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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => The Basement => Topic started by: Scott Stephens on March 29, 2014, 02:42:11 PM
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Hey, guys,
If I have an amplifier with a 20 amp plug and with a little converter cable/adapter reduce it to a 15 amp plug, how much power am I losing?
I am losing enough to affect sub or top performance? I assume a little, but is anyone going to notice? Will I still kick a breaker?
Just wondering. Thanks
scott
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Hey, guys,
If I have an amplifier with a 20 amp plug and with a little converter cable/adapter reduce it to a 15 amp plug, how much power am I losing?
I am losing enough to affect sub or top performance? I assume a little, but is anyone going to notice? Will I still kick a breaker?
Just wondering. Thanks
scott
You are not "losing power." Performance will be affected only if you trip the breaker.
In a commercial space, a 15 amp receptacle should be protected by a 15 amp breaker (Grandfathered in; current Code permits only 20 amp circuits in commercial occupancies). In your home, a 15 amp receptacle can be on a 20 amp breaker if wired with #12.
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You are not "losing power." Performance will be affected only if you trip the breaker.
In a commercial space, a 15 amp receptacle should be protected by a 15 amp breaker (Grandfathered in; current Code permits only 20 amp circuits in commercial occupancies). In your home, a 15 amp receptacle can be on a 20 amp breaker if wired with #12.
Always remember as well that it *IS* possible to burt out 15A plugs/outlets if you pull too much power through them. Earlier in my life, I burned out several cheap-o molded extension cords when trying to run bunches of parcans. Whoops!
-Ray
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Always remember as well that it *IS* possible to burt out 15A plugs/outlets if you pull too much power through them. Earlier in my life, I burned out several cheap-o molded extension cords when trying to run bunches of parcans. Whoops!
-Ray
You were grossly overloading that extension cord, and the point of greatest resistance (and heat) is at the connections. It was also not listed for the use. Ray, this is why we have rules.... <shakes finger at Ray>
IIRC, the reasoning behind protecting a 15a outlet with a 20 amp breaker is that no current consumer appliance draws over 15 amps, and adding another high current appliance would (should) trip the 20 amp breaker.
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IIRC, the reasoning behind protecting a 15a outlet with a 20 amp breaker is that no current consumer appliance draws over 15 amps, and adding another high current appliance would (should) trip the 20 amp breaker.
Unless it's a FedPac breaker. :o
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You were grossly overloading that extension cord, and the point of greatest resistance (and heat) is at the connections. It was also not listed for the use. Ray, this is why we have rules.... <shakes finger at Ray>
I know I know I know! That was "back in the day," when I was just getting my foot in the Live Sound door. It was at a Relay for Life, if I remember right. Heh. So event already wasn't paying much, and I learned something new at the School of Hard Knocks.
So, yes, they weren't rated for such use. And I didn't know that. And I learned the consequences, as well as how to determine the load that I was going to experience with the setup I would be using. Since then, I've not had the problem occur again. I just wanted to point out to the OP that it's still possible to burn things out even if you're on a 20A breaker and it hasn't tripped yet.
-Ray
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I know I know I know! That was "back in the day," when I was just getting my foot in the Live Sound door. It was at a Relay for Life, if I remember right. Heh. So event already wasn't paying much, and I learned something new at the School of Hard Knocks.
So, yes, they weren't rated for such use. And I didn't know that. And I learned the consequences, as well as how to determine the load that I was going to experience with the setup I would be using. Since then, I've not had the problem occur again. I just wanted to point out to the OP that it's still possible to burn things out even if you're on a 20A breaker and it hasn't tripped yet.
-Ray
Besides, everyone loves the smell of vinyl chloride in the morning. ;)
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Unless it's a FedPac breaker. :o
Yes, this is why Federal Pacific Electric was sued out existence... and oddly, I have both a FedPac service entrance and a Zinsco Magnetrip sub panel in my home. And replacing them both is on the near horizon (after tax day).
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Besides, everyone loves the smell of vinyl chloride in the morning. ;)
If memory serves, it wasn't until I was taking things down Sunday morning that I discovered I could not separate the cords-- that they'd melted together. Heh.
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If you're really concerned about it, you could mod the amp with a 15A power input fuse or circuit breaker. Then you could replace the cord end with a NEMA 5-15P. Then you wouldn't have to worry about overloading anything -- except for the 15A fuse, which is supposed to fail gracefully.
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If you're really concerned about it, you could mod the amp with a 15A power input fuse or circuit breaker. Then you could replace the cord end with a NEMA 5-15P. Then you wouldn't have to worry about overloading anything -- except for the 15A fuse, which is supposed to fail gracefully.
How would that help? Adding a fuse to the amp wiring does nothing to protect the unknown venue wiring (which is sized to the breaker size not the receptacle size - i.e. you can have 5-15R on #12 wire from a 20A breaker but you can't have a 5-20R on #14 wire on a 15A breaker), and only increases the voltage drop to the amp by the fuse's resistance.
The 5-15P ->5-20R adapter is fine unless you're trying to pass a UL inspection. It will have absolutely no measurable affect on amp performance, and as long as you build it with appropriate wire, will be safe. If there's a wiring overload, the [correctly sized for the wire] building OCPD will trip and protect the premise wiring; which is the whole point of the OCPD.
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The 5-15P ->5-20R adapter is fine unless you're trying to pass a UL inspection. It will have absolutely no measurable affect on amp performance, and as long as you build it with appropriate wire, will be safe.
You're right that there will be no measurable impact on performance, and if the building is wired correctly, the building OCPD will protect the circuit.
However, you're also assuming that the adapter is wired correctly. Putting a fuse in the amp could protect an incorrectly made adapter, and could protect a 59 cent 15A receptacle that may not be able to withstand a sustained 20A load (really 16A but that's another discussion). Although I'll admit it would be far easier and cheaper to just make the adapter correctly.