Members gadgetx23 Posted March 18, 2007 Members Share Posted March 18, 2007 Is there a simple way to determine if two outlets are on different circuits? We try to keep our lights and power amps on different circuits when possible, but we don't have a good way of knowing how the room is wired when we setup at new places. Last night we found out quickly. During soundcheck the breaker tripped on the two outlets that the power amps and lights were plugged into, but the guitar amps were still running; so we simple ran the lights to that circuit. Is there any easy way to figure this out in advance, short of flipping breakers to see what turns off? Link to comment Share on other sites More sharing options...
Members sharnrock Posted March 18, 2007 Members Share Posted March 18, 2007 There are things called tick tracers. Typically they're used on dead circuits, but I think they have ones that are good on live circuits too. You just hook up the the hot and neutral to the two leads coming off the transmitter. Then you go around with a little receiver wand thing, and if you put it next to a receptacle it'll give you a little sound and you know it's on the same circuit. If you don't hear a tone then it's on a different circuit. Link to comment Share on other sites More sharing options...
Members JohnnyGraphic Posted March 18, 2007 Members Share Posted March 18, 2007 My old band would trip the breakers on just about every gig! The drummer loved using lights and would plug in on the same circuit as the rest of the band-no matter how often we would try to get on a different circuit. Half of the way thru the gig, the stage would always go dark & silent. We'd go chase down the circuit breaker box, flip it and proceed. It was almost a guarantee that we'd be playing in the dark, just as much as we'd get feedback! Link to comment Share on other sites More sharing options...
Members Phil Clark Posted March 19, 2007 Members Share Posted March 19, 2007 With a volt meter measure between two hot leads on different outlets and if you get 220 instead of 110 you have two different circuits. An extension cord can help measure between two outlets that are several feet apart. Link to comment Share on other sites More sharing options...
Members burdizzos Posted March 19, 2007 Members Share Posted March 19, 2007 With a volt meter measure between two hot leads on different outlets and if you get 220 instead of 110 you have two different circuits. An extension cord can help measure between two outlets that are several feet apart. That will definitely work, but it's possible for two separate circuits to be on the same bus. Hell, 50% of the time, they will be. The probability of two adjacent circuits in a bar being on separate hot lines is very good since the breaker will probably be right next to each other in the panel. Since everything is tied together in the panel, except the two hots of course, there's no good way to test the circuits while hot. I just built two 50 foot extension cords using 12 gauge SJOOW cable, I'll just assume that outlets more than 50 feet apart are on separate circuits. I'm using LED lighitng, so it really doesn't matter. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted March 19, 2007 CMS Author Share Posted March 19, 2007 With a volt meter measure between two hot leads on different outlets and if you get 220 instead of 110 you have two different circuits. An extension cord can help measure between two outlets that are several feet apart. no... This method can only indicate that a pair of receptacles are on different circuits AND on different service phase legs. If the two circuits are on different breakers that are on the same phase leg, there is no voltage potential between 'hot' legs. It also has to assume correct wiring on both receptacles...if either has hot and neutral reversed, it'll appear to be on a different breaker. A circuit breaker indentifier such as this one found randomly via Google search:http://www.stayonline.com/detail.aspx?ID=2424 ..should make the job fairly easy. Link to comment Share on other sites More sharing options...
Members burdizzos Posted March 19, 2007 Members Share Posted March 19, 2007 A circuit breaker indentifier such as this one found randomly via Google search:http://www.stayonline.com/detail.aspx?ID=2424 Good call, I need to get one of those. Link to comment Share on other sites More sharing options...
Members agedhorse Posted March 19, 2007 Members Share Posted March 19, 2007 With a volt meter measure between two hot leads on different outlets and if you get 220 instead of 110 you have two different circuits. An extension cord can help measure between two outlets that are several feet apart. True, this means that you know you must have two seperate circuits because they reside on seperate phase legs. BUT, you can have seperate circuits that measure 0 volts between hot leads that reside on the same phase leg. The result of that reading is still an unknown. I use a clocked load, a 1 amp load switched at 1Hz repitition and use a clamp on ammeter to identify circuits. Not practical for working in clubs and bars with other people's power equipment as it requires the removal of panel covers and handling of potentially live conductors and connections. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted March 19, 2007 CMS Author Share Posted March 19, 2007 I use a clocked load, a 1 amp load switched at 1Hz repitition and use a clamp on ammeter to identify circuits. Not practical for working in clubs and bars with other people's power equipment as it requires the removal of panel covers and handling of potentially live conductors and connections. CBI's like the one I linked will work well, and all you need is the breaker panel door to be unlocked. No need to pull the cover. IMHO a good set of test gear for gigs is a $5 circuit tester, the $60 CBI, and a decent meter such as offered by Fluke. With this gear and the knowledge of how to use it (critical condition there), it should be possible to verify most venue power and wiring as reasonably safe. Link to comment Share on other sites More sharing options...
Members agedhorse Posted March 19, 2007 Members Share Posted March 19, 2007 I didn't see your post while posting! Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted March 19, 2007 CMS Author Share Posted March 19, 2007 I didn't see your post while posting! 'great minds' thinking alike??? Link to comment Share on other sites More sharing options...
Members agedhorse Posted March 19, 2007 Members Share Posted March 19, 2007 Yikes! Link to comment Share on other sites More sharing options...
Members Ear Abuser Posted March 19, 2007 Members Share Posted March 19, 2007 'great minds' thinking alike??? And yours do, too! Link to comment Share on other sites More sharing options...
