Plugged Power Amps Into 30 Amp Circuit And Sparks Stared Flying

B

Bill Garvin

Freshman
Nov 21, 2012
41
0
6
Lafayette, CA
Hey there! I accidentally plugged a couple of power amps into a 30 amp circuit, and when I turned on 1 power amp, sparks started coming out of the power amp after which the power amp stopped working. I turned on the other power amp and same thing happened. I then noticed the extension cord for the power amps was plugged into one of the pig tails which was connected to a 30 amp circuit at the spider. I did a check on the voltage off the 30 amp circuit and it was showing 124 volts. Was plugging into a 30 amp circuit what fried the power amps? I had no issues with any of my other equipment blowing up on the 20 amp circuits which also were reading 124 volts. Thanks!
 
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Re: Plugged Power Amps Into 30 Amp Circuit And Sparks Stared Flying

You measure too late and wrong. I have NEVER seen a spider box with a 125 volt, 30 amp outet. Every single one is 250 volts, except a couple of mine which were changed out to 125/250 volts L14-30 with an added neutral. When you measure hot to ground you will still see 125 volts but hot to hot will be 250 volts, or in your case ~248 volts. Whoever made the adapter screwed up. You then screwed up by using it. Then you screwed up a second time by turning another amp on after frying the first. They probably jammed an L5-20p into it and forced it so hard that it actually went in.

Hopefully you just toasted a couple fuses.
 
Re: Plugged Power Amps Into 30 Amp Circuit And Sparks Stared Flying

RYAN LOUDMUSIC JENKINS said:
You measure too late and wrong. I have NEVER seen a spider box with a 125 volt, 30 amp outet. Every single one is 250 volts, except a couple of mine which were changed out to 125/250 volts L14-30 with an added neutral. When you measure hot to ground you will still see 125 volts but hot to hot will be 250 volts, or in your case ~248 volts. Whoever made the adapter screwed up. You then screwed up by using it. Then you screwed up a second time by turning another amp on after frying the first. They probably jammed an L5-20p into it and forced it so hard that it actually went in.

Hopefully you just toasted a couple fuses.
Click to expand...

Thanks for replying. Definitely lots of screw ups on my part!
 
Re: Plugged Power Amps Into 30 Amp Circuit And Sparks Stared Flying

RYAN LOUDMUSIC JENKINS said:
You measure too late and wrong. I have NEVER seen a spider box with a 125 volt, 30 amp outet. Every single one is 250 volts, except a couple of mine which were changed out to 125/250 volts L14-30 with an added neutral. When you measure hot to ground you will still see 125 volts but hot to hot will be 250 volts, or in your case ~248 volts. Whoever made the adapter screwed up. You then screwed up by using it. Then you screwed up a second time by turning another amp on after frying the first. They probably jammed an L5-20p into it and forced it so hard that it actually went in.

Hopefully you just toasted a couple fuses.
Click to expand...

Nicely put! I would suspect there are lot more items cooked then just a fuse though, unfortunately.
 
Re: Plugged Power Amps Into 30 Amp Circuit And Sparks Stared Flying

How old were the amps? If they were newer you probably just blew the startup current limiter. The amps should be fine after replacing the parts. I had the same thing happen once on a mis labeled outlet.. Now I meter every outlet, no matter how many times I see it.

@ Ryan: I wan't there so I'm not sure but it sounds like he plugged into an L6-30, which is two hot legs and a ground. The amps saw 250 volts and hopefully blew the in-rush limiters.
 
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Hopefully you have better luck than me, bit last time I saw sparks fly out of an amp it was a pl-380 belching its guts after it was hit with 144v from a faulty generator. Ended up being a total loss on the amp.

Sent from my Galaxy Nexus 4
 
Re: Plugged Power Amps Into 30 Amp Circuit And Sparks Stared Flying

Kemper Watson said:
How old were the amps? If they were newer you probably just blew the startup current limiter. The amps should be fine after replacing the parts. I had the same thing happen once on a mis labeled outlet.. Now I meter every outlet, no matter how many times I see it.

