Although the musicians we work with can be trying at times, and occasionally less than pleasant thoughts regarding them cross our minds, I seriously doubt that watching them fry from high voltage is something we would want to be responsible for. This article will give you some basic precautions and tests to reduce if not eliminate the possibility of electrocuting our musical friends.

Finding Common Ground

It is of the utmost importance that the console with the shortest snake distance to the stage uses the same AC ground as the backline power. Let me clarify and explain. Microphones are grounded by the “pin 1’s” of the snake and ultimately, the console(s) that your snake is plugged into. The console closest (by closest I mean “cable length”) to the stage should not be pin 1 lifted. All microphones short pin 1 to the casing of the mic itself. This “close” console provides the critical ground to your microphones.

By “same AC ground” I mean that the backline power should come from a circuit that shares a common close proximity ground with the “close” console. If you have a separate stage console, it should be plugged into the same AC distro as the backline. If you have just a single console setup, the same thing applies. The majority of buzz, hum and shock problems exist when people setting up the system use a convenient outlet rather than make sure that backline and consoles all use circuits with close proximity grounds.

Don’t Even Think About It

If you were to AC ground the absolute minimal amount of things in your system it should be your stage console (FOH in one console systems) and backline power. I don’t want to get sidetracked into the various system grounding techniques but I will say that you can pretty much AC lift anything you want with minimal adverse effects as long as you ground the closest console to stage and backline power. This is not to say that AC lifting various pieces of gear will not present potential hazards and I am in no way recommending that you AC lift gear (at least in this article) but solving ground loops often presents a bit of a dilemma. You want the hum to go away, you know AC lifting is not the safest thing to do yet cutting pin 1 on every loom to a rack is not only impractical but may not even solve the particular problem. I realize there will be some AC ground lifting going on.

Dealing With the Unknown

One of the more difficult things to get a handle on is the grounding and safety of the backline gear itself. Unlike the sound system, it’s pretty much something that you often have little or no control over. The affinity over “vintage” gear combined with multiple amp setups can often present quite an unwieldy situation. Though I can’t cover all the possible configurations, I can give two rules of thumb that help keep your musician alive.

1) Whether there is one or multiple guitar (or bass) amps all connected together, at least one piece of gear in the signal chain must be AC grounded, preferably the one that the guitar (or bass) plugs into or the closest (shortest cable length) one.
2) When you encounter the vintage amp with a non-polarized ungrounded plug, pay extra attention to how it is plugged in, it is best to mark it. Actually it’s best to replace it! These are the AC plugs that don’t have the “fat” and “skinny” flat blades, both blades are “skinny”. On all modern ungrounded plugs the “fat” blade is neutral and the “skinny” blade is hot, therefore making it so the plug cannot be reversed.

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