3 weekends in a row, EMS tripped each time

[myredracer]

Installed a PI EMS unit (30 amps) in our 2014 TT when we bought it. Last time it tripped was 3 seasons ago. On each of the 3 last weekend outings the EMS has tripped! Twice on open ground and once on reverse polarity.

One of the pedestals also had a defective breaker and in that case the maintenance guy replaced the complete front on the pedestal with an old one from their "stock" of old ones from another nearby CG. The other CG had just completed a major electrical upgrade so they got all the old pedestals.

This past weekend was an odd one. Their maintenance guy recognized me from the previous weekend trip and didn't even ask me why I thought there was a problem. He installed a brand new 30 amp receptacle and a "new" old breaker that was allegedly in good shape. Every time he turned the breaker on, after about 10 seconds there was a faint puff/buzz sound and power went out in our TT. Breaker handle didn't trip. He pulled things apart 5 or 6 times to check and same thing happened each time. It made no sense and kept doing even after redoing and tightening connections. No evidence of carbon tracking.
I've never heard of that happening before. He said he thought it might have been due to the blades on our 30 amp plug (Marinco) being slightly too short but that makes no sense either. Each time power was lost there was no load from our TT except for the converter and each time it took about the same 10 seconds to lose power. Maybe it was a bad breaker?

Then we plugged our 30 amp cord into the 20 amp recept. with an adapter and it worked fine so we spent the weekend running on 20 amps without issue. The "interesting" part was when the maintenance guy went to put the lower cover back on the pedestal and shorted it to one of the live 150 amp lugs and sent sparks a-flying.

All I can say is I sure am glad we have an EMS. Open grounds and reverse polarity are potentially dangerous and even lethal. If you haven't got one, go order one today because you just never know...

FWIW, CGs are something else when it comes to electrical. I've seen so many pedestals and panels in CGs that are in frightening condition and even some exposed wires that should even be condemned in some cases. Then you've got non-licensed untrained people doing electrical work that just don't know what they're doing.

[road-runner]

Optimistic Paranoid wrote:

I can see both sides of this issue, so won't get into an argument over it.

That's the best approach. Let people know the pros and cons, then they can decide which risk they'd rather be exposed to. The fear of spoiled food is why (I assume) that the NEC has had a GFCI exemption for outlets powering refrigeration devices. This exemption, however, has been watered down in the last few NEC versions. For example, there's no longer a GFCI exemption for refrigerators in garages and unfinished basements. It wouldn't surprise me if new campground outlets are required to be GFCI protected in the not-too-distant future.

As a data point, in the house I've had 2 refrigerators and one freezer continuously running on GFCI protected circuits for about 10 years with no trips, and when the motorhome is plugged in at home it's on a GFCI, and has never caused a trip. And yes, when I'm gone for an extended amount of time I occasionally worry if the fridges and freezer at home are still running, balanced against wanting an early warning in case one of them does develop a power leakage to its outer shell.

[Optimistic_Para]

DrewE wrote:
My fridge would just switch to propane.

I can see both sides of this issue, so won't get into an argument over it. I will note that more and more people seem to be switching to non-propane, regular household fridges, and even have separate freezers in their basements.

Me, I'll just make it a a point to use a non-contact voltage tester whenever I plug in.

[DrewE]

Optimistic Paranoid wrote:

DrewE wrote:
To be honest, I don't entirely understand why RV receptacles aren't required by the NEC to have GFCI protection.

I can think of several reasons why it wouldn't be a good idea.

Your motor home is plugged in to 50 or 30 amp service that has GFCI built in. You leave for the day in your toad and return late that evening to discover that the GFCI tripped shortly after you left, and your rig has been without power all day.

All the food in your refrigerator and/or freezer is now warm.

Your dinner, which was left in a slow cooker, is not only not cooked, but it's probably spoiled.

You left the A/C on because you left your dog/cat(s) in the motor home and rather than being safely cooled all day, they've been locked in an oven.

We wouldn't want our sticks & bricks to be on a master GFCI, we want the option of having some circuits, like to our furnace and our freezers to be on non-gfci circuits. The same logic applies to our mobile homes.

My fridge would just switch to propane. A lost meal is a small price to pay for electric safety, in my opinion. Pets are a reasonable concern for some people in some areas; presumably in those areas, one ought to have some other backup system in place in case of an ordinary power outage from whatever cause. (Most of the places where I camp, towards the northeast, the interior of the RV would not get too hot for a pet without air conditioning provided there was fresh water available and some ventilation. I rarely use the air conditioner myself. I do of course understand that e.g. Arizona is entirely different!)

If the GFCI trips, there is (most likely) an electric fault with the RV, and quite often one that is potentially dangerous. I could see having somewhat relaxed trip current requirements for RVs since it's reasonable to expect more leakage current. More than one RV is around with a fridge or water heater element that leaks current to ground, and the owners know nothing about it.

[Optimistic_Para]

DrewE wrote:
To be honest, I don't entirely understand why RV receptacles aren't required by the NEC to have GFCI protection.

I can think of several reasons why it wouldn't be a good idea.

Your motor home is plugged in to 50 or 30 amp service that has GFCI built in. You leave for the day in your toad and return late that evening to discover that the GFCI tripped shortly after you left, and your rig has been without power all day.

All the food in your refrigerator and/or freezer is now warm.

Your dinner, which was left in a slow cooker, is not only not cooked, but it's probably spoiled.

