Author Topic: Is it possible to plug a standard light fixture into a ballast?  (Read 1152 times)
RadiantMV
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Is it possible to plug a standard light fixture into a ballast? « on: April 11, 2021, 05:54:32 PM » Author: RadiantMV
I’m planning to get a 250 watt metal halide ballast for one of my bulbs. The bulb is going to be screwed into a lighting socket with cord and a mogul adapter. If i plug this cord with the bulb into the ballast, will anything bad happen? Do you need a specially made cord to be used with a ballast? Thanks!
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Rommie
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Re: Is it possible to plug a standard light fixture into a ballast? « Reply #1 on: April 11, 2021, 08:35:26 PM » Author: Rommie
It's possible, but ideally the ignitor needs to be as close to the lamp as you can get it, right next to the lampholder if possible. That way, the wiring between the ballast and fixture won't need to be pulse rated. With the ignitor at the ballast end of the circuit, it's a lot more difficult, the wiring and all the connections will need to be rated to withstand the pulse from the ignitor, possibly up to 5kV or so.

What I did was to build a small project box with the ignitor inside and the lampholder mounted on it, see below, but that might not work in your situation.
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Ria (aka Rommie) in Aberdeen
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Ash
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Re: Is it possible to plug a standard light fixture into a ballast? « Reply #2 on: April 11, 2021, 09:35:49 PM » Author: Ash
There are 2 risks in such setup :

1. Ignitor can cause an isolation breakdown. At ignition voltages that can reach to 5kV, Some other component of the setup - a cable, or some other component where there is not big distance on surface between 2 conductors, can not hold this voltage and fail by insulation breakdown. which is essentially fire

2. A short at the lamp output (for whatever reason, whether related to the ignitor or not) will be current limited by the ballast. If for example, a short happens at the wiring of a luminaire connected directly to the AC power (due to frayed wires), the resulting short circuit will trip the breaker immediately. If this happens on the output of a ballast, the current will be limited by the ballast so it can't trip any breaker, and will continue for unlimited time - With the addition of the ballast inductive characteristic that is very supportive of sustaining a stable arc. This risk exists even in setups without ignitor

So :

To mitigate 1, include the ignitor in the luminaire itself right before the lamp socket. Dont use any components that could fail from the voltage. (Ceramic sockets mostly aren't a problem, but an adapter could well be one)

To mitigate 2, verify that all wiring from the ballast on is in good condition, and generally avoid remote ballasts in "high fire risk" environments like bedrooms, living rooms etc

No problem if it is done only for a test
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Metal Halide Boy
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Re: Is it possible to plug a standard light fixture into a ballast? « Reply #3 on: April 12, 2021, 08:15:59 AM » Author: Metal Halide Boy
I’m planning to get a 250 watt metal halide ballast for one of my bulbs. The bulb is going to be screwed into a lighting socket with cord and a mogul adapter. If i plug this cord with the bulb into the ballast, will anything bad happen? Do you need a specially made cord to be used with a ballast? Thanks!

Is it to be probe-start or pulse-start? With Probe start you don't have to worry about starting pulses. But, I do not think a medium to mogul adapter is a good idea. I am worried it will melt from the heat of the bulb. Get a mogul socket. If your an adult you should be able to afford it. They run between $6 and about $20.
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Medved
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Re: Is it possible to plug a standard light fixture into a ballast? « Reply #4 on: April 12, 2021, 03:38:16 PM » Author: Medved
It may work, but it is definitely against the Code.
One of the general rules is to never use plugs/sockets interchangeable with those used for mains power for any system other than the mains power.
The reason is not if the connector would be electrically suitable or not (here assume it is as a matter of course), but the fact it could be accidentaly plugged where it does not belong.
That includes plugging the lamp directly into the mains power or a mains powered device into the ballast box.

So using e.g. European style mains sockets/plugs for the ballast->lamp interface in the US would be OK, as there the EU's plug you can not insert anywhere else and the same way you can not insert any mains device (assume they have only the US style plugs there) wont go into the ballast box.
The opposite, so the US type socket/plug for ballast->lamp interface in Europe would be a problem with the OCV and US sockets/plugs voltage rating and construction not preventing to touch partially inserted plug. But if the voltage rating would be sufficient (250VAC for probe start lamps), it would be OK.
Or using UK style sockets/plugs in continental Europe is OK, the same could be said when using continental sockets/plugs for the lamp ->ballast connection in the UK,...
The compliance is then valid for the whole set as a product (ballast box with socket plus the fixture with the plug together), so as a whole would needd compliance certification (per legal rules in the given country).

For home use you won't be looking for any certification, but I would strongly recommend to follow the rules about the protection agains accidental cable mix up.
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Rommie
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Re: Is it possible to plug a standard light fixture into a ballast? « Reply #5 on: April 12, 2021, 03:45:36 PM » Author: Rommie
It may work, but it is definitely against the Code.
One of the general rules is to never use plugs/sockets interchangeable with those used for mains power for any system other than the mains power.
I'm not sure that rule applies here, although I may be wrong. I use BS546 5A plugs and sockets, which can still be found in use in some older properties, for some of my discharge lamp boards (see here), although not usually where they have to handle high voltage pulses. As long as the equipment is not permanently wired to the mains, then you are perfectly free to experiment with anything you like that connects to the mains by means of a standard 13A plug. All the stuff I build is for our own personal use and is never left unattended, so I think we're ok.
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Ria (aka Rommie) in Aberdeen
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joseph_125
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Re: Is it possible to plug a standard light fixture into a ballast? « Reply #6 on: April 12, 2021, 03:53:07 PM » Author: joseph_125
The most code compliant solution for the plug would be to probably use one of the various grow light plugs and cables available. They're pretty much designed for the purpose of plugging a remote ballast to a non ballasted luminaire.

If mixing the plug is the only concern, there are plenty other plugs that you could use. For example the NEMA 6-15 pattern for 240v 15A or the NEMA L5-15 twistlock plugs. These plugs are for more specialty applications though so your typical home user is unlike to possess anything else that uses those plugs. It's technically not code/UL approved to use the plugs in such a manner so bear that in mind.

Now the stuff I build is for personal use so I do use standard 15A plugs but if you do use them it's at your own risk. 
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Rommie
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Re: Is it possible to plug a standard light fixture into a ballast? « Reply #7 on: April 12, 2021, 04:03:18 PM » Author: Rommie
I got an error message on that page:

Error 1020 Ray ID: 63ef0c18ef16077e • 2021-04-12 20:01:33 UTC
Access denied
What happened?

This website is using a security service to protect itself from online attacks.

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Ria (aka Rommie) in Aberdeen
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joseph_125
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Re: Is it possible to plug a standard light fixture into a ballast? « Reply #8 on: April 12, 2021, 04:36:37 PM » Author: joseph_125
Hmm maybe a IP geoblock? The site still works fine for me.

Anyway here's a similar picture of one of those plugs.
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Rommie
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Re: Is it possible to plug a standard light fixture into a ballast? « Reply #9 on: April 12, 2021, 04:44:22 PM » Author: Rommie
Those look interesting. Apart from the BS546 plugs and sockets, I sometimes use straightforward IEC connectors as you get on a lot of equipment. I have power leads with IEC C13 connectors on one end, and UK BS1363 13A plugs, or NEMA 5-15 plugs, or Schuko plugs on the other, so I can plug into just about anything. I might want to plug into my US 120V 60Hz inverter or UK mains, so it's all about flexibility.
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Ria (aka Rommie) in Aberdeen
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Medved
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Re: Is it possible to plug a standard light fixture into a ballast? « Reply #10 on: April 13, 2021, 03:07:10 AM » Author: Medved
I'm not sure that rule applies here, although I may be wrong. I use BS546 5A plugs and sockets, which can still be found in use in some older properties, for some of my discharge lamp boards (see here), although not usually where they have to handle high voltage pulses. As long as the equipment is not permanently wired to the mains, then you are perfectly free to experiment with anything you like that connects to the mains by means of a standard 13A plug. All the stuff I build is for our own personal use and is never left unattended, so I think we're ok.


The main purpose is to avoid accidental mixup. The fact there are only you two who will be ever using it, is not enough.
Belive me, the first one connecting it wrong if it would be physically possible, would be mainly you. Sooner or later...


So if some socket/plug type is not used for mains anymore, there is no problem using it for the lamp. The fact wheter it was ever used in the past for the mains does not matter, if it is not on any mains power anymore.

Of course, using a connector type which is common for the task is the best - even when someone find later on only part of it (e.g. the lantern), it would be clear "Hey, there must be a ballast box for it somewhere"... 
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Rommie
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Re: Is it possible to plug a standard light fixture into a ballast? « Reply #11 on: April 13, 2021, 09:07:45 AM » Author: Rommie
The main purpose is to avoid accidental mixup. The fact there are only you two who will be ever using it, is not enough.
Believe me, the first one connecting it wrong if it would be physically possible, would be mainly you. Sooner or later...

Well we'll have to agree to disagree on that one. I'm a creature of habit and I've been doing things mostly the same way (hopefully with improvements here and there) for over 50 years. Of course that can make people complacent, but I haven't killed myself or anyone else yet.
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Ria (aka Rommie) in Aberdeen
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