Members Singin' Dave Posted March 20, 2007 Members Share Posted March 20, 2007 Hmmmm. This is a bit over my head. So, to execute the test as described by Craig above, you need to be able to access the breaker box, correct? Not sure this is an option at some of the dives I play. Any other tips? Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted March 20, 2007 CMS Author Share Posted March 20, 2007 And yours do, too! Hey, I resemble that remark! :D Link to comment Share on other sites More sharing options...
Members Phil Clark Posted March 20, 2007 Members Share Posted March 20, 2007 If you don't have access to the breaker box, then the best bet is probably the volt meter option. While it isn't accurate in all cases, it will work in a majority of instances, and is better than just guessing. You may also want to get an outlet tester that you plug in and it lights up and tells you if the outlet is grounded, and if the hot and neutral are reversed. Use that first, then test for separate circuits with the volt meter. Jerry has on occasion rewired outlets that were wired incorrectly, with the owners/managers permission of course. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted March 20, 2007 CMS Author Share Posted March 20, 2007 If you don't have access to the breaker box, then the best bet is probably the volt meter option. While it isn't accurate in all cases, it will work in a majority of instances, and is better than just guessing. Guessing would have exactly the same odds as using the volt meter...50/50. Link to comment Share on other sites More sharing options...
Members agedhorse Posted March 20, 2007 Members Share Posted March 20, 2007 Or 1 in 3 in the case of 3 phase. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted March 20, 2007 CMS Author Share Posted March 20, 2007 Or 1 in 3 in the case of 3 phase. :D Link to comment Share on other sites More sharing options...
Members gadgetx23 Posted March 20, 2007 Author Members Share Posted March 20, 2007 Thanks to all who responded. It's looking like there's not really a simple reliable way to do this without heading to the fusebox then, huh? I started carrying one of those little $5 outlet tester to check for ground and polarity after the guitar players complained enough about getting zapped from their mics BTW, off topic - can getting shocked from a mic because of a faulty ground damage the mic? Last Friday our guitar player did a show in a place with no ground available, so he was getting zapped all night. When I went to soundcheck his mic (Audix OM-2) on Saturday night, it sounded like he was singing through a pillow. The signal level was fine to the mixer, but sounded horrible. We had to switch out the mics and I didn't have a chance to go back and look at it. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted March 20, 2007 CMS Author Share Posted March 20, 2007 Thanks to all who responded. It's looking like there's not really a simple reliable way to do this without heading to the fusebox then, huh? I started carrying one of those little $5 outlet tester to check for ground and polarity after the guitar players complained enough about getting zapped from their mics BTW, off topic - can getting shocked from a mic because of a faulty ground damage the mic? Last Friday our guitar player did a show in a place with no ground available, so he was getting zapped all night. When I went to soundcheck his mic (Audix OM-2) on Saturday night, it sounded like he was singing through a pillow. The signal level was fine to the mixer, but sounded horrible. We had to switch out the mics and I didn't have a chance to go back and look at it. The fault would likely be at a device's AC ground, or lack thereof. Perhaps the ground lug is broken off a plug, perhaps the house wiring has no ground. This combined with another fault in whatever's plugged in that's allowing current to leak to the case of the device, and therefore, to dvices plugged into it, would allow that current to then find its way to ground via humans..... The leakage could damage the small wires inside a mic. Link to comment Share on other sites More sharing options...
Members gadgetx23 Posted March 20, 2007 Author Members Share Posted March 20, 2007 Right - there was simply no ground available in the place he played Friday night. But could this have damaged the mic and caused the problem I had with it the next night when we played (a regular show with ground)? Link to comment Share on other sites More sharing options...
Members gadgetx23 Posted March 20, 2007 Author Members Share Posted March 20, 2007 Sorry, didn't see the last line in your reply... Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted March 20, 2007 CMS Author Share Posted March 20, 2007 Right - there was simply no ground available in the place he played Friday night.But could this have damaged the mic and caused the problem I had with it the next night when we played (a regular show with ground)? It's not exclusively the lack of a ground that caused the problem, but a combination of a faulty device leaking current, and the lack of a ground path to clear it. The leaking current is using your buddy's body as a path to ground. A working grounding system would clear that fault current by providing the low-resistance path. If the leakage is high enough, it could trip a circuit breaker. It would almost certainly be high enough to trip a GFCI outlet. Just an FYI....GFI's do not need a working ground to function correctly. It's possible for such current to be high enough to damage a microphone, but what's much more important is that such current is dangerous. Get the gear used thoroughly checked by qualified technicians. Link to comment Share on other sites More sharing options...
Members Phil Clark Posted March 21, 2007 Members Share Posted March 21, 2007 Guessing would have exactly the same odds as using the volt meter...50/50. I have been using the volt meter test to find separate phases between wall outlets for all of the three years that I have been running sound, and while it may not be a perfect technique, we haven't yet had a problem with popping breakers or with the equipment shocking any of the bands we have mixed. So I would say that outlet testing for proper wiring and for 220 between hots is reliable in my experience. Particularly for people who don't have access to a panel, or even know where the panel may be. We do have a sniffer, and have used that too, when we have time and access to do that. Most reliable is when we get to set up our power tap, which Jerry does by temporarily installing our own breakers in the panel. He has enough different breakers that he is able to hook up to 90-95% of the panels out there. Link to comment Share on other sites More sharing options...
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