@ Ryan: I wan't there so I'm not sure but it sounds like he plugged into an L6-30, which is two hot legs and a ground. The amps saw 250 volts and hopefully blew the in-rush limiters.
Click to expand...

I am betting it was an L5-20 to Edison adapter jammed into the 30 amp 250 volt recepticle. Yes, the spider box would have had a 250 volt outlet. Two hots and ground, no neutral.
 
Re: Plugged Power Amps Into 30 Amp Circuit And Sparks Stared Flying

What happened in my instance was an electrician had wired an L5-30 receptical as you would an L6-30. I had no idea. It was also PL 380. There was a loud pop, some smoke, and the amp went off. The in-rush device looks like the MOV's in power strips, right behind the switch. Replaced that and the amp was fine..Been three years ago

Edit: It's not that you plugged into a 30 amp circuit. I have a cheater (dryer) plug broken down into a four gang Edison box and use it often. It's that you plugged into a 250 volt 30 amp circuit
 
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Re: Plugged Power Amps Into 30 Amp Circuit And Sparks Stared Flying

RYAN LOUDMUSIC JENKINS said:
You measure too late and wrong. I have NEVER seen a spider box with a 125 volt, 30 amp outet. Every single one is 250 volts, except a couple of mine which were changed out to 125/250 volts L14-30 with an added neutral. When you measure hot to ground you will still see 125 volts but hot to hot will be 250 volts, or in your case ~248 volts. Whoever made the adapter screwed up. You then screwed up by using it. Then you screwed up a second time by turning another amp on after frying the first. They probably jammed an L5-20p into it and forced it so hard that it actually went in.

Hopefully you just toasted a couple fuses.
Click to expand...

Ryan, I think you probably nailed it EXCEPT I don't believe it would be possible to cross mate different NEMA style connectors no matter how hard someone pushed. I suspect one of them was miswired. To the OP, can you confirm that the mated connector and receptacle were matching NEMA numbers? Just for my own peace of mind.
 
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Re: Plugged Power Amps Into 30 Amp Circuit And Sparks Stared Flying

Kemper Watson said:
Edit: It's not that you plugged into a 30 amp circuit. I have a cheater (dryer) plug broken down into a four gang Edison box and use it often. It's that you plugged into a 250 volt 30 amp circuit
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Kemper,

Your cheater plug can be wired so each 120 volt outlet is receiving the proper voltage, but 30 or 50 amp dryer plugs are protected by 30 or 50 amp circuit breakers.
If your four gang Edison box does not also include 15/20 amp breakers, the outlets or 15/20 amp plugs could be overloaded and melt down. Definitely a fire hazard, and illegal for good reason.

Art
 
Re: Plugged Power Amps Into 30 Amp Circuit And Sparks Stared Flying

As someone who doesn't know enough about electrical engineering... if you don't know what you're plugging into, you're almost certain to end up with doom on the evening's menu. Case and point.
 
Max Warasila said:
As someone who doesn't know enough about electrical engineering... if you don't know what you're plugging into, you're almost certain to end up with doom on the evening's menu. Case and point.
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This is also why the best designed system that doesn't follow accepted professional practices probably isn't a good idea.
 
Re: Plugged Power Amps Into 30 Amp Circuit And Sparks Stared Flying

I'll jump in and add to this, always remember to meter between ALL pins. Not just a voltage test between a single phase and an earth. This will assist in detecting things like reversed phase/neutral. The two phase and earth variant of outlet you guys have in the states seems to be a common point of errors. A simple meter to earth kinda looks like the power you're hoping for. +1 to use a meter instead of a second amp!
 
Re: Plugged Power Amps Into 30 Amp Circuit And Sparks Stared Flying

Kemper Watson said:
How old were the amps? If they were newer you probably just blew the startup current limiter. The amps should be fine after replacing the parts. I had the same thing happen once on a mis labeled outlet.. Now I meter every outlet, no matter how many times I see it.

