Members wesg Posted March 26, 2015 Members Share Posted March 26, 2015 Hey, All -- I bumped into what I believe is a serious electrical hazard last week. I had a Behringer RX1202FX rack mixer, connected to an APC rack PDU, connected to a stage power box with two NEMA 5-15Rs. I had an unbalanced instrument cable connected to the aux send in my hand, about to connect to a power speaker, when my arm touched the metal railing that surrounds the stage. I got a hell of a shock. Not full 120VAC, but a good lift nevertheless. My arm was dry. My equipment is in good condition. My assumption is that either the stage box or the railing are improperly grounded; maybe the stage box has a bootleg ground. This was before the show, so there was stuff plugged into the stage box, but nowhere near full load. Does my scenario support this? Do I need to do any checks to my equipment at home before raising this issue with the venue? I advised my band mates to stay the hell away from the railing, but I am not comfortable not doing anything further - if someone gets hurt, I will feel responsible. Any tips for corresponding with the venue? My band leader doesn't want to rock the boat, so I plan to send an anonymous letter. Should I have my lawyer do it? Should I just send it registered mail? What exactly should I tell them? Wes Link to comment Share on other sites More sharing options...
Members Shaster Posted March 26, 2015 Members Share Posted March 26, 2015 I am commenting only on the Behr RX1202fx. I owned one for a year or so and eventually discovered a rattling sound. Turns out there was literally a screw loose! This was one of two screws that secured the incoming AC power, so if the other one had let go, the potential for disaster could have been great. I am NOT suggesting this was in any way related to your experience, but based on what happened to me, I would at least look at your RX1202fx and make sure everything is fine. Actually there's no harm in giving all your gear the once over, perhaps visually and with a meter. Again I'm NOT saying your gear was the problem. Link to comment Share on other sites More sharing options...
Members StratGuy22 Posted March 27, 2015 Members Share Posted March 27, 2015 Stick one of those outlet testers in the stage box and see what happens. The APC unit didn't show a ground fault? Link to comment Share on other sites More sharing options...
Members agedhorse Posted March 27, 2015 Members Share Posted March 27, 2015 For certain, there was a hard potential difference between the railing and what was plugged into the outlet box (or the box itself). Could be that either the stage rail was touching something live and the outlet box was truely at ground or the other way around. If I was a betting guy, I would expect that the outlet box was not grounded and a live conductor inside the box was touching the box, electrifying your local equipment ground which you felt when you touched the grounded rail. Link to comment Share on other sites More sharing options...
Members wesg Posted March 27, 2015 Author Members Share Posted March 27, 2015 Thanks, All. I'm going to verify that the mixer's output and earth ground are connected together, and that there near-infinite resistance between neutral/hot and neutral/ground. I don't know for certain which IEC cord I used to plug it in, but I think it's safe to assume that all my cords are okay. They are all commercially made. Assuming everything checks out, I'm going to send the venue a letter. Andy's bet might also explain why the bass player had to "ground lift" his amp (newer Mark Bass unit), it was either humming or buzzing at FOH. Surprised I didn't have any issues with the keys. My XLR cables do not have pin one connected to the shield, and I am quite confident that Behringer does not transformer-isolate the output of the mixer. I guess pin one must be isolated from the chassis ground. Wes Link to comment Share on other sites More sharing options...
Members RoadRanger Posted March 27, 2015 Members Share Posted March 27, 2015 I'm going to verify [...] that there near-infinite resistance between [...] neutral/ground.Oh Vey, you really need to find someone that knows what they are doing before you kill yourself . Link to comment Share on other sites More sharing options...
Members wesg Posted March 27, 2015 Author Members Share Posted March 27, 2015 You are expecting neutral and ground to be tied together inside my equipment? I don't think so. The only place that should happen is where they are bonded at the building's main breaker panel. Wes Link to comment Share on other sites More sharing options...
Members Pro Sound Guy Posted March 28, 2015 Members Share Posted March 28, 2015 Get one of these and test what you plug your gear into. At least know if your outlet is wired correctly. http://www.techni-tool.com/462TE6151...150328022130:s Link to comment Share on other sites More sharing options...
Members wesg Posted March 28, 2015 Author Members Share Posted March 28, 2015 You know - I have one of those. I think I am going to plug it into my rack from now on, and just leave it there (assuming it fits). Wes Link to comment Share on other sites More sharing options...
Members Pro Sound Guy Posted March 28, 2015 Members Share Posted March 28, 2015 Plug it in to the wall to check first before you plug anything into that outlet. Link to comment Share on other sites More sharing options...
Members RiddimRider Posted March 28, 2015 Members Share Posted March 28, 2015 We played at a local bar one night and my PA head started acting weird and we were getting light shocks through the mics. I moved the PA to another outlet and all was well. Next time we played there , based on the advice of this group, I tested the outlet with an outlet checker and sure enough the ground had an issue. I taped over the outlet with masking tape and marked it as having a ground issue. Next time we played there, tape was missing but ground problem still existed. Link to comment Share on other sites More sharing options...
Members RoadRanger Posted March 28, 2015 Members Share Posted March 28, 2015 We played at a local bar one night and my PA head started acting weird and we were getting light shocks through the mics. I moved the PA to another outlet and all was well. Next time we played there , based on the advice of this group, I tested the outlet with an outlet checker and sure enough the ground had an issue. I taped over the outlet with masking tape and marked it as having a ground issue. Next time we played there, tape was missing but ground problem still existed. Welcome to the wonderful world of venues that don't give a **** about your safety. We could all boycott them but there are plenty of guys who don't give a **** about their own safety or the safety of their clients to take your place . Gotta be careful hereabouts too - many are "connected". I think most recent Governors of Rhode Island have gone to prison. We're lucky here in CT as it's a bit less than that LOL. Link to comment Share on other sites More sharing options...
Members wesg Posted March 29, 2015 Author Members Share Posted March 29, 2015 Light shocks through the mics, for me, means the gig stops NOW until I can verify the reason and implement a work-around. That is potentially a very big deal. People have died from that. Good call taping over the outlet. Too bad the venue didn't fix the problem. I spotted a taped-over outlet at another gig recently. I didn't even bother trying its mate. Wes Link to comment Share on other sites More sharing options...
Members Miko Man Posted March 31, 2015 Members Share Posted March 31, 2015 Get one of these and test what you plug your gear into. At least know if your outlet is wired correctly. http://www.techni-tool.com/462TE6151...150328022130:s I respectfully disagree that an outlet tester can (by itself) tell you that the wiring is correct. They do not detect a reverse polarity bootleg ground. If you also use a NCVT (non-contact voltage tester) and it doesn't light up when placed at/near the outlet, then you are very likely OK. Mark C. Link to comment Share on other sites More sharing options...
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