Important - check this every time you set up |
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wingnut2312
Senior Member Joined: 25 Aug 2013 Location: MI Online Status: Offline Posts: 231 |
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Topic: Important - check this every time you set up Posted: 22 May 2014 at 8:08am |
Ok, so since the could potentially kill someone, I'm going to ask a very 4th grader ish question. The Non contact pens, are you to stand barefoot or shoed outside with your hand firmly wrapped around the pen? If so, do you touch it to the step or just any solid metal part?
Great info and article, but I wish they would just have a section that says "if you are half retard, do this". I would happily admit to being half retarded and go thetre. |
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2014 rpod 182G
Ford Expedition |
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Camper Bob
podders Helping podders - pHp Joined: 26 Sep 2011 Location: Portland Oregon Online Status: Offline Posts: 913 |
Post Options Quote Reply Posted: 22 May 2014 at 8:45am |
Wow. That's quite a story. Glad no one was hurt. Thanks for the heads up. Safe Travels.
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Camper Bob and Camper Sue
Gracie the Wonder Dog (12 LB. Mini Dachshund) 2013 Rpod 171HRE(ORPod) 2016 Lance 1685 2015 Nissan Pathfinder |
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jmsokol
Groupie Joined: 21 May 2014 Location: Maryland Online Status: Offline Posts: 89 |
Post Options Quote Reply Posted: 22 May 2014 at 9:24am |
Actually, here's a video of me doing a hot-skin test with a Fluke VoltAlert. http://www.youtube.com/watch?v=Y8h64X33aKg Yes, you stand on the ground near your RV after plugging into the pedestal and turning on the circuit breaker, but don't touch the RV with your hand first. You do need to have your hand wrapped around the voltage pen/tester to establish the earth reference but any grip will do. These NCVT pens are all plastic and rated to safely touch up to 1,000 Volts AC without passing any current to the person doing the test, so you don't have to worry about getting shocked if you do touch an energized surface. All modern RVs have every major metal piece bonded to the chassis, so you can pick anything convenient for this test. The wheels or hitch are great places to test, as are the metal steps and the metal door frame. Note that these testers work from a distance depending on voltage, so if your RV is hot-skin energized to 120-volts it will beep and light up from more than a foot away, sometimes up to 2 feet. If it's energized to 80 volts it will beep from maybe 6 to 8 inches away, and 40 volts will cause it to beep once you touch the surface with the tester plastic tip. There's no need to dig through paint or rust like you would with a voltmeter probe. Since your tow vehicle is attached to the RV via the metal hitch, it will also have the same hot-skin voltage as your RV. So if your RV is hot-skin electrified and still hooked to your tow vehicle, you can get a shock while opening your car door. With any voltage tester it's important to establish that the unit itself is working before you do the test. That's why I prefer the style of Non Contact Voltage Tester that requires you turn it on, then has a blinking light showing that the battery isn't dead. Many of the newest testers are "always on" which appears to be convenient. But you won't know if the batteries died while hanging out in your tool box and it could fail to indicate an energized surface. So it's best to poke your tester into the pedestal outlet first to establish that it's still working before you do your hot-skin test. Please let me know if you have any more questions. |
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mike@noshockzone.org
www.noshockzone.org |
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wingnut2312
Senior Member Joined: 25 Aug 2013 Location: MI Online Status: Offline Posts: 231 |
Post Options Quote Reply Posted: 22 May 2014 at 9:38am |
YES!!! See, that's a proper "half retard" explanation, lol. Thank you!!
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2014 rpod 182G
Ford Expedition |
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Camper Bob
podders Helping podders - pHp Joined: 26 Sep 2011 Location: Portland Oregon Online Status: Offline Posts: 913 |
Post Options Quote Reply Posted: 22 May 2014 at 10:48am |
I'm constantly amazed at the level of technical expertise there is on this forum. Keep up the good work. Your advice makes us all safer and makes our Pods more useful and fun. Thank you all who participate here whether asking or answering questions. It makes all of our camping experiences safer and more fun. Safe Travels.
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Camper Bob and Camper Sue
Gracie the Wonder Dog (12 LB. Mini Dachshund) 2013 Rpod 171HRE(ORPod) 2016 Lance 1685 2015 Nissan Pathfinder |
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jan demarinis
Groupie Joined: 22 Apr 2014 Location: Northern CA Online Status: Offline Posts: 54 |
Post Options Quote Reply Posted: 22 May 2014 at 10:56am |
I agree! Thank you all.
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techntrek
Admin Group - pHp Joined: 29 Jul 2009 Location: MD Online Status: Offline Posts: 9062 |
Post Options Quote Reply Posted: 22 May 2014 at 1:46pm |
Something I didn't make clear in my first post, if any camper (or an appliance, or the shell of the power pedestal at a campground) tests positive it means 2 things. Problem one, there is a fault somewhere which has electrified the exterior metal. Problem two, the ground ("equipment grounding conductor") is not connected properly so it isn't doing its job to prevent problem one from killing you. So if the tester gives you a positive reading you have 2 problems to fix. Unplug the camper immediately without touching it, or the power pedestal, only the cord.
