By Mike Sokol
Hey Mike,
I’ve recently purchased the top Progressive EMS 30 Amp surge protector which seems to work great. I now have several extra test gadgets (the Fluke Non-Contact Voltage Detector, as a example) and wonder if I need to hold on to them. Can I now just plug into pedestal power and not worry about extra electrical testing? Thanks. —Martin F.
Dear Martin,
That’s a great question. To answer it we need to determine if there are any dangerous voltage conditions that can’t be detected by an EMS or “smart” surge protector. If not, then you’re home free and don’t need any additional tests. However, if there are undetectable conditions, then additional test gear and procedures would be indicated.
I’ve been studying ways that electrical outlets can be miswired or fail for nearly half a century, and while EMS “smart” surge protectors can detect and disconnect you from many of these power failures, I can tell you unequivocally that there are at least three conditions I know of that can’t be corrected by any smart/EMS surge protector on the market. Here’s my list: –
Downstream loss of ground: If you’re using an in-line surge protector that mounts on the pedestal itself, it’s still possible to develop a hot-skin voltage on your RV if your shore power plug develops an open ground where it bonds to your RV. This could be from a loose or broken ground wire where it bonds to your RV chassis. According to my readers, sometimes it’s in the shore power cord itself, while in at least several instances it was in the power inlet connector on the side of the RV. And a bunch of times it was due to a loose chassis bonding screw in the RV’s power center panel. I believe the last one was simply due to road vibration.
Reflected Hot Skin: If the campground pedestals develop a loose or broken ground wire as it feeds back to the campground’s incoming service panel, then several RVs in a “loop” can have their chassis connected together but not actually grounded. So a short in the wiring of one of these RVs can “reflect” a hot-skin voltage back to the other RVs in the line.
While smart surge protectors can detect this condition and shut down your incoming AC power, they can’t disconnect your RV from this now “hot” ground. So your power will go off, but the skin of your RV will still be “hot.” Again, I’ve had a few dozen NSZ readers contact me about strange readings in a campground which I diagnosed and named as a Reflected Hot-Skin Condition. So I know this happens.
RPBG (Reverse Polarity Bootleg Ground): This is perhaps the most dangerous miswiring condition of all, and one that I discovered and named for the electrical industry.
A Reverse Polarity Bootleg Ground can be created by an outlet that’s been intentionally wired with a false ground-to-neutral bond instead of running a separate ground wire as required by code. Since ground wires weren’t required by code until the late 1960s, there are millions of outlets in the U.S. without a real EGC (Equipment Grounding Conductor). While many of them have been properly upgraded with a new ground wire, back in the ’70s (and even now) some lazy electricians didn’t do it correctly and just made a “bootleg ground” with a jumper wire between the neutral and ground screw on the outlet.
This is a code violation for a lot of good reasons. If there’s also an accidental polarity reversal in the same outlet with a bootleg ground, then the chassis will be energized with a full 120 volts. Currently there is no smart surge protector or 3-light tester on the market that can either detect this condition or disconnect you from it. And the really dangerous thing is that an RPBG condition will seem to be safe. All the appliances in your RV will work properly, and there will be no surge protector alarms. However, the skin of your RV will now be directly connected to the incoming 120-volt hot wire.
I’ve personally seen this miswiring condition dozens of times, and have tons of emails from readers that I’ve diagnosed with this condition from the pro-sound, home construction and RV industries. However, an RPBG can easily be discovered in a few seconds with a Non Contact Voltage Tester (NCVT).
That’s why I think that using an NCVT like a Fluke VoltAlert is still a great extra test, no matter what type of EMS or smart surge protector you’re also using. It only takes a few seconds to confirm that you don’t have a hot-skin voltage on your RV. If it does detect a hot skin, then you’ve been warned before you or a loved one are shocked or electrocuted. And as you’ve seen me do this numerous times in my videos and at RV industry seminars, a hot-skin test with an NCVT only takes a few seconds to perform.
So while a smart surge protector largely eliminates the need for you to actually “meter” the campground pedestal before plugging into shore power, I believe you should still add an NCVT hot-skin test to catch any other possible dangerous wiring conditions that might otherwise go undetected.
Let’s play safe out there….
Mike Sokol
Mike Sokol is an electrical and professional sound expert with 40 years in the industry. Visit NoShockZone.org for more electrical safety tips. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.
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A related issue should caution people as well. In my communications industry job before I retired I encountered several houses where people had some appliances with a reverse polarity issue- where there was either an old non-polarized outlet with an equally old device plugged in reverse (hot blade to neutral -slot receptacle). This would result in everything that was plugged in on that electrical service to become “hot.” What a shock! Other times it was the neutral blade trimmed to fit either way into the outlet. We always trained our people to use their supplied foreign voltage detectors, but some did not.