... If you've had any interesting "shock" issues in the past or recently, please post them here. I'm trying for a grant that will allow me to make No~Shock~Zone a national electrical safety training program, so any examples you can provide will help with the process...
I hope that's true... but I keep getting arguments on other forums to the effect that "a little shock" is OK. Or there's only a hot-skin condition "when it's raining". I think that since many of you guys (and gals) are DIY types, you know the importance of understanding your subject matter BEFORE you dive in and start modifying systems. Any shock, no matter how small, is a sign that something is seriously wrong and should be investigated immediately.
It's amazing to me that buyers who have spent hundreds of thousands of dollars on new Class-A RVs are the most argumentative against testing campground power for proper grounding and voltage. They somehow think that spending big money "insulates" them from getting shocked, and I know that's simply NOT the case. The most expensive RV you can buy can be hot-skin electrified by plugging into a mis-wired outlet, and there's currently no Surge Protector or Voltage Protector on the market that will check for hot-skin voltages automatically and disconnect you from power. Such a device just doesn't exist.
Here's an article I just wrote about how electricians can get confused when hooking up a home 30-amp/120-volt RV outlet (TT-30) and sometimes mis-wire it with 240-volts. Because it "looks" like a 30-Amp/240-Volt Dryer outlet, they sometimes miss the note on the front of the outlet with a 125-Volt rating. http://www.noshockzone.org/accidentally ... lt-outlet/
I have a freind that bought a Surge Guard. If it gives him a green light eveything is good and he doesn't need to know any more. I'm trying to get him to read this.
Close, but not 100% true. I've confirmed with all the major "Surge/Voltage Protector" manufacturers that their surge protectors should stop 240-volts from getting into your RV in this type of mis-wiring scenario. However, some tech departments are predicting their surge protectors will be "smoked" by 240-volts, and die in the process of saving your RV's electrical system. Still a good choice since a Surge Guard is a lot cheaper than your RV electrical system, including appliances.
However, there are no surge protectors on the market (and I've confirmed this with all the major players) that will detect or protect you from an RV hot-skin condition caused by plugging into what I call a Reverse Polarity Bootleg Ground Outlet, or RPBG for short. This illegal connection results when an electrician wants to upgrade old, ungrounded wiring to include a grounded receptacle. By strapping the Ground screw to the Neutral screw, he makes a "bootleg" or "false" ground, which while in violation of the code, is not immediately dangerous. However, if the black (hot) and white (neutral) wires are swapped in the walls somewhere, now the Hot blade of the outlet is at 0 volts, while both the Neutral and Ground blades are at 120 volts. So anything you plug into this RPBG outlet with a grounded power cord will have its chassis electrified to a full 120 volts and 20 or 30 amps of current. The crazy thing is that your RV and/or appliances will all appear to operate normally in this state. The only way to know for sure is to use something like a Fluke VoltAlert to double check the outlet ground BEFORE plugging in, and checking the skin of the RV for hot-skin AFTER plugging in. See http://www.rvdoctor.com/2001/07/friends ... -mike.html for the original article which should be updated in a few weeks with this new information about Surge Protectors.
Here's my latest NoShockZone article about why a portable generator will sometimes "trip" a voltage protector telling you there's an open ground. It's all about the generator's Ground-Neutral internal bond (or lack of bonding). Included is a cheap ($2) way to build your own kludge plug to properly G-N bond Honda and Yamaha inverter generators. Please read http://www.noshockzone.org/generator-gr ... l-bonding/
Your moderator may want to post this along with my 240-volt miswiring article at the top of the page as a sticky.
That cottage had something like 2 or 3 add-ons, wich would explain the problem being limited to only one part of the building.
Yup.... It's almost impossible to wire a new building with an RPBG, simply because electricians are matching color-to-color on the wiring. And even if they accidentally swap the hot and neutral screws on the outlet, then a "reverse-polarity" outlet with a proper "ground" is still intrinsically safe. However, when you upgrade to a "grounded" outlet to an old "ungrounded" electrical system, that's when RPBG outlets are VERY possible. So if you see what looks like a brand new outlet in an old house, stage, dock, church, or campground, that's when you want to be suspicious and check the ground safety with a Non-Contact Voltage Tester.
I just got off the phone with my counterpart in the marine industry who told me there was a recent electrocution at a boat dock, and they discovered that some 200+ power pedestals on the dock did NOT have an actual ground wire but did have what looked like "grounded plugs". Closer inspection revealed the original electrician had simple jumped the neutral wire to the ground screw on the new "grounded" receptacles that made a bootleg ground, and that after the electrocution (which they blamed on the boat's wiring) they simply checked all the boat dock receptacles with a 3-light outlet tester and signed off as everything being safe. I'm betting the original electrocution was caused by an RPBG, and the inspectors don't know that a Reverse Polarity Bootleg Ground can even exist, nor are they aware that a 3-light tester can indicate the outlet is wired correctly, when it's actually wired as an RPBG with the ground and neutral contacts at 120-volts above earth potential. We're investigating this boat dock electrocution to try to prevent a future death.
It's so sad since many of these situations should have been obvious and would have been preventable with proper inspection. I'm working with the author of this article, Dave Rifken to develop simple testing methods for use around freshwater docks. Remember, any boat or dock with a power pedestal is a potential voltage gradient generator, so swimming within 50 to 100 feet of it could cause limb paralysis and drowning. And if you see someone in distress in the water near a freshwater dock with a hot-skin boat or conduit in the area, jumping in to save them could result in your own drowning. It's pretty scary...
I am curious about the answer,several contractors and such said the would do it the same way.
I would like to chat with you on the phone if possible,it's busy next week or so,let me know.
I am curious if I "spoke" correctly of if we are on 2 different sheets of music (I re-read my pm and it may be confusing)
Thankyou for your help,and the benefit others get from it
I have some time to talk on the phone this Friday for the following Monday. After that it's getting busy around here as I prep for final exams (I'm an adjunct professor).
But I've re-read your PM, and believe my evaluation of your grounding situation is correct. However, I could be reading something wrong in your text. We'll chat and I'll make sure to get my head wrapped around what you're talking about. But I would like to post whatever we figure out here on open forum since it could affect a lot of other bus builders.
I was just thinking about that old cottage again.... and that RPBG in the circuit that the washing machine was on, but almost right next to it was the dryer on a properly wired 240v circuit. If those two machines had ever touched and rubbed paint it could have led to a fire
You are correct. And look what happens when you have a sound system connected between two power outlets, one properly wired and the other with an RPBG.
As you can see from the diagram above, a microphone cable connected between the mixing board and the powered speaker will create a direct short-circuit between the two outlets. The cable will support the fault current, turning red hot and melting right before your eyes. Of course, this is very bad for the electronics and often does thousands of dollars in damage. Also, as I describe in this video below, you can't detect an RPBG outlet with a standard 3-light tester, metering between H-N, H-G, and N-G, or even with a $300 Ground Loop Impedance Tester.
RPBG outlets are not only dangerous to human life due to them creating a hot-skin condition, but will also damage and destroy electronics. As crazy as it seems, a single device plugged into an RPBG will appear to operate normally, but its chassis/skin will be electrified to a full 120 volts with 20 or 30 amps or fault current capability. Also, while RPBG outlets are difficult to create in new wiring, they're really easy to accidentally make when upgrading old outlets to include a "ground". And while any sort of bootleg ground (either reverse or correct polarity) is a violation of code, there has to be thousands or even millions of them around since it was a very quick and cheap way to upgraded outlets to be "grounded" back in the 60's and 70's.
. . .And finally, how many of you have felt any kind of tingle or shock from their "skoolie" or other RV?
Not a vehicle that I can remember, but our college radio station . . . .
40 years ago we first went on the air in the walk-out back basement of an old 1890s dorm. The used 10-watt Gates Radio (Harris) transmitter had a 20-foot ground lead connected through the window frame to a ground rod outside. The transmitter sat on a back countertop, and next to it was a small rack with the new modulation monitor and audio compressor/modulation limiter unit. They were both plugged into the same duplex receptacle box. I was the student Tech director, which meant I got the squawks from the air staff, fixed what I could, and called the First Class engineer on contract when needed.
One day, I had the transmitter unplugged, and put one hand on each cabinet. The unplugged transmitter bit me. I measured about 50 volts with an old-style analog meter between the outlet U-ground and the wire going out to the ground rod. When the transmitter was plugged in, the third prong and outside rod "sank" it all to zero. I don't believe it was a RPBG, I figured at the time it must have been an inductive or capacitive charge building up on the safety ground, as the bond was probably in the steam plant 4 buildings away, at the end of about 1/4 mile of wire. The live wires and floating ground were parallel all that distance. (In retrospect, the used tube-type EBS receiver in the audio rack may have had EMI capacitors on both the hot and the neutral to ground leaking the voltage, but I may have unplugged the rack during my tests.)
They were building a new student union/campus center at the time, and the radio station was moved in the next year or two after I left. The old dorm was torn down, and has been nothing but a lawn and memories for years. But that old wiring was an education not in the curriculum.
Someone said "Making good decisions comes from experience, experience comes from bad decisions." I say there are three kinds of people: those who learn from their mistakes, those who learn from the mistakes of others, and those who never learn.
One of the them had stopped breathing and was in cardiac arrest, but a quick thinking police officer called to the scene had a AED (Automated External Defibrillator) in his cruiser and was able to get his heart started. From what I've read it appears that everyone will recover (hopefully) but the oldest (2 was still listed in serious condition. This brings out two major points.
1) ALWAYS be aware of any overhead power lines when you're moving a ladder, goal post, vehicle or whatever. Most people are terrible at judging relative heights from the ground, so don't even get halfway close to any power lines. I think the rule is a 3-ft distance at the minimum from mid-voltage feeder lines, but even that's too close for me. I've had the fun of looking at autopsy photos of high voltage electrocutions back in my OSHA training days, so I stay WAY FAR away from any overhead lines. And be especially aware of any overhead lines if you're climbing on top of your "bus" for any reason. Power lines droop in the middle and it's surprising how close to the ground they can get. According to safety literature, you're supposed to maintain a 14-foot distance from high-tension power lines. Those are the big boys that can have up to 250,000 or even 500,000 volts and be at least 28 feet above the ground. So standing on top of a 13-foot tall RV can easily put you in the danger zone if you're parked right under high-tension lines.
2) Locate all AED devices in your church, campground, shopping mall, or place of business and commit them to memory. Every second is critical during an electrocution or heart attack. Most fire departments or EMS units will be glad to come by your place of business and do a short class on how they work as well as a demonstration of compression-only CPR. All modern AED's are quite smart and won't allow you to shock a healthy beating heart, so never hesitate to use one if you find someone unresponsive and you can't find a pulse. Just remember to call 911 first and get the EMS on the way.
You're most welcome.
Here's a recent article I wrote about watching out for "electricians" who mis-wire a TT-30 outlet with 240-volts instead of 120-volts http://www.noshockzone.org/accidentally ... lt-outlet/ and here's an article on how to make a special "kludge plug" that will bond the Neutral to the Ground bus in portable generators. http://www.noshockzone.org/generator-gr ... l-bonding/ A floating neutral in a portable generator will often cause RV voltage/surge protectors to improperly shut down when running from an external generator because it thinks you have an open ground. Please post these links to the top "sticky" post for everyone to read.