National Electrical Code Top Ten Tips:
Article 650 -- Pipe Organs
Not very many electricians perform installations of pipe organs. Today, you find these massive instruments almost exclusively in church house sanctuaries. But not only are people dropping out of religions all over the world, those who stay attend less and provide much less money to their church. Reduced attendance and pinched financing are a couple of reasons this equipment is on the decline. Another is many churches, especially the mega churches, are opting for other musical instruments such as guitars and electronic synthesizers.
Still, it's hard to beat a pipe organ when heart stirring is the goal. So these will be around for a while, yet.
- A pipe organ drives pressurized air through pipes [650.2]. This gives it acoustal properties not possible with a piano.
- In a given location, you may also need to apply Article 640. For example, the church isn't relying only on a pipe organ. They also have a synthesizer and an audio processor (with inputs for electric guitars).
- Some of these music systems also use fiber optic cable; in those cases, Parts I and II of Article 770 apply [650.3(B)].
- For the pipe organ and its associated equipment (see Scope in 650.1), you must supply DC power using a listed DC power supplyl with a maximum output of 30V [650.4].
- If the aforementioned DC power supply is not double-insulated, then you must ensure the metallic case of that supply is bonded to the input equipment grounding conductor [650.5]. This will allow undesired current to flow back to the source instead of through the electronic equipment.
- The minimum conductor size for the electronic signal circuits is 28AWG [650.6(A)]. This is a tiny conductor. Take care to route these away from power conductors as much as possible, especially any 120V AC conductors that are in the wall or floor. Other minimums are 26AWG for the electromagnetic valve supply (and related), and 1AWG for the main common-return conductor in the electromagnetic supply. These Code minimums do not ensure performance or reliability [90.1], so wherever practical use larger conductors than the NEC minimum.
- Most of the conductors must be cabled [650.5(C)]. Take care to route the cables in such a way as to prevent kinking them or exposing them to mechanical damage. And remember, a neat installation really isn't optional. It's what distinguishes a professional from a hack.
- Part of a neat installation involves following the requirement to securely fasten the conductors in place [650.7].
- Conductors sized at or between 20AWG and 28AWG must be protected by an overcurrent device rated at no more than 6A. Protect other conductors based on their ampacity [650.8]
- Keep the wiring within the lockable enclosure (the organ chamber) [650.9].