joined Dec 16, 2016
511
Hi folks,

I've received a M1000MLTAC5M Metal Halide 1000W ballast. The picture of the label on the ballast and a spec sheet has been attached for reference.

My first question is can a mercury lamp be used with this ballast? If yes, does it have any short comings here? The person who gave it to me said this ballast has been used with MVL and MHL. Can I used this 1000W ballast with a 400W mercury lamps? Is it like that the lamp would draw only the required wattage from the ballast? Or is it like the ballast would pump 1000 Watts into the bulb and go boom!?

Also this ballast is for 60Hz. So, if I were to run it (240V/277V wiring) on a European 230V 50Hz supply will it damage the ballast or lamp? The european ballasts out there on eBay are like $60-80 and the shipping itself costs like$110. Not worth it. Though the bulbs are quite cheap.

Link to the video running the ballast only and taking the open circuit readings.

Update: Sorry for making this late change. I have edited the question to reflect the new ballast that I've just received and I'm planning to install this outside my home.

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#### DickCappels

Joined Aug 21, 2008
6,950
Yes, you can, BUT though I do not have direct experience with those lamps but I suspect that running a higher power ballast would shorten the life of the lamp significantly.

#### Rahulk70

Joined Dec 16, 2016
511
Yes, you can, BUT though I do not have direct experience with those lamps but I suspect that running a higher power ballast would shorten the life of the lamp significantly.
Hi,
Thanks for the info. I was hoping that since the ballast is a 400W type, using a lower wattage bulb would only draw the current it requires from the ballast. But from your explanation it seem sthat the ballast would pump the current for a 400W bulb into a smaller lamp and destroy it.

#### RichardO

Joined May 4, 2013
2,271
When I looked at specifications for some fluorescent lamps I have, I found that they were at about 40 volts when fired. The ballast is just a large inductor that limits the current to the lamp which is more-or-less a short when fired. Since it is an inductor, the current it will limit to is dependent on the line voltage and frequency.

#### ebp

Joined Feb 8, 2018
2,332
To elaborate on Richard's post:

Because the voltage across the lamp is relatively independent of nominal lamp power, the power can only be varied by controlling the current. A ballast with reactance appropriate for a 400 W lamp will allow around four times as much current as one for a 100 W lamp, with unhappy consequences for the latter if used with a 400 W ballast.

#### Rahulk70

Joined Dec 16, 2016
511
Hi everyone,

First I apologize for the update. I didn't want to post another question with same content again and spam. So, I've instead updated the question slightly.

#### Rahulk70

Joined Dec 16, 2016
511
To elaborate on Richard's post:

Because the voltage across the lamp is relatively independent of nominal lamp power, the power can only be varied by controlling the current. A ballast with reactance appropriate for a 400 W lamp will allow around four times as much current as one for a 100 W lamp, with unhappy consequences for the latter if used with a 400 W ballast.
Well in that case I think I've no option but to just use the correct wattage of lamp itself. Also this ballast doesn't seem to need an ignitor. My only confusion now is can I use a Mercury Vapor Lamp 1000W on this ballast?

#### Alec_t

Joined Sep 17, 2013
11,867
since the ballast is a 400W type
No. It says 1000W on the label, so its inductance will present a reactance at 60Hz suitable to limit current to a 1000W-rated lamp. A 400W lamp would need a higher reactance. Also, reactance is proportional to frequency, so running on 50Hz instead of the rated 60Hz would pass more current to the lamp. Even a 1000W lamp would get more than its designed current if you use 50Hz.
Also this ballast doesn't seem to need an ignitor.
The label referes to grounding of a metallic ignitor.

#### Rahulk70

Joined Dec 16, 2016
511
No. It says 1000W on the label, so its inductance will present a reactance at 60Hz suitable to limit current to a 1000W-rated lamp. A 400W lamp would need a higher reactance. Also, reactance is proportional to frequency, so running on 50Hz instead of the rated 60Hz would pass more current to the lamp. Even a 1000W lamp would get more than its designed current if you use 50Hz.

The label referes to grounding of a metallic ignitor.
Hi,
So, I'll be using only a 1000W lamp with it. Is it okay to use mercury lamp with this ballast? The electrician who gave it to me said they used it with mercury lamp as well as metal halide and it was okay. But I just want to be sure.

I'll get another 50Hz ballast. Seems to be only choice here. Or run it from my 5000W 115V 60Hz inverter.

#### MisterBill2

Joined Jan 23, 2018
7,964
Mercury vapor lamp bulbs have an internal ignitor electrode, so it is not an external one. The grounding is for radiated noise reduction, because a mercury arc can generate a whole lot of electrical noise. Also for safety, as that open circuit voltage can deliver a very bad shock. So hands off while the power is on.

#### Rahulk70

Joined Dec 16, 2016
511
Mercury vapor lamp bulbs have an internal ignitor electrode, so it is not an external one. The grounding is for radiated noise reduction, because a mercury arc can generate a whole lot of electrical noise. Also for safety, as that open circuit voltage can deliver a very bad shock. So hands off while the power is on.
So, from a little googling I found that there are two types of lamps Probe-start (175-1500W) & Pulse-start ( 175W & below). Yeah from the spec sheet I saw it can reach quite high voltage during the start-up. What got me confused was the label on the ballast which said ground the ballast, ignitor & cap case. But the spec sheet said ignitor isn't needed.

