Running a Follow spot through our dimmer rack

[willbb123]

I sent an email to a local ME but I thought I'd get good responses here too.
For an upcoming show the renters want to put 2 of our follow spots in two of our box booms. There is not a 20a circuit anywhere close to the position. We have plenty of open dimmer circuits in the box. We have two Constant Current Units that we can use. So the spotlight would not be running through a dimmer.
They are Lycian follow spots, on the ballast it says its rated for 20a. The Sensor + constant current units are rated at 20a. I would have to put a 20a plug on the 3pin to Edison converter.
The thing I am worried about is pulling too much from one leg. The circuits would not be next to each other, so in theory I can put them on different legs.

Is it alright to run the spotlights through the dimmers? Or should we run dedicated circuits to the boxes?

[derekleffew]

The exact model of Lycian followspot would have been helpful information, but assuming it's a 120V unit (1209, 1266, 1271, etc.)...

Originally Posted by willbb123

...We have two Constant Current Units that we can use. So the spotlight would not be running through a dimmer. ...

Originally Posted by willbb123

...Is it alright to run the spotlights through the dimmers? ...

If you're using ETC CC-20 modules, you're not running the followspots through the dimmers. You are running them through the dimmer rack, but they are not on a dimmer.

Originally Posted by willbb123

...They are Lycian follow spots, on the ballast it says its rated for 20a. The Sensor + constant current units are rated at 20a. I would have to put a 20a plug on the 3pin to Edison converter.

What input connector is on the ballast now? Just use the mating female connector on your 2P&G to (NEMA 5-15?) adapter.

Originally Posted by willbb123

...The thing I am worried about is pulling too much from one leg. The circuits would not be next to each other, so in theory I can put them on different legs. ...

A 20A differential will not even be noticed in any dimmer rack larger than 12x2.4kW. If this is an installed rack, the feeder was sized with load diversity in mind. Unless your input power is severely undersized, you needn't worry.

[icewolf08]

I second Derek. We run followspots through our racks all the time using CC-20 or R-20 modules. Either way it is not a dimmer and thus it works fine. Just remember that if you use R-20 modules that oyu need to park them on or make sure they stay on for the entire show or you might have some angry spot ops!

[JD]

You can run a followspot on a constant on module (as in breaker only) but do not run them on a SSR or other solid state module. When the igniter fires, it can "backfire" through the ac cord. No problem whatsoever as long as the device is in conduction at the time, but if you are unlucky enough for the SSR to be at ZVC (and thus "off") when the flyback voltage hits, then you will cook the device due to overvoltage. This is true only on magnetic ballasts that use series PF caps as compared an input parallel PF cap.

[porkchop]

Model would still be a good thing to give us, Lycian makes a few model numbers that can be several voltages. I know with the 1290XLTs if you only have 20A you need to have them on 208V - 240V service where they can also run at 120V but only on a 30A service. I doubt if you're running through the box booms that your lights are that big (you'd probably melting performers onstage) but still it's a good thing to check.

[willbb123]

Thanks for the responses.
The spots are Lycian 1271. They all run off 120V.
The two in the booth have been running for years with 15A plugs. I am going to upgrade all of them to 20A plugs first chance I get.

[FatherMurphy]

Changing the connectors and outlets to 20A is probably not necessary, especially if it's been behaving politely for years already. The unit might draw more than 15 amps at strike, but once the arc is established it should drop under 15 amps - Lycian shows that unit as being a 1200 w HMI lamp. If there isn't an amp meter on the unit, you could get a clamp-on meter and check that way.

Call me at work if you can't find one in IC (I did a power tie-in for you at the children's museum a month or so ago, if you haven't figured out who I am), and I'll dig one up for you to borrow.

[willbb123]

Originally Posted by FatherMurphy

Changing the connectors and outlets to 20A is probably not necessary, especially if it's been behaving politely for years already. The unit might draw more than 15 amps at strike, but once the arc is established it should drop under 15 amps - Lycian shows that unit as being a 1200 w HMI lamp. If there isn't an amp meter on the unit, you could get a clamp-on meter and check that way.

Call me at work if you can't find one in IC (I did a power tie-in for you at the children's museum a month or so ago, if you haven't figured out who I am), and I'll dig one up for you to borrow.

Holy Cow... I know someone on the forum!!! I sent you a PM by the way.

Once I've realized that they were only 15a, I struck (striked?) the lamp and let it run for like 3-5 min. The prongs were hot, and I regretted touching them (not hot enough to burn). Also the first foot or so of cable was warm. The heat could of just been from striking, I've never tested after it had been on for a show.

I would feel safer with 20a plugs, but if its not necessary we wont get it.
I've got a few weeks before they are needed again, so I will have time to test it.

[FatherMurphy]

Corrosion on the blades, or loose connections inside the plug could also cause the heat. Was reading a post here recently to the effect that there isn't any more copper in a 5-20 edison than in a 5-15 (the different blade config was to prevent 20A devices from being plugged into 15A breakers), which adds to my doubts that amperage alone is a problem here.

See you tomorrow, perhaps.

[derekleffew]

Originally Posted by willbb123

...I would feel safer with 20a plugs, but if its not necessary we wont get it. ...

It has yet to be proved to me that the NEMA 5-20 plug contains more conductive material or surface area than the NEMA 5-15. Furthermore, I know of no 120V followspot that comes from the manufacturer with anything other than a 5-15 plug (speaking only for US practices).