Pedestal issue or remove the surge protector

[dgerfan]

Summary:

I have a delicate issue that I'm hoping for wise advice in dealing with. I've been work camping at a park since Jan 2022 and from Winter thru early Spring we haven't encountered any issues with park power. However once it started to warm up in late Spring to now when everyday is over 100 we are experiencing a couple power events weekly. Suffice it to say the Owner of the Park has troubleshooted the issue multiple times. One time he tightened all the connections and cleaned off the ground another time he replaced the breakers and one other time he did something in an upstream panel (don't have the details on what was actually done).

Now when I report issues to him he says it's my surge protector and that I should remove it. I normally just tell him I"m not comfortable removing it but now I think he's starting to get frustrated. Today he asked that I find another RV'er in the park to temporarily switch Surge Protectors with. Well this park mostly only has weekend folks or individuals that stay for a couple days so it's hard to get to know someone let alone ask them if we could switch SPs temporarily. What makes matters worse is we are in the only full hookups site so moving to another site is out of the question.

Details:

2020 Grand Design 31MB: Only has one A/C so technically we can run off 30A and if we utilize more than 30A our Victron Inverter can pull from our batteries.
Surge Protector is a Surge Guard* 50A – Model 34951 and per its documentation it protects against the following conditions:

Power surges
Open ground
Open neutral – line and load side
Elevated ground line current
Low (<102V) and high (>136V) voltage
Overheating receptacle
Reverse polarity
Miswired pedestal
High neutral current (50A model)
Low and high frequency protection

I'm not an electrician however I assume that one of the "protects against conditions" is occurring at the pedestal and the surge protector is doing its job by cutting off power. And on a couple occasions I was even able to see on the SP's lcd screen that one of the legs was below the low voltage shutoff threshold. But mostly the "condition" is resolved and nothing is displayed on the lcd screen. The thing I don't understand is that when the SP restores power only one leg is restored. I assume its because the other leg is still showing the low voltage condition however when I go out to look the lcd screen it shows both legs above the threshold. What gives?

Really I'm just looking for some practical next troubleshooting steps to present to the Owner that could possibly put him closer to finding the issue. I really appreciate my job here (installing wifi) and don't want to jeopardize it in anyway. Also we are only here for one more month before heading over to the National Rally.

Any help is much appreciated. Please see attached homemade wiring diagram that I made after installing solar.

Thanks!

[ncitro]

dgerfan You don't say but I'm assuming you're on a 30A site? If so then in your dog bone adapter both hot legs (L1&L2) are combined and should read the same voltage. Not familiar with the Surge Guard, but my Progressive EMS shows both the current error as well as the last error received which is helpful for tracking low voltage. Usually what happens is your AC comes on, loads down the line and the voltage drops. Then the EMS kicks off (104V for mine) and shuts everything off. Then since the heavy load is gone the EMS turns back on and clears the error since the voltage is back up. I was actually just fighting this exact issue with a similar inverter setup with WondersAwait. If the campground isn't cooperative to resolve it there's a few tricks you can try. First drop your power assist current level in the inverter. If you've got solar to keep the batteries charged, drop it down to some amount that causes it to go into assist. Maybe tell it your shore power is 10A or so. This will cause it to draw part of it's load from the inverter and not load down the shore line as heavy.

Another option would be to order a new EMS from Amazon (assuming you can get a delivery somewhere). They've got a good return policy, see if that's the issue (it's probably not) and return it when it does not fix it and see what the owner will do.

If it's a 50A site, see what the voltage is on both lines. If one is higher than the other, move your AC breaker in the main panel (if you're comfortable with that), and see if the problem goes away. The other line may not drop as much voltage.

See you at the rally!

[ncitro]

dgerfan

Also I'd recommend this upgrade (assuming you're running Victron gear). I did this after staying in a campground with a low voltage issue and it was a big help with keeping track of where my line was since my EMS display was in my wet bay.

https://gdrvowners.com/forum/operati...-venus-ui-mods

[howson]

dgerfan and ncitro --- timely thread. I experienced the exact same symptoms yesterday afternoon. The hard-wired EMS displayed error code PE6 (Line 2 Voltage Low (Line voltage below 104 volts).

L2 powers the living room air conditioner and water heater (the latter was off). L1 powers the rest of the camper including the bedroom air conditioner (which was also running). L1's voltage level was fine--stayed north of 110v. It was only L2 that dropped below the 104v threshold even though the power draw was nearly equal on each leg.

The Victron Multiplus is set to 50A (available shore power) so it was not assisting in any way that I know of--it should have been in passthru mode.

Only other item of note is yesterday was the warmest since we've been in this park (near Eau Claire, WI) and the park has the most campers since we've arrived (typical Friday inflow of weekend campers).

I know the Multiplus does not manipulate voltage (like the Hughes Autoformer), all it does is react (via it's Transfer Switch) to low voltage depending on the settings under the GRID tab.

Since I wasn't sure what mine was set at I checked--right now it's 104. That's too low, since it is exactly the same as the EMS. Changing the low voltage setting to 106V should force the Multiplus into Inverter mode before shore power cuts off. As Neil suggested, the other "trick" is to set the shore power maximum input current to some setting less than maximum so the Multiplus goes into PowerAssist mode before shore power cuts off.

Below is a snip from the Grid settings showing the present configuration of my Multiplus--going to change the Low Voltage cutoff to 106V.



