Mark Amundson had a gift for making technical details understandable to newbies without ever making the vets feel like they were being talked down to. His untimely death has left us with two holes to fill —one in our hearts, as we lost not only a writer but a dear friend, and another in the pages of FOH. Mark knew as well as anyone in this business that the show must go on, and we are just beginning the process of trying to find someone both willing and able to fill Mark’s very large shoes. For the next few issues, in a sort of tribute, we will re-run some of Mark’s own favorite columns. This one first appeared in FOH, Nov. 2007—ed.
Poor man’s power distribution is pretty much using the existing install venue power distribution, either because you do not have the moderate money to own a distro, the experience to use a dedicated portable power distribution unit (PPDU) or the venue does not easily accommodate the attachment of a PPDU. But have no fear, there are ways to maximize the existing available sub-circuits without calling in the electricians.
First and foremost, any poor soundco operator should have plenty of extension cords (service cords) to gain access to those far-flung receptacles that are on other subcircuits not in full use. I recommend plenty of 25-foot, 50-foot and 100-foot service cords of 12-gauge conductors with a type S (not SJ) jacketing. Also, once near the stage, some 10-foot or 15-foot breakout service cables with a quad-receptacle box are handy for backline and other shared loads on a 120 VAC, 20-amp subcircuit.
I have mentioned this before, but the NEC requires type S-rated (extra-hard service) service cords for lengths of 20 feet and beyond when used for live performances. Within 20 feet, you can use the more common type SJ cords found at most home improvement stores. But as a distro-poor soundco, you have to make up for this deficiency by having even more extension cords.
Well, one could always use the classic: Find the breaker panel, read the cryptic subcircuit names, trip-off the suspect breaker and search for the dead receptacles. Typically, in a working bar or club, this is a recipe for disaster, as you will likely choose the wrong subcircuits at the wrong time and probably get a stern talking to, if not booted out completely. But it does work great if you have the time and the venue is not in use. In the bad old days, you arrived Thursday night at bar-close to find the circuits for your Friday night gig. And, if you had an observer buddy and a two-way set of radios, this was done quickly.
Thankfully, today we have a modern device called a circuit sniffer that is used in conjunction with a circuit transmitter/buzzer. The transmitter is plugged into desired usage receptacles and creates a modulated amount of current draw on the hot and neutral wires all the way back to the breaker panel. To get the path, simply plug in the transmitter and go to the breaker panel with the circuit sniffer to find out which breaker buzzes the loudest. Finding each receptacle’s path may take some time, but will give you a clear layout of what subcircuits are in easy reach of the performance area. And if you are sure or brave, you can confirm your circuit choice by tripping the breaker and noting the removal of the buzz from the transmitter.
Referring to Figure 1, here are a couple of things you can do to help speed the circuit sniffing process. Most electrican’s wire venue receptacles are in daisy chains; in other words, they are series of receptacles all on the same circuit. If you are an astute observer of the venue’s receptacles and think like an electrician trying to wire the room for the first time, you may correctly guess that the receptacle farthest upstream chains back to the breaker panel. The reason for guessing your best regarding the farthest receptacle is that each downstream receptacle still has the buzzing current flowing through it, and the sniffer can be used near the suspect receptacles to pick up this buzzing. If there is a reasonably loud buzz, there is a very good chance it is on the same breaker.
Obviously, you can’t guess the layout perfectly, but in Figure 1, buzzing up subcircuit A will not cause buzzing in subcircuit B. However, by becoming a keen listener of your circuit sniffer, you can sometimes hear the buzz lightly in upstream receptacles. The rationale for this sniffing is to unobtrusively locate all the available circuits so you can run service cords back to the stage/performance area to power those amplifiers, consoles, backline and stage lighting. Obviously, stage lighting is first to be minimized if open subcircuits are in short supply. But others may differ with you on this.
