Lighting dimmers are a pretty simple concept, they are used to increase or decrease voltage to a dimmable lighting fixture in order to adjust its intensity. Typically used with incandescent halogen or specific kinds of fluorescent fixtures, dimmers give us the flexibility to set the mood and/or focus attention. By adjusting the voltage sent to the fixture, a dimmer can turn the light on, off or anywhere in between. As anyone who has house lights that only turn on or off can tell you, dimmers play a valuable role in great lighting.
Quick Power Lesson
Before we dig into the types of dimmers available, it's important to have an idea of how much power these dimmers will need. While portable/distributed dimming generally will work with a 20 amp circuit, most dimming packs will need much more. Here's how you can do the math. Very simply, 20 amp circuits equate to 2400 watts of power. If you break it down, that means for every 600 watts you have, you need 5 amps. A 12-channel, 1200 watt-per-channel dimmer then will need 120 amps to power it all. All in all, once you get into larger dimming set-ups, an electrician MUST be involved to ensure proper electrical distribution. Unless you are a licensed electrician, please do not take this role on yourselves.
Four Styles of Dimmer Packaging
A dimmable switch is dimming at its simplest form. While not terribly user friendly for theatrical uses, if you have a super small lighting rig (maybe 4-8 lights) and this is all you can afford, it sure beats an on/off switch. Unfortunately, your lighting console can't control these dimmers, so you have to dim lighting "manually". These dimmers also have inferior filtering. They are designed to fit into a small electrical box, therefore the "choke" or "filter" that helps filter out noise is also very small. That can often result in noise problems for your sound system and even your video system. Use dimming switches only as a last resort.
Portable dimmer packs consist of several independent dimmers packaged into one chassis. The number of channels per pack can be as low as 4 and as high as 24. 4 channel packs are very popular since they typically can plug into a 20 amp circuit, which is the standard for newer commercial building wiring. Older churches often have 15 amp circuits so you need to check your wiring and circuit breaker panel first before you decide on which dimmer to order.
For smaller venues where dedicated 20 amp circuits are readily available and for smaller portable setups, portable dimmers make a lot of sense. You can usually control 4 lights independently with load power for each light up to 600W. That means a 500W Par Can is perfect to use with this type of dimmer. If you plug in a 500W Par into each of the 4 channels, the total load is 2000W. Since each 20A circuit can supply 2400 Watts, the total load is under the total supply of the 20A circuit, even with all four fixtures at full power.
With portable or distributed dimming, the power is already near the fixtures, so wiring the fixtures to the dimmer is easy. You simply plug the fixtures into the dimmer or use a short extension cord. With the dimmer near the fixtures, you only need to run on heavy duty cable from your 20A outlet to the dimmer pack. Now you just need something to control the dimmer pack. Newer portable dimmers are generally DMX controlled, so if you address your standard portable dimmer to DMX address 1, it will receive DMX and control intensities for channels 1-4.
Portable/Distributed dimming comes in a variety of shapes, sizes and price points. A variety of manufacturers make 4 channel dimmer packs, such as American DJ's DP-DMX-20L, which you would generally hang from your lighting pipe with a standard lighting clamp. A sleeker, more elegant solution is the ETC Smartbar 2, giving you the same function in a bar-style solution that you can also mount your lights to if you choose. Ultimately, there are various options available in different form factors (and at different price points), but they all essentially accomplish the same thing, regulating voltage to the fixtures at your control.
When building a new or retrofitting an existing building, generally people prefer a cleaner look without portable/distributed dimmers hanging throughout the room. In this case, instead of distributing the power to where the lights and dimmers will hang, we bring all of the power into one central location where dimmers are installed, and then distribute the controlled power to their final destinations. The first option that allows us to do this is a simple Dimmer Pack, typically rack or wall mounted. The packs often come in 6 or 12 channel versions and can range all over the map on how much power they offer per channel. For example, the ETC Smartpack SL1210-W offers 12 channels of dimming per pack with 1200 watts per channel. Other models might offer 6 channels of 2400 watts per channel, and others up to 12 channels of 2400 watts per channel. You would then build a rack of dimmer packs or install a wall-mount version to give you the number of dimmable channels you need and then distribute the power from the packs to your final fixture destination.
In larger installations, needing anywhere from 48 channels and up, you will often get into much larger dimmer racks, which offer much more distribution, power and flexibility. Just like our other options above, they provide varying amounts of power distributed to lighting fixtures for dimmable operation (typically either 1200 or 2400 watts per channel). Unlike our other options though, their dimmer modules, generally in pairs of channels, are swappable giving some flexibility in what you can provide power-wise. You can also replace dimmer modules with relay modules, giving you the ability to turn things on and off without the danger of browning them out by feeding them a partial voltage.
If your church is one that still runs their lights with on and off switches, hopefully this walk through dimmers has helped alleviate fears or concerns you've had converting to dimmable power for your lighting. With conventional lighting, dimming is really a critical piece to making your lighting work for you in creating the mood that you want, or bringing focus where you want it. If you'd like to discuss adding, upgrading or replacing dimmers at your church, we'd love the opportunity to serve you!