@ Ryan: I wan't there so I'm not sure but it sounds like he plugged into an L6-30, which is two hot legs and a ground. The amps saw 250 volts and hopefully blew the in-rush limiters.
Click to expand...

Hi Kemper, and thanks for the reply! Not sure how old the amps are, as they were a rental. They are (that is hopefully are and not were) PL 2's, so hopefully they had some kind of protection from dumbos like me!
 
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Re: Plugged Power Amps Into 30 Amp Circuit And Sparks Stared Flying

Charles Harrigan said:
Hopefully you have better luck than me, bit last time I saw sparks fly out of an amp it was a pl-380 belching its guts after it was hit with 144v from a faulty generator. Ended up being a total loss on the amp.

Sent from my Galaxy Nexus 4
Click to expand...

Thanks for the reply. Sorry to hear about that, and I have my fingers crossed.
 
Re: Plugged Power Amps Into 30 Amp Circuit And Sparks Stared Flying

RYAN LOUDMUSIC JENKINS said:
I am betting it was an L5-20 to Edison adapter jammed into the 30 amp 250 volt recepticle. Yes, the spider box would have had a 250 volt outlet. Two hots and ground, no neutral.
Click to expand...

Ryan, you are right. I checked the spider yesterday, and one plug was labeled 30 amps, 250 volts. Just curious why they have a 30 amp 250 volt plug on the spider. Do people like to run clothes dryers while they are at the gig? :D~:-D~:grin:
 
Re: Plugged Power Amps Into 30 Amp Circuit And Sparks Stared Flying

Kemper Watson said:
What happened in my instance was an electrician had wired an L5-30 receptical as you would an L6-30. I had no idea. It was also PL 380. There was a loud pop, some smoke, and the amp went off. The in-rush device looks like the MOV's in power strips, right behind the switch. Replaced that and the amp was fine..Been three years ago

Edit: It's not that you plugged into a 30 amp circuit. I have a cheater (dryer) plug broken down into a four gang Edison box and use it often. It's that you plugged into a 250 volt 30 amp circuit
Click to expand...

Thanks Kemper! I now understand what all the sparks were about. :blush:
 
Re: Plugged Power Amps Into 30 Amp Circuit And Sparks Stared Flying

Bill Garvin said:
Ryan, you are right. I checked the spider yesterday, and one plug was labeled 30 amps, 250 volts. Just curious why they have a 30 amp 250 volt plug on the spider. Do people like to run clothes dryers while they are at the gig? :D~:-D~:grin:
Click to expand...

Spider boxes are common in temporary power distribution. Think about the places and circumstances where temporary power is used, and sound reinforcement probably doesn't hit 1%. Construction is probably the largest segment. Portable arc welders are one possible user of the 240v/30 amp service. Floor cleaning machines, cooking (catering) appliances, office trailer, RV...

Think outside our little industry and you'll develop a list of potential users of that service.
 
Re: Plugged Power Amps Into 30 Amp Circuit And Sparks Stared Flying

Steve Payne said:
Ryan, I think you probably nailed it EXCEPT I don't believe it would be possible to cross mate different NEMA style connectors no matter how hard someone pushed. I suspect one of them was miswired. To the OP, can you confirm that the mated connector and receptacle were matching NEMA numbers? Just for my own peace of mind.
Click to expand...

Thanks for the reply! I'm ashamed to say before now I didn't know what Nema numberrs meant, so I can't confirm this. According to the link below, it looks like a female L6-30R would be a bigger receptacle than a female L5-20R, and have a different spacing on the lugs, or am I mistaken on this? I don't recall having any problem plugging the male 20 amp, 125 volt pigtail into the female 30 amp 250 volt receptacle at the spider. Should I be able to plug a male L5-20R pigtail into a female L6-30R receptacle at the spider? I'm definitely confused!!!!

NEMA Plug and Receptacle Configurations
 
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