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[Tim McCulloch]

Exactly right. How many times have you fired up a big genny on an outside gig, and the first thing you do is check the one voltage and frequency. Why? Because we don't trust generators.

I trust generators but I don't trust the last asshat that rented it and decided to compensate for voltage drop over his too-small cable by setting the output voltage at 146v.  (yes, I've found that).  We see things like that when a genset has been on a construction site, out in the oil patch or used for temporary building power.

That said, we've developed a good relationship with a primary generator shop in our area.  We tell them we need a unit that is "computer-friendly, event-quality."  We tend to get units with <1000 hours, and have crystal controlled frequency and the voltage is spot on when they deliver it.

And I still check line freq, output voltage and neutral bonding before the genny tech leaves the site.

[Mike Sokol]

And I still check line freq, output voltage and neutral bonding before the genny tech leaves the site.

Everyone... please post pictures of any incorrectly wired power outlets you find.

Thanks...

[Jordan Wolf]

Everyone... please post pictures of any incorrectly wired power outlets you find.

I'll take a look around the hotel...

[Jonathan Johnson]

Everyone... please post pictures of any incorrectly wired power outlets you find.

Thanks...

I wish I had a picture of the wiring in my grandpa's barn, before I rewired it. Talk about a rat's nest of wires! Carefully tracing the wires, I discovered that one outlet had no means of cutout except pulling the meter or cutting the wire. No fuses, no circuit breakers.

It seems his body did not conduct electricity well. He would work on the electric fence (>1000 volts) without shutting it off; he said he could feel a little tingle. 120V didn't faze him in the least.

It was after he died (natural causes, not electrocution) that I educated myself on proper wiring methods and rewired both the barn and the house.

Below are two junction boxes I recently removed from my church. Their condition is exactly as they were prior to removal. They had no covers, were fed by non-grounded circuits, no wire nuts (twist & tape), and the few knockouts that had clamps had loose clamps. These were located in the crawl space, inconveniently right above the most convenient place to crawl. It was a nerve-wracking experience to scrape one's back on these.

I do not believe these were installed by my grandpa, but by another member of the church who has passed on. (There is still some rewiring that needs to be done to ensure proper grounding at all outlets and to more evenly distribute loads, but I think we've got the most dangerous stuff remedied.)

The point is there is a lot of bad wiring out there. You can test the outlets and they may test OK, but you don't know what's hiding inside the walls. Connections like these can be a fire hazard at currents below the rating of the fuse or circuit breaker.

[Mike Sokol]

The point is there is a lot of bad wiring out there. You can test the outlets and they may test OK, but you don't know what's hiding inside the walls. Connections like these can be a fire hazard at currents below the rating of the fuse or circuit breaker.

I think that churches are some of the worst offenders in terms of dangerous wiring. They're often on very limited budgets, use untrained volunteers to do renovations, and add way more sound, video and lighting than was ever intended for the original wiring.

For instance, I taught a seminar in an old church in New Jersey a few years back. My contact there said I was going to be in the "new" addition that was done in '95.... Oh, that's 1895! Someone had run zip cord inside the walls and poked it out of fist-sized holes with a combination of unboxed power outlets and Edison bulb sockets with plug adapters. Yikes...! I was running long extension cords to the next room trying to get grounded power that wouldn't kill me.

Another church's gym had what appeared to be a brand new, grounded outlet installed on the wall behind the projector screen. Seemed like a good place to plug in my demonstration rack... but as soon as I did I saw the voltage bar on my Furman power strip was "pegged" to the red. I didn't power up the rack and then metered the outlet, which turned out to be their "special outlet" for the floor buffer which needed 240 volts. That's right, a standard NEMA 5-15 outlet designed for 120 volts with 240 volts wired into it. Fortunately I didn't turn on the full rack, but unfortunately I had cheated a bit and had a Sennheiser RF receiver plugged into a power strip which fed the Furman. Of course, I burned up the RF receiver but saved the rest of the rack from electrical damage. I'm a lot more careful around "new" outlets now. 

I could go on and on, but the point is to never assume that the outlet wiring is correct. I generally don't have these power problems on big gigs where we bring our own distro. It's those simple little gigs where we just need to throw up a few speakers on sticks and run a mic or two that get us into trouble. 

[Kemper Watson]

I've run into 220 on an Edison outlet before. Outside a hotel on a guest pavilion. Custodian finally admitted that there was a marker glued to the brick wall that "must have fallen off".

[Mike Sokol]

I've run into 220 on an Edison outlet before. Outside a hotel on a guest pavilion. Custodian finally admitted that there was a marker glued to the brick wall that "must have fallen off".

An Edison NEMA 5-15 or 5-20 outlet can NEVER be legally wired to 240 volts, no matter how big the signage.

There's a really quick way to test for 240 volt wiring using a non-contact tester such as a Volt-Alert. If there's interest here I'll make a video of it and post.

[Jonathan Johnson]

Below are two junction boxes I recently removed from my church. Their condition is exactly as they were prior to removal. They had no covers, were fed by non-grounded circuits, no wire nuts (twist & tape), and the few knockouts that had clamps had loose clamps.

You'll notice that one box has a conduit fitting. This box actually was attached to conduit. But the conduit was on the load side... the line feeding this box was an old ungrounded 2-wire Romex. Somebody "grounded" it by running a copper wire from the conduit setscrew to a cold water pipe. The wire was wrapped around the cold water pipe, not clamped on. As for the cold water pipe, it was never bonded to the ground conductor at the service entrance, and a recent underground water line replacement had left about 16" of metal pipe buried... under the church where the soil was bone dry.

Did I mention ALL of the receptacles at the church have a grounding slot?

[Mike Sokol]

Did I mention ALL of the receptacles at the church have a grounding slot?

All I can say is WOW!

I've seen similar "grounding" some 30 years in an old apartment kitchen from the 1950's. There were new "grounded" outlets all around the sink, powering the refrigerator, etc... but when I used a Ground Loop Impedance Tester (GLIT), which shoots a single-cycle 20-amp pulse down the ground, we heard a big "zap" under the sink and the test failed. I could see a spark under the sink every time I hit the test button on the GLIT. 

Investigation showed that all of the kitchen outlet grounds were tied to a single loop of wire twisted around the copper cold water pipe under the sink. Of course, there was copper oxide in the way and it was a loose contact, but it was good enough for a 3-light tester to say the outlets were OK. The landlord accused me of burning up his wires with my fancy tester, so we ran a new wire down to the basement and bonded it in the service panel ground, and all was well. But after that I wondered about every "ground" in the apartment building. 

Of course that high-z "ground" would not have been able to sustain enough current to trip the circuit breaker (or blow the fuse in an old house). If it was a GFCI outlet it could have protected you from shock by tripping itself. But there wasn't a GFCI in sight, and wouldn't be required by code for many years.

As a side note, do you think this thread should be also posted on the Church Sound Forums? There's nearly 400,000 churches in the USA alone, and I've got to wonder just how many of them have dangerous wiring.... 

[Mike Sokol]

For those of you who are morbidly curious, here's a picture of my NoShockZone test bench that I bring along on NSZ and ASSIST seminars. Note there's a B&K AC power supply in the left with lets me bias the chassis of any audio gear up to 120 volts AC, a Glo-Melt soldering transformer which allows me to insert up to 3 volts and 40 amperes of ground-loop differential between any two pieces of audio gear, plus a lot of ammeters, voltmeters, non-contact testers and audio isolation transformers.

Kids... don't try this at home! 

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