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Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ Pod instruction manual
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wingnut2312
Senior Member Joined: 25 Aug 2013 Location: MI Online Status: Offline Posts: 231 |
Post Options Quote Reply Posted: 22 May 2014 at 1:58pm |
So don't touch it with my tongue to see if it sticks or not?
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2014 rpod 182G
Ford Expedition |
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techntrek
Admin Group - pHp Joined: 29 Jul 2009 Location: MD Online Status: Offline Posts: 9062 |
Post Options Quote Reply Posted: 22 May 2014 at 2:00pm |
Only try that in very cold weather, after the camper is unplugged.
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Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ Pod instruction manual
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jmsokol
Groupie Joined: 21 May 2014 Location: Maryland Online Status: Offline Posts: 89 |
Post Options Quote Reply Posted: 22 May 2014 at 7:08pm |
Just a few clarifications. First of all, while you might think there needs to be an internal hot-to-ground fault to produce the voltage in the first place, that's not entirely true. ANY appliance plugged into a power plug can have some current leakage that will produce a voltage of some level. But the AMOUNT of fault current is limited by UL Labs to less than 0.75 mA for an "ungrounded appliance" such as your iPhone charger, or less than 3.5 mA for a "grounded appliance" for something like your microwave oven. Generally, anything plugged into an electrical outlet and NOT malfunctioning will have its chassis migrate to around 1/2 of line voltage. So it's perfectly normal (but somewhat scary) to measure 60 volts AC on the body of your iPhone while plugged into its wall-wart charger. But because the maximum leakage current is supposed to be under 0.75 mA, that's right below the current threshold that most people will notice a shock. On the other hand, a microwave oven (or any other grounded appliance) can leak up to 3.5 mA of fault current and still be considered "safe" by UL standards. This will generally produce the same 60 volts on the chassis if left ungrounded, but that 3.5 mA of current at 60 volts will produce a very noticeable, but not dangerous shock. And all these leakage currents are additive, so if your RV has a broken ground wire (EGC - Equipment Grounding Conductor) then everything plugged into your RV can leak more current to the chassis, and it's entirely possible to have 20 or 30 mA of leakage fault current available even if nothing is really "wrong". I call this a low-current (high impedance) fault, which can be painful but generally not deadly. Now, if your EGC is in place, then that 20 or 30 mA of current will be drained harmlessly to the grounding point of your service panel. However, if there's no ground path in your power cord and you touch anything metal on your RV while standing on damp ground or grass, then you can feel a very big shock. Now remember that 10 mA is a pretty good shock, and 20 mA will cause your hand to clamp down on a wire or ladder rung and not be able to let go, and 30 mA through your chest cavity for a few seconds almost guarantees heart fibrillation and death in minutes if CPR isn't immediately begun, so even these "low current" leakage voltages can get dangerous. The second type of ground fault is a high-current (low impedance) short from a hot wire to the chassis inside an appliance or your RV's electrical system. This often happens when a screw is driven through a wire in the wall, or the insulation of a wire has worn through from road vibration, or a cable was pinched in an access door, etc... This type of high-current fault can reach circuit breaker amperage level, making 20 amps (or more) of current available at 120-volts. Without a low-resistance ground connection back to the electrical service panel, touching your RV is equivalent to sticking your finger in the light socket while standing in your bathtub full of water. Since a human body has somewhere around 1,000 ohms resistance with wet hands/feet, that 120-volts will produce upwards of 100 mA of fault current through your body, which is WAY above safe limits. So unless you're pulled off the energized chassis within a few seconds and CPR started within a few minutes, you're dead from electrocution. Now, this hot-skin test isn't something you need to do every time you walk up to your RV, but I would certainly test every pedestal receptacle ground for improper voltage BEFORE plugging in your RV power cord. Then do a quick check on the chassis/skin of your RV with a NCVT such as a Fluke VoltAlert or Klein NCV-1 to make sure your extension cord ground is good. If there's a voltage on your RV skin/chassis while plugged in, then immediately turn off the pedestal circuit breaker, unplug your shore power connection, and contact the campground manager. After your initial test while making camp, you should only have to pull our your NCVT if you feel ANY kind of shock from your RV while still in camp at the same location. And the same goes for when you visit any of your RVing buddies at their campsites. If you feel ANY tingle at all while touching their RV, then pull out your trusty NCVT and do a hot-skin test for them. If it beeps and lights up, then they have a hot-skin condition of at least 40 volts, which could be a low-current leakage condition (shocks but doesn't kill you) or a high-current leakage condition (deadly under all damp conditions). But for sure they have lost their ground connection and need to power down and unplug immediately. You will NEVER read more than a few volts above earth potential on the skin/chassis of a properly grounded RV. If you do measure more than a few volts, then your ground is broken for some reason. Why doesn't your GFCI protect you from these situations. That's another story, but remember there's no GFCI required on a 30-amp TT-30 outlet, it's only required on the 20-amp outlet at the pedestal. |
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mike@noshockzone.org
www.noshockzone.org |
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