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Use regular Outlet for an M40, (4 replies and 2 comments)

1 week ago
lucasY75 1 week ago

Hello, Mr Deakins, I just discover this website while doing some research, and it look great, so first thank to take time to bring to light the question of person less experienced than you.

I work in the electrical department since I move into the US, and I discover recently that I can have 240v on a circuit by removing the neutral and remplace it buy a hot from an other circuit if there are not on the same phase.

so in the case where I cannot have access to stage pin connector or cam lock, if I'm using a M40, I should be able to plug it on two 120v, 20 amp circuit.

Does that will work without causing problems to the electrical ballast or any safety issues ? 

Thank for any information you can give me.

The Byre
1 week ago
The Byre 1 week ago

Bodging something together by placing it between phases is not something I would recommend - especially as you are obviously not a qualified electrician.  The very fact that you need to ask a question like that tells me that the answer is "Don't do it!"

Depending on how your lights are wired internally, yes, you can ruin them or even put the housing and lighting stands onto a phase - I've seen it done!  

Sorry to be blunt - but there is nothing quite as much fun as watching someone handling a lamp and then reaching out to a scaffold pole, only to be caught between two phases and nearly killing themselves.  At least some people thought it was fun because the guy in question was repeatedly told not to rig his lights that way.

1 week ago

Welcome to the forum, we are always happy to answer questions about filming and related subjects but your electrical question is not within the remit of the forum and is really a health and Safety issue, there are strict rules and legislation laws in the US
concerning TV and Film lighting and rigging so It is best to seek advice from a qualified service engineer. Your safety is our concern so please listen to “the Byre” and try not to ‘fry’ yourself experimenting just to save money. Doing it right only cost a few pennies more.

The Byre
1 week ago

Thanks Mike - If I may just add to the above, if Lucas is working between two phases on a three-phase supply, the resultant effective voltage (RMS) is not two-times 120V. Your multimeter may be showing you a value of 240V between the two phases, but that is the peak value will not be the true RMS value (root-mean-square) as you are (normally) getting two separate 120V supplies that are 1/3 of a waveform (120 degrees) out of sync with one another.

You can look up the mathematics on Wikipedia - it's all fairly straight-forward. Look-up the terms root-mean-square, three-phase and electrical ballast.

I do not know what type of ballast the lamp is using (and the word 'Ballast' covers a multitude of sins and devices used to limit current and otherwise control the electrical supply, each different!) so I cannot tell Lucas what if anything will be the damage done.

Knowing this stuff is bread-n-butter to any qualified gaffa, but even they, in times of a need to improvise, would never, I hope, try to put a light between two phases. As stated above - I've seen it done and the results were interesting, dangerous and very nearly deadly!

Roger Deakins
1 week ago
Roger Deakins 1 week ago

No! No! No! Do not do that!

7 days ago
Philipt 7 days ago

We do it all the time in location with 1.8s and it's no big deal. It actually can be considered safer because of the lower amps.

That being said, 4ks would be stretching it and no one does it. 4ks HMIs run at around 18 amps but it can go higher because of a variety of reasons. It could theoretically work.. but you'd need two 20 amps circuit.. and the whole thing would run hot.

You might as well get a oven or dryer tie-in with proper gaged wires. It's cheap to rent and simple to use. You plug the thing in the oven or dryer outlet, use the Y220 junction provided to get 220~240 volts with the proper connector for the ballast (bates in the US?).

If you are not sure, try to hire a good gaffer, he might even teach you how to lignt the scene!

Roger Deakins
7 days ago
Roger Deakins 7 days ago

Do not try this yourself unless you are a qualified electrician. That should be the end of the discussion on this web site!

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