Low voltage campground.

Cavie

Senior Member
Location
SW Florida
Long Post. Hi guys. I haven't been here much since I retired in 2016. I figured 50 years was enough. I have a question I can't figure out or understand what is going on. Might be long bit I'll try to keep it simple.

I spend my summers in a seasonal campground in Western MA. The park has a 6 year old DIY wiring system. All new wires, Peds, meters etc. However, the wiring is very much undersized Alm direct burial cable.. It's unbelievable the distance they traveled to feed 48 campsites with too small of wire and no transformers. But that's a different story. Fact is I have very low voltage.

I use a Federal Pacific buck/boost transformer. I boost about 15 volts. Most RV'ers use a Hughes "Autoformer" that boost 10 % of what ever voltage is present. .I have a 30 amp 120 service. Plugged into a 30 amp single phase pedestal. L1-30 amp receptical. L2- 20 amp gfi recp.
This is where it starts to go sideways. All the peds are fed with a 50 amp 2 pole breaker from a distribution panel 1/2 way thru the park.

Non-boosted volt voltage changes all the time ( by the Minuit ) depending on the park load. This is Monday morning 6 am so the voltage is up pretty good.
At My ped I have a non-loaded voltage of L-1 = 122 volts. L-2 = 124. I can deal with that. I boost the 122 to 138 (remember I said it changes). I'm using this am's present #'s. L2 is at 122 unboosted. I just boost L-1.

Here is my problem. I am running a 13 amp A/C load. Nothing else on.

Park voltage boosted add A/C add Mr. Coffee add toaster
L-1 122 138 122 114 106.
L-2 124 128 131 133

I have 2 plug in volt meters inside the RV. L-2 is on a separate extension cord direct to the ped GFI 20 amp outlet. Not feed thru the RV. I can read both of them as I turn on the switches.

Why the hell does L-2 go up when the load is added to L-1??? The owner will not let me investigate because his buddy electrician installed everything and it's all go by him. Think Hillbillies. Yes, I am socially incorrect and proud of it.

Thanks for lstening.
 

retirede

Senior Member
Location
Illinois
There is a bad neutral connection somewhere.
Your line to line only drops from 246 to 239.
If it deteriorates further, you could start frying stuff!
 

GoldDigger

Moderator
Staff member
The symptom is crystal clear. If both hots and the neutral were of equal impedance, then 1/2 of the circuit voltage drop would be on the neutral return.
So 122/124 should go to, for example, 114/128, with the neutral offset of 4 volts contributing half of the 8 volt reduction in L1-N voltage and increasing L2-N voltage.
You are instead seeing 122/124 --> 114/133 with the neutral offset being 9 volts and the reduction in L1-N voltage being only 8 volts. Allowing for small measurement error, this tells you that almost all of the circuit resistance is in the neutral.
Short of correcting the wiring, your best recourse is to avoid the dependence on the neutral by using a 240/120 transformer fed from L1-L2 as your 120V supply.
It is not clear that retirede's 239V figure is correct since you seem to be missing the last L2-N voltage in your table.
And you are already seeing an offset of the neutral voltage just from the magnetizing current in your boost transformer before you add actual loads.
 

retirede

Senior Member
Location
Illinois
It is not clear that retirede's 239V figure is correct since you seem to be missing the last L2-N voltage in your table.
And you are already seeing an offset of the neutral voltage just from the magnetizing current in your boost transformer before you add actual loads.
You’re right - I just looked at the last 2 numbers as a pair.
I should not post before coffee!
 

Cavie

Senior Member
Location
SW Florida
A little edit is in order. There is no boost on L2. Move the 128 131 133 over one spot. I figured it was a bad neutral. I'll never get to owner to understand that. I may just have to move.
 
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GoldDigger

Moderator
Staff member
They might still be a pair if there was no L2-N value for attaching the boost transformer. Unless you use the CODE format multiple spaces are compressed to a single space so tables do not work right.

Like this:
Code:
L-1 122 138 122 114 106
L-2 124     128 131 133
 

GoldDigger

Moderator
Staff member
With that correction it now looks like a normal VD situation with equal resistance in the hot lead and the neutral. For the last entry neutral offset is 9 volts and the difference in L1-N is 16V, approximately twice the neutral offset, as it should be with equal resistances.
 

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
With that correction it now looks like a normal VD situation with equal resistance in the hot lead and the neutral. For the last entry neutral offset is 9 volts and the difference in L1-N is 16V, approximately twice the neutral offset, as it should be with equal resistances.
If I understand this correctly the L1-N at the output of the buck/boost transformer changed by 138 - 106 = 32V from unloaded to max load. And as you mentioned the neutral drop represents 9V of this because L2-N changed by 9V even though it was not loaded. Therefore the drop on L1 after the booster is 32V - 9V = 23V. This would be 23V x (122/138) = 20.3V before the booster, or more than 2X the drop on the neutral.
The impedance of the buck/boost may be contributing to this drop. If so then one rated at a higher kVA rating may help as long as it isn't so big the magnetizing current becomes significant.

If practical in the OP's situation, perhaps the primary of the buck/boost could be run as an isolated winding (i.e., not with an auto-transformer connection) off of L2-N instead of L1-N. This should reduce the voltage drop a little because any increase in L2-N voltage with loading will increase the boost on L1 instead of reducing it. Also (138 - 122) / 122 = 0.13 or 13% of the L1 input current is off loaded to L2, and the current drawn by the buck/boost primary subtracts from the load current on the neutral instead of adding to it. The isolated winding connection to L2 and N should allow it to be plugged into the existing GFCI, unless it's already marginal.
This would not give a big improvement, but maybe a 25% reduction in the L1-N voltage drop at the buck/boost input.
 
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hillbilly1

Senior Member
Location
Atlanta,Ga
What I have found in campgrounds, is the majority of the load is on L1, and L2 gets the leftovers from the 50 amp TT and coaches. Every other pedestal needs L1 and L2 swapped, either on the input of the loadcenter, or the breaker feeding the 30 amp receptacle moved to L2. This will help tremendously when the campground is full. This will also help people that have the 50 amp shore power and surge protectors. Some models of surge protectors will trip out of the voltage imbalance is severe.
 

Cavie

Senior Member
Location
SW Florida
They might still be a pair if there was no L2-N value for attaching the boost transformer. Unless you use the CODE format multiple spaces are compressed to a single space so tables do not work right.

Like this:
Code:
L-1 122 138 122 114 106
L-2 124     128 131 133
[/QUOT
 

Cavie

Senior Member
Location
SW Florida
Yes digger, that is correct. