Spring reminder - think electrical safety

[evolvingpowercat]

Spring reminder - be safe and think electrical saftey when using 110 volt power with your Heartland camper.

A great web site for understanding risks of 110 volts and campers is:http://www.noshockzone.org

A good specific article there to read is: http://www.noshockzone.org/rv-electrical-safety-part-iv-–-hot-skin/

It talks about a simple device called a non-contact tester that can safely tell you if your trailer has any hazard.

 

[wdk450]

Re: Spring reminder - think electrical saftey

Be sure you know how to use the non-contact tester correctly. In this month's issue of HIGHWAYS (the Good Sam Magazine) in an article on maintaining your RV refrigerator, the well known RV expert author tells the reader to check with a non-contact tester BEFORE plugging in to park power. The non contact tester detects the radiated electrical field from an ENERGIZED cable (or RV chassis). If you test with the non-contact tester and don't have the RV plugged in to energized shore power (in the words of my esteemed former co-worker Rod Turner, KJ6NE) "That isn't a fair test".

 

[evolvingpowercat]

Re: Spring reminder - think electrical saftey

Agree, that there is a sequence to testing for problem power that Mike Sokol's article describes. It also describes the problem with non-contact testers, that you have to use them correctly or they will give a false negative reading and potentially give you a false sense of security. Mike Sokol's article says how to correctly use them:

Now, here are a couple of warnings about using non-contact testers to check for Hot-Skin conditions. 1) These testers need to have your hand wrapped around them to sense the earth ground; so if you hold them with just the tips of your fingers it’s possible to get a false-safe reading. 2) Non-contact testers need your feet to be near the ground to know the actual earth potential, so if you’re standing on a fiberglass ladder they won’t read properly. Additionally, since non-contact testers are looking for the voltage difference between the your hand and the plastic tip of the probe, if you’re standing inside an RV with a Hot Skin and you test your galley sink, they won’t indicate trouble when indeed there is. Therefore, always grip the non-contact tester firmly in your hand while standing on the ground outside your RV. And if your vehicle has as little as 40 volts of Hot Skin potential, the tester should alert you of the danger even without physically touching your RV. You can just slip your VoltAlert pen in your pocket and use it to quickly test any RV in the campground you might be visiting. It only takes a few seconds to test for a Hot-Skin problem this way, and you may save another RV owner’s life.

The article by Mike Sokol also emphasizes these tips:

[h=2]Quick Tips[/h]

• Do the Hot-Skin test after you’ve checked campsite outlet polarity and voltages with a volt meter.
• Perform a Hot-Skin test every time you plug into a new campsite or home power outlet.
• If you ever feel the slightest tingle or shock from your RV, avoid all contact, shut off the AC power at the pedestal, and get professional help to determine the cause of the shock.
• Even if you’ve stopped getting shocked from your RV because the ground is dry, the Hot-Skin problem has not fixed itself.
• Be sure to properly maintain your RV electrical system and test all RV interior outlets for proper polarity and grounding.

 

[jmsokol]

Re: Spring reminder - think electrical saftey

The article by Mike Sokol also emphasizes these tips:

Quick Tips

• Do the Hot-Skin test after you’ve checked campsite outlet polarity and voltages with a volt meter.
• Perform a Hot-Skin test every time you plug into a new campsite or home power outlet.
• If you ever feel the slightest tingle or shock from your RV, avoid all contact, shut off the AC power at the pedestal, and get professional help to determine the cause of the shock.
• Even if you’ve stopped getting shocked from your RV because the ground is dry, the Hot-Skin problem has not fixed itself.
• Be sure to properly maintain your RV electrical system and test all RV interior outlets for proper polarity and grounding.

Thanks for posting this. It's always good to review electrical safety procedures since it's very easy to get complacent around electricity. I have a new series of electrical safety articles I'm working on for the RV and Pro-Audio industry including something I call an RPBG (Reverse Polarity Bootleg Ground) outlet, and how they create a hot-skin condition that's not easily discovered by any standard metering test. But your Non-Contact Voltage Tester (NCVT) will find a RPBG outlet in a few seconds.

