Posted on Aug 05, 2007 04:07 pm
glnflwrs
Head Knocker
Contributor Since: May 20, 2007
Edited Aug. 09...
See the extended update of this post by using the link on the home page of this site...
Taking the chance that there are a few who haven't had a lot to do with electricity, here are a few facts, etc. that everyone hooking up gear should know.
Source power:
Any electrical/electronic gear is going to use a certain amount of wattage, or power. It is usually spelled out on a sticker or plate that gives the input voltage, frequency or Hz, amperage, and watts. The watts is the important one as that IS what will be consumed. Watts equals (roughly) volts times amps. If you have a 120 watt light it will use one amp. 120v X 1a = 120Watts.
If the voltage is less than 120, the amps will go up to make up the 120watts.
Voltage up, amps down. Volts down, amps up. The gear uses watts, not volts or amps. So, if you use a 14 gauge wire (rated 17 amps max) for a 15 amp circuit, but you have only 109volts from the socket, the amperage will be more than 15 amps. It will exceed the 17 amps rating of the #14 wire and it will melt the insulation and short out, hopefully tripping the 15 amp circuit breaker for the building circuit you are plugged into. Lesson: Use #12 wire for all power cables to your gear unless you know for sure the voltage is a reliable and steady 120volt source.
Power supplies, surge suppressors, and line conditioners:
Audio gear is expensive, even the cheap stuff. It's also sensitive to fluctuations of voltage, surges caused by lightning or heavy equipment starting up, etc. The surge strips you buy for $10 at WalMart are OK for PCs because PCs use a specially designed power supply that protects against brownouts, shorts, surges, etc. But, the surge strips aren't worth a flip for a mixer that doesn't use a switching power supply, or a bank of power amps with fuse protection only. Also, when these surge strips do encounter a surge, the varistor that is the protection burns out, but the power keeps coming. You don't even know that it isn't protecting anymore unless it's one of the better units with an indicator.
To protect audio equipment properly and safely, an Isolating Line Conditioner is needed. This unit has a transformer that doesn't change the input voltage, but simply isolates the incoming power from the load with coils of unconnected windings. It also employs solid state "crowbar" circuitry that will soak up a surge of voltage, like lightning, or unrelated equipment loads, and store that extra power to give back if a brown out or severe voltage drop occurs. Essentially it maintains the input voltage within .1%. That's 120V +- .12V, or 119.88 - 120.12Volts. Very tight control, very good protection. A 1000KVA unit is standard and rackmountable, and has ten or more duplex 120v receptacles to plug power strips into. That size unit would power a good sized PA, mixer, rack FX, desk lighting, amps, amp stacks, etc. Two of those would do a Who concert.
Voltage drop: Basically, the longer the wire or cable, the bigger gauge it needs to be. Long cables soak up voltage, which causes amps to increase, which causes heat, and more voltage loss, and, eventually, total loss of signal. 25 feet of #14 might handle 15 amps. But 100 feet of #14 won't handle 10 amps at 120 V. Also, stranded copper is the only acceptable wire type for power cables. Solid wire won't flex and aluminum won't conduct as well.
There, that's the basics for safety. I'll rant on if anyone needs more than this.
dB, feel free to do with this whatever pleases you. Move it, delete it, edit it, it is yours. :)
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