Design Issues and Solutions -

[MNicolai]

Alright, so I'm looking for personal opinions here on an install I'm getting quotes for and planning. We want to project gobos onto the side of our building. There's a blank, light-grey, concrete precast wall that gives us enough room to toss a 30' diameter image on. It happens to our fly loft, and the facility is located on a hill, so it'll carry over nice to the nearby roadways.

There is an existing lamp post, 35 yards northwest of that face of the building, almost giving a perpendicular angle onto the wall. That doesn't even matter much, because we can get our gobos custom-made to include the keystone counter-effect. So far, I'm looking at the Clay Paky VIP 1200 to do the job, which can be equipped with a rain shield, color changer wheel, six-gobo rotating wheel, and long-throw lenses. I've also had a Martin fixture suggested to me that I have not looked very much into, but the sales reps are including in their alternates lists.

I want to control it with our existing Unison system, and set it up on an astronomical time clock to light up the exterior wall with our gobos, which will include a full-color, high-res, glass gobo with our logo, as well as cheap custom steel gobos for one-off events. So we can equip it with 6 gobos at a time, and 8 colors, including white. The color wheel is to give some extra pizazz to the otherwise black/white steel gobos. Inherently, the fixture does not strike/destrike via DMX, so I'm putting a DMX-controlled relay on the power feed to the fixture, which would be located indoors.

To isolate from lightning, I have planned to use fiber optics to transmit the data signal to the fixture, with data transceivers and ETC Net2 nodes on the receiving end, both located in an outdoor enclosure with 120v/15a power feed. This means that should our fixture, mounted on a 20' metal pole, get vaporized in a spectacular event, only the fixture, node, and transceiver get destroyed. Aside from that, the respective branch panel circuit breakers would be tossed, but Unison and other systems in the building would remain safe and isolated, with no path for electrical current to travel down the data lines in excess of 100,000 Volts.

However, control is where things get interesting. We want to be able to program the fixtures via ETC's LightManager software, which we're including the cost of training for. However, our original plan was to add 15 buttons worth of button stations to control colors, on/off, and gobos. We're including this in our quotes, but as I think about it, I'm not sure we'll need it.

If you had this setup at your venue, could you ever see yourself manually controlling the setup, or would you leave it entirely to Unison?

[icewolf08]

That sounds like one really expensive project! I would suggest programming some macros into unison but you could also get one of the customizable touch screen unison stations for controlling that fixture. Then all you have to do is build as many pages of buttons that you want into the interface. Pretty easy to do. Then you will have the choice of manual control or running something that is pre programmed.

[MNicolai]

By the way, we have a Unison Heritage system, not Paradigm.

The price came back on the stations, and it's only $500 more expensive to learn how to program in LightManager. Plus, cutting the stations means we don't have to run as much wiring and conduits.

[epimetheus]

Pardon the enthusiasm, but that sounds like a **** awesome project. I love solving problems like this. "You want to do what?!" Coming up with solutions to left-field problems is what keeps my day interesting. Granted, my left-field problems are generally how to stay under budget and still give the client what they want.

Fiber would be the way I would go for lightning protection. Having a device like that up in the air is going to make it a good target for lightning. Does the area have a lightning protection system? I wouldn't make the fixture the highest thing on the pole; some sort of sacrificial anode for lightning to actually strike might be something to look into.

[derekleffew]

While I applaud the forethought of lightning protection, I question the need for expensive fibre optic cabling and converters for this application. If an opto-splitter is involved, it already provides electrical isolation between its data inputs and outputs.

[MNicolai]

The advantage to fiber is that we don't need to bury another conduit for a low-voltage run for the DMX. We can run the fiber through existing line-voltage conduits without EM interference.

Our other option being of course to use wireless DMX. We have not had that alternative priced out yet because it was figured from the beginning to be expensive, versus running everything through existing conduits.

I did get the pricing back in full on the cost of adding button stations for manual control, and it's was scary expensive for something I don't know would see regular use. I scrapped that part of the project, which I'm especially okay with because that's one less conduit of wires we need to run.

For lightning protection, there are no existing lightning rods. If there were also lightning rods on that lamp post, I would be nervous that even if they did their job, the path of current would still arc across to the fixture. I will talk to my electrician about that though, however I don't know that either him or myself are exactly lightning experts.

At this point though, I have the pricing in on the equipment costs, but still have a question mark on the install costs. Our master electrician (in the literal, certified sense) is always very busy, but he's assured me he's going to hop on this ASAP. There's still a lot of uncertainty in this project though, because all it takes is for him to come back and say that there's not enough room to run the wires through the existing conduits, or that the fiber installation is going to unruly expensive.

He's got some headroom to work with though. I had a rough goal in my mind of getting everything done for about $15k, and so far we've only eaten up $9.5k. But electrical being what it is, could come back to be much higher than I'd like. I figure if we hit $17.5k, then we'll reexamine the costs for alternate ways of getting the data signal out there. I won't know much more until our electrician can price it out though.

The good news is that the higher ups all seem to be on board for this project as of now, so I hope to have an install complete before spring. As far as installs go, this should be a cakewalk anyways. I've already been informed we should only need an tech on site only for LightManager training and a couple minutes for configuring the Net2 node.

I'm going to get more info from the electrician on lightning protection, but if anyway here happens to be a resident expert, I would appreciate getting your input.

[Chris Chapman]

Mike,

You might also want to double check local ordinances concerning things that some might consider "illuminated signage" and how it deals with the nearby road way. It'd be a real pain if you got this all up and running and some knuckle head tries to shut it down because it doesn't comply with such and such local law.

Just a heads up.

-Chris

[epimetheus]

That's a good idea about checking local signage ordinaces.

How about wireless DMX? My church is going forward with a mostly LED-based upgrade in our current worship center. As part of this we're adding decent amount of fixtures on the floor as well as to our existing ceiling mounted positions. Our consultant included a wireless DMX system to get the floor units. While I'm not completely sold on this, I'm trying to keep an open mind. This would alleviate the lightning isolation issue as well as the possible conduit fill issue. Pulling fiber in a conduit is not exactly a easy task. You have to be careful not to exceed the bending radius and tension the fiber is rated for.

Please don't take me for an expert in lightning protection. It's just a thought that popped into my head. How tall are the buildings around this pole? Buildings offer protection from lightning to the surrounding objects.

Edit: As far as an opto-splitter providing lightning protection, I doubt it. Electrical isolation ratings in most devices, even ones that utilize optical isolation, don't exceed 1500V. If your pole were to get struck by lightning, there's a reasonable chance that voltage rise on a DMX line going out to it would see more than 1500V. Lightning is on the order 1,000,000V and >30,000A. No device can truly provide lightning protection. They key is having a system that shunts all that energy to ground before it can get into the electrical of data systems. Once that energy is on the electrical lines or data lines, you're screwed.

Specifically, in this case, since your ground path is most likely the electrical circuit and not a ground rod at the pole, I'd stick with a non-metallic signal path, either fiber or wireless. That's just me though, and I tend to err towards the side of paranoid caution these days. I would rather defend an over-designed system than have to explain why a system I designed failed.

[edmedmoped]

Originally Posted by epimetheus

Pardon the enthusiasm, but that sounds like a **** awesome project.

I can't think of a four-letter swear word that would make sense in place of the stars...

[epimetheus]

Think hydroelectric...