More on that later, but here's something I just posted on NoShockZone about electricians who get confused when wiring a 30-amp/120-volt outlet in your driveway, and accidentally wire it like a 30-amp/240-volt home dryer outlet. Of course, plugging your 120-volt RV into an outlet mis-wired with 240-volts will destroy most of your RV's electrical system in seconds. For details please read http://www.noshockzone.org/accidentally-plugging-into-240-volt-outlet/

Please pass this safety information on to everyone you know with an RV.

Thanks....

 

[brianharrison]

Re: Spring reminder - think electrical saftey

Sort of on topic wrt to the hot skin issue, but with a bit of a twist - I have a scenario that happened to me once. And since I have three of the esteemed electrical experts here thought I'd post to get your opinions.

I was pulling down the road, stopped under a 240KV transmission power line (just happened to be coincidental), went around to the trailer door and as I touched the trailer was shocked on my fingers with a sensation similar to touching a 9volt battery to your tongue. Shocked the sh*t out of me (figuratively). Unplugged the 7 way plug, still the same sensation. No shore power. Got back in - pulled 1000 yards down the road - no more "hot skin sensation".

Could only figure out it must have been differential in magnetic field/trailer/ground due to 240KV overhead transmission lines? Your thoughts?

Brian

 

[jmsokol]

Re: Spring reminder - think electrical saftey

I was pulling down the road, stopped under a 240KV transmission power line (just happened to be coincidental), went around to the trailer door and as I touched the trailer was shocked on my fingers with a sensation similar to touching a 9volt battery to your tongue. Shocked the sh*t out of me (figuratively). Unplugged the 7 way plug, still the same sensation. No shore power. Got back in - pulled 1000 yards down the road - no more "hot skin sensation".

Yes, I've actually experimented with this and discussed the topic with a few power companies. It's a well known fact among lineman that if they park their truck under high-tension lines that they need to jump clear of the truck when getting to the ground, or they'll get a good shock. Also, if you're laying irrigation pipe out in the mid-west under high tension lines, you're supposed to drive a ground rod and hook a temporary ground wire to the pipes when you're lifting them off the truck to avoid shock. And there are rules on place for farm machinery not to be over 14 ft tall if then can drive under these lines. The female engineer I talked to who ran the experiments said they parked 48 ft truck trailers under the lines and measured the discharge current. So line droop height was adjusted to be a minimum of 28 ft to maintain a 14 ft gap between the top of the trailer and the lines. This was the keep the induced current below 5 milliamps, which "shouldn't kill you" (her words). I asked about open circuit voltage, and she noted it could be enough to draw a spark. I then asked if a spark plug connected between the bumper of your RV and a ground rod would continuously spark, and said most likely it would under the proper circumstances. Yikes... That's probably around 10K volts and 5 mA current, which would feel like touching a lawn mower spark plug while running.

I have permission from my local power company to use a set of 500 kV lines for my own experiment, so now I just need a high-voltage meter that will go up to 50 kV or so for the experiment. If I do it this summer I'll be sure to take a video.

What got me interested in this was an email from a NoShockZone reader last year about getting shocked at a dump station that was located directly under high-tension power lines. He thought he was getting shocked from the water pipe, but he was really getting shocked from his RV and the water pipe was providing the ground.

Electricity is cool and interesting stuff, but you've got to keep your wits about you when playing with it. Here's the BPA article I was referring to: http://www.google.com/url?sa=t&rct=...sg=AFQjCNEz6i1jNrD36mJ4pZkIfLtKCFtFZw&cad=rja

 

[brianharrison]

Re: Spring reminder - think electrical saftey

Thanks Mike for the informative post. As usual I find the information you share to be very insightful and concisely stated. I will be curious to see your experimental video, and really - would love to be your right hand gopher while undertaking these type of experiments. These things are very cool to me.

We do not have any 500KV transmission lines up here where I live in the great white north, but there is a 500KV DC power line in the last stages of design and regulatory approvals. I would be interested if the 500KV AC and the 500KV DC transmission would create different induced currents. I will be adding noshockzone.org to my favorites. Thanks again.