#### MisterBill2

Joined Jan 23, 2018
7,964
So, from a little googling I found that there are two types of lamps Probe-start (175-1500W) & Pulse-start ( 175W & below). Yeah from the spec sheet I saw it can reach quite high voltage during the start-up. What got me confused was the label on the ballast which said ground the ballast, ignitor & cap case. But the spec sheet said ignitor isn't needed.
That is something that I find a lot: one set of instructions that are supposed to cover all of the products. They are so general that they are useless. If you examine a bulb closely you will see that on that inner part where the actual light is produced, at one end there is an additional electrode. That is the starting probe, it provides a short spark to the nearby electrode to start heating the mercury to vaporise it.

#### Rahulk70

Joined Dec 16, 2016
511
That is something that I find a lot: one set of instructions that are supposed to cover all of the products. They are so general that they are useless. If you examine a bulb closely you will see that on that inner part where the actual light is produced, at one end there is an additional electrode. That is the starting probe, it provides a short spark to the nearby electrode to start heating the mercury to vaporise it.
Yes, I absolutely agree with you. Sometimes the generalization causes a lot of confusion. I took the readings as shown in the video. For safety purpose I used the input supply my 500W 115V bench UPS supply that I had made for such experiments. The input current draw was 2.5 - 3A and the output voltage was 360V and occasionally it pulses after a while too 400V.

#### Janis59

Joined Aug 21, 2017
1,257
Answer is strict NO. Lamp will overheat in few minutes. Its experimented well. You may use or TWO identical 1000W ballasts in serie or apply the long-lamps ballsats parallely (typical 40W or 65W or 80W in respective count), or just use the electric cooker, electric ironing or anything else let only current would correspond to 400W. The current is those thing You must warranty via the lamp.

#### Rahulk70

Joined Dec 16, 2016
511
Answer is strict NO. Lamp will overheat in few minutes. Its experimented well. You may use or TWO identical 1000W ballasts in serie or apply the long-lamps ballsats parallely (typical 40W or 65W or 80W in respective count), or just use the electric cooker, electric ironing or anything else let only current would correspond to 400W. The current is those thing You must warranty via the lamp.
I ha e decided that I’ll get only a 1000W. Especially since I heard the MH lamps explode at EOL. So, things could go wrong. Now I’m just confused if it’s okay to use a Mercury lamp 1000w with this ballast.

#### MisterBill2

Joined Jan 23, 2018
7,964
I have replaced quite a number of 175 watt bulbs in the past 2 years and since they no longer light, I assume that is E.O.L.. Black and discolored on the inside of the inner bulb, but no explosions at all. Of course, if you run a low wattage bulb on a high wattage ballast "Your results may differ", like some instruction sets warn. I can't imagine any organization selling lamps that would ever explode without rather severe abuse, simply because of the liability issues.

It would be interesting to hear if anybody has experienced exploding bulbs.

#### Janis59

Joined Aug 21, 2017
1,257
I am using the bulbs carefully crushing the exterior bulb let the only interior quartz ampule stays alive. Its extraordinary good mold killer device. Thus, for years I used 800W russian lamps DRL800, but then the stock was cut so the rest I have DRL-400. In the first minutes of work, if the ballast is not corrected, they overheat to change the form and dehermetizes with a bubble in midst column. Its not ok to have a mercury vapour in any room. It will smell a many hundreds of years afterward.

Just adjust the current measured on live lamp pass to datasheet and never shall see the problems.

#### MisterBill2

Joined Jan 23, 2018
7,964
I am using the bulbs carefully crushing the exterior bulb let the only interior quartz ampule stays alive. Its extraordinary good mold killer device. Thus, for years I used 800W russian lamps DRL800, but then the stock was cut so the rest I have DRL-400. In the first minutes of work, if the ballast is not corrected, they overheat to change the form and dehermetizes with a bubble in midst column. Its not ok to have a mercury vapour in any room. It will smell a many hundreds of years afterward.

Just adjust the current measured on live lamp pass to datasheet and never shall see the problems.
This is very interesting, in that I was not aware that anybody had done that. I am certain that the intense ultraviolet would indeed kill mold, germs, and most bacteria. But probably it is unsafe for humans and other animals, and the hot ampule will require a great deal of caution handling it. So don't let the OSHA folks find out that you are doing it. But it certainly is an interesting concept that I had not considered. Thanks for posting it.

#### Rahulk70

Joined Dec 16, 2016
511
This is very interesting, in that I was not aware that anybody had done that. I am certain that the intense ultraviolet would indeed kill mold, germs, and most bacteria. But probably it is unsafe for humans and other animals, and the hot ampule will require a great deal of caution handling it. So don't let the OSHA folks find out that you are doing it. But it certainly is an interesting concept that I had not considered. Thanks for posting it.
That is indeed very unsafe. The lamp temp gets around 550C at full blast. Without the outer glass envelope you get exposed to this heat plus all the harmful UV rays if any present too.

#### Rahulk70

Joined Dec 16, 2016
511
I am using the bulbs carefully crushing the exterior bulb let the only interior quartz ampule stays alive. Its extraordinary good mold killer device. Thus, for years I used 800W russian lamps DRL800, but then the stock was cut so the rest I have DRL-400. In the first minutes of work, if the ballast is not corrected, they overheat to change the form and dehermetizes with a bubble in midst column. Its not ok to have a mercury vapour in any room. It will smell a many hundreds of years afterward.

Just adjust the current measured on live lamp pass to datasheet and never shall see the problems.
In the above video at 115V from the UPS supply the current draw is only around 3A when the spec on the ballast says it should be around 8.95A at 120V which is around 1000Watts, but in my case its only like 350Watts. The 400W bulb I have is an Audex 400W MH-BT.

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