You left the A/C on because you left your dog/cat(s) in the motor home and rather than being safely cooled all day, they've been locked in an oven.

We wouldn't want our sticks & bricks to be on a master GFCI, we want the option of having some circuits, like to our furnace and our freezers to be on non-gfci circuits. The same logic applies to our mobile homes.

[BFL13]

I checked out the info on hot skin, thanks. That info was all about shore power and pedestals.

I am now wondering about any danger when on inverter whole house with shore power plugged into the inverter (converter off) I still have my Surge Guard in the shore cord line when on inverter. I have it on the bitter end of the shore cord where it goes to the AC panel instead of using it out at the plug end (had to swap around the surge guard ends, but it still works the same.)

A variation on that--what about if the shore cord plug going into the inverter's receptacle has no ground prong ? (30/15 adapter and ground prong missing, eg) (The cord's ground wire is still grounded to the frame by the Main breaker, but---)

This is one of the explanations and he also has some videos.

https://rvtravel.com/proper-rv-chassis-grounding-to-prevent-hot-skin-condition/

[Optimistic_Para]

I didn't know the Surgeguard had a built in GFCI. Certainly any surge protector that DOESN'T have a GFCI built in will provide no protection from a hot skin condition.

[DrewE]

Optimistic Paranoid wrote:
Neither your Surgeguard, nor any of the testers you are using, will protect you from the kind of dangerous mis-wiring that will electrify the metal parts of your RV, called a 'hot skin condition'.

Go to YouTube, search on 'hot skin condition' and you will find several good videos explaining how this happens and how you can test for this potentially deadly - as in 'can kill you' - situation.

The SurgeGuard would generally protect from danger in a hot skin since it has a GFCI built into it. Any leakage from the hot skin to ground would trip it--and it ought to trip immediately if the ground lead were continuous through to the surge guard unit, even absent any leakage current. The others which lack a GFCI would not detect this condition.

Certainly a hot skin condition is very dangerous and should not be ignored (and is well worth checking for). To be honest, I don't entirely understand why RV receptacles aren't required by the NEC to have GFCI protection.

[Optimistic_Para]

Neither your Surgeguard, nor any of the testers you are using, will protect you from the kind of dangerous mis-wiring that will electrify the metal parts of your RV, called a 'hot skin condition'.

Go to YouTube, search on 'hot skin condition' and you will find several good videos explaining how this happens and how you can test for this potentially deadly - as in 'can kill you' - situation.

[BFL13]

Thanks for the good info. I am not sure what exactly my particular SurgeGuard will do, but it has tripped at times, so I know it does something.

My routine before plugging in to any 120v pedestal is to first try out my three-light tester (with 30/15 adapter), so that should take care of any "issues" the surge guard does not.

If there is low voltage suspected, I stick my voltmeter in set to 120v.

So unless I missed something, I think I can continue with that routine, and not have to buy an actual EMS like the OP has. (That will also keep me from having to make up a funny bonded adapter when using my Honda gen, based on other threads about that)

[wa8yxm]

I was prepared to talk about older parkes Increased heat (outside) and thus increased air conditioner load.. But .. Not your problem

Rather what you found was DECREASED maintenance (reverse polarity, open ground) these things are actually DANGEROUS in fact both of 'em together is life threatening.. Are you not glad you got that EMS?

[DrewE]

BFL13 wrote:
Would a "surge guard" have saved the RV in those same situations? mine (Model 44740RV RV30)also has "Shockshield", which is a sort of GFCI near as I can tell from the (vague) instructions.

What does an EMS do that a surge guard doesn't?

You're correct that Shockshield is a GFCI; there's also a couple of MOVs providing (rather limited) voltage surge protection. There are various models of SurgeGuard units which provide varying additional protections, and the higher end ones would cover the same sorts of things that these other EMS units provide.

Briefly, they disconnect when the input voltage is too high or too low, or when they detect a miswired outlet (swapped hot and neutral or unbonded ground). Most if not all PI EMS units do not provide ground fault protection for the RV. They do also have a few MOVs for (again rather limited) voltage surge protection. I think the PI EMS units also disconnect for wildly incorrect line frequency, but the chances of encountering that are pretty much nonexistent (their allowed range is something like +/- 10 Hz, while the electric grid is regulated much much more closely--around +/- 1 Hz short term and much more accurately over the course of days or weeks so electric clocks stay correct). Finally, these units usually have a turn on delay mainly to prevent restarting an air conditioner against a full pressure head in the event of a brief power interruption.

The low voltage, high voltage, and miswired socket protections are probably the most valuable, in my opinion. High voltage generally is a result of miswiring somewhere, commonly a poor or broken neutral connection at some point.

[Optimistic_Para]

An EMS also monitors the voltage level and will shut off if it either goes too high or too low.

In a packed campground, if everybody's air conditioners are running full blast, it's not unusual to see the voltage drop to below 105 volts. This can damage equipment, as can voltages above 128 volts, which is not high enough for a surge guard to notice and deal with.

High voltages are much rarer than low voltages, but can happen under some circumstances. I once measured 142 volts on an outlet powering some equipment I was trying to troubleshoot on my job, before I retired.

[BFL13]

Would a "surge guard" have saved the RV in those same situations? mine (Model 44740RV RV30)also has "Shockshield", which is a sort of GFCI near as I can tell from the (vague) instructions.

What does an EMS do that a surge guard doesn't?

[MrWizard]

it saved your RV

I think i would have used a different subject line

"three weekends in a row, EMS saved my RV"