Brian

 

[wdk450]

Re: Spring reminder - think electrical saftey

Brian:
I guess I am getting a little off the RVing subject matter, but I was surprised to learn about HVDC long distance power transmission. I was taught from early in my military electronics training that AC was better for this due to the ability to easily step up AC voltages with transformers, therefore minimizing I squared R heat losses through the cables. I did some reading on Wikipedia on the HVDC transmission systems and found that they can use LESS cable (1 phase cable instead of 3, and run half the circuit through the ground) and have less losses than AC transmission systems, due to no capacitance and skin effect losses on the DC systems. The large, elaborate grounding terminals on a West Coast system are awesome: See "Components" in:
http://en.wikipedia.org/wiki/Pacific_DC_Intertie
You learn something new every day!!! Edison finally wins out over Tesla/Westinghouse!

 

[brianharrison]

Re: Spring reminder - think electrical saftey

Wow - 1970 original in-service date. Thanks for the link.

 

[jmsokol]

Re: Spring reminder - think electrical saftey

Be sure you know how to use the non-contact tester correctly. In this month's issue of HIGHWAYS (the Good Sam Magazine) in an article on maintaining your RV refrigerator, the well known RV expert author tells the reader to check with a non-contact tester BEFORE plugging in to park power. The non contact tester detects the radiated electrical field from an ENERGIZED cable (or RV chassis). If you test with the non-contact tester and don't have the RV plugged in to energized shore power (in the words of my esteemed former co-worker Rod Turner, KJ6NE) "That isn't a fair test".

So I tracked down the author of this article, and he happens to be a good friend of mine and fellow RV expert Gary Bunzer. I think your reference to his article describing using a Fluke VoltAlert to test an unplugged RV is in error. That is, he was referring to two different procedures, not a specific testing order. Gary has been a powerful advocate of my proximity hot-skin test and I've appeared as a guest speaker during his workshops numerous times. So I know from personal experience that Gary knows EXACTLY how a Non-Contact Voltage Tester works, along with its limitations. And as a fellow author, I know how easy it is to be misread at times, which is why both Gary and I are very careful to check and recheck our work before it hits the presses. Unfortunately for us, most magazine and e-zine editors aren't in a position to double-check our technical logic, but will worry about punctuation and abbreviations until the cows come home. So please, if anything I write seems illogical, please ask me directly to check my logic. Could be as simple as missing a single word in a sentence which gives it a whole new (wrong) meaning. I take my writing very seriously, even for these short pieces in user forums. And Gary takes his writing very seriously, as well. Your feedback is always welcome, but please carefully re-read our articles in their entirety before challenging the facts.

 

[wdk450]

Re: Spring reminder - think electrical saftey

Mike:
Here is the paragraph I disputed copied from a .PDF of the refrigerator maintenance article in this month's Highways magazine. I e-mailed Highways about this safety error.

"A non-contact proximity tester is used before the coach is plugged
into shore power. It assures that the
RV and campground wiring is correct.
It can verify the polarity of any 120-volt
AC receptacle inside the RV. All RVers
should own one."

I would not doubt that Gary KNOWS how to use the tester, being the long-time RV professional that he is; just that someone slipped up on the sentence composition giving an unexperienced RVer reading the article a possible false electrical safety reading.

So I tracked down the author of this article, and he happens to be a good friend of mine and fellow RV expert Gary Bunzer. I think your reference to his article describing using a Fluke VoltAlert to test an unplugged RV is in error. That is, he was referring to two different procedures, not a specific testing order. Gary has been a powerful advocate of my proximity hot-skin test and I've appeared as a guest speaker during his workshops numerous times. So I know from personal experience that Gary knows EXACTLY how a Non-Contact Voltage Tester works, along with its limitations. And as a fellow author, I know how easy it is to be misread at times, which is why both Gary and I are very careful to check and recheck our work before it hits the presses. Unfortunately for us, most magazine and e-zine editors aren't in a position to double-check our technical logic, but will worry about punctuation and abbreviations until the cows come home. So please, if anything I write seems illogical, please ask me directly to check my logic. Could be as simple as missing a single word in a sentence which gives it a whole new (wrong) meaning. I take my writing very seriously, even for these short pieces in user forums. And Gary takes his writing very seriously, as well. Your feedback is always welcome, but please carefully re-read our articles in their entirety before challenging the facts.