Howard

[howson]

ncitro -- what I don't understand is how 1/2 of a 120V split phase line (hope that's the right term--is it actually dual phase?) can be lower than the other half. With the neutral shared, why aren't both voltages dragged down an equal amount? Can't quite wrap my head around L1 being <104V and L2 being >110V.

If it's a circuit breaker problem (high resistance) as you suggested...that's easy to reconcile, but if the breaker is OK then what's the cause?

Scott'n'Wendy ? Jkwilson?

[ncitro]

ncitro -- what I don't understand is how 1/2 of a 120V split phase line (hope that's the right term--is it actually dual phase?) can be lower than the other half. With the neutral shared, why aren't both voltages dragged down an equal amount? Can't quite wrap my head around L1 being <104V and L2 being >110V.

If it's a circuit breaker problem (high resistance) as you suggested...that's easy to reconcile, but if the breaker is OK then what's the cause?

Scott'n'Wendy ? Jkwilson?

I see this a lot in campgrounds. The 30A plug in your pedestal is shared with one of the legs. Your pedestal is tied to some number of other sites before going to a main breaker somewhere upstream. If the other sites on your main are either using their 30A outlets, or only that line on the split phase (one AC or not balanced) then that line is going to sag more.

That's fine for the shared neutral, it does not care about the voltage as long as the one way current does not exceed 50A (the rating of the wire) the breaker on the pedestal should trip before that happens.

[Country Campers]

The closest one to the power feed, main circuit breaker, wins all of the power. I have seen this in a campground one time where we had lots of power but the 8 sites after us, especially the last one, had varying power. The last one actually fried their AC and microwave as the voltage was so low, they did not have any EMS.

I would also think that there may be an issue with the main power supply to the campground you are hosting at. It may be off of a circuit that is at or close to the end of the line or the transformers feeding the campground are not in the best shape. The problem arising in the heat of summer causes me to think of the main power grid.

Brian

[TedS]

What you are seeing is an unbalanced three-wire power system. More power(current) is being drawn on one leg than the other causing more voltage drop in that leg. Too many 30-amp loads are on one leg. The system would need to be better balanced; connect some 30-amp feeds to the lesser loaded leg.

[trkester]

What you are seeing is an unbalanced three-wire power system. More power(current) is being drawn on one leg than the other causing more voltage drop in that leg. Too many 30-amp loads are on one leg. The system would need to be better balanced; connect some 30-amp feeds to the lesser loaded leg.

So I'm guessing it's easy to get too many 30-amp loads on one leg if the park has 50-amp pedestal's and many folks use 30-amp dogbones that draw off one leg of the 50? An assumption is dog bone manufacturers don't randomly alternate which leg of the 50 to combine for the 30 plugs.



Terry

[ncitro]

So I'm guessing it's easy to get too many 30-amp loads on one leg if the park has 50-amp pedestal's and many folks use 30-amp dogbones that draw off one leg of the 50? An assumption is dog bone manufacturers don't randomly alternate which leg of the 50 to combine for the 30 plugs.



Terry

Yes that's right. That said most campgrounds (not all) that have 50 amp pedestals have 30A outlets so no dog bone would be needed. When they wire the park they're "supposed to" stagger the 30A outlets onto different phases to try and balance the load.

[TedS]

I was assuming the pedestal has three outlets. A 50-amp, a 30-amp and a 20-amp. If there is no 30-amp a dogbone may used to drop a 50-amp to a 30-amp outlet. I don't think the dogbone manufacturer pays attention as to which leg, L1 or L2, is used. So you could have lots of dogbone adapters on L1, for instance, causing the excess voltage drop.

[ncitro]

Yes I've only seen one park ever that had 50A only outlets. Was a high end motorhome park my parents were staying in. Pretty much every other 50A pedestal I've seen has a 30 and 20A outlet in it.

[Jkwilson]

ncitro -- what I don't understand is how 1/2 of a 120V split phase line (hope that's the right term--is it actually dual phase?) can be lower than the other half. With the neutral shared, why aren't both voltages dragged down an equal amount? Can't quite wrap my head around L1 being <104V and L2 being >110V.

If it's a circuit breaker problem (high resistance) as you suggested...that's easy to reconcile, but if the breaker is OK then what's the cause?

Scott'n'Wendy ? Jkwilson?

A couple scenarios.

First, the split phase only exists on the user side of the transformer, and there will be multiple transformers at most parks. Every site on the same transformer shares the same 240 legs and neutral. A loose connection or undersized wire on a hot leg can result in low voltage on that leg when it is loaded. The transformer is still 240 between the hot legs, but there can be voltage drop in the wire.

A bad connection in the neutral can cause the neutral voltage to change relative to the line voltage when the legs are loaded differently. You’ll still have 240V between the legs, but the line to neutral voltage may be 100 and 140 or any other pair of voltages adding up to 240. This can happen for all users on the transformer if the bad neutral is there, or within your RV if the bad neutral is there.

If the utility service is inadequate at the park, you may see L-N voltage on both legs near 130V with light load, but dropping substantially when loaded. This is because they’ve tapped higher voltage outputs on the transformer to help compensate for lower voltage from the utility, but it can only help so much.

[TedS]

Another point, the neutral line will be carrying more net current. The neutral line carries near zero net current in a balanced system load. The neutral line could overheat if the net current is too high for the wire size. The voltage loss on the neutral line will also subtract from the hot line voltage.

[TedS]

Just to add another scenario. If most 50-amp trailers have their primary or only air conditioner wired to L1, then that adds more unbalanced to all 30-amp outlets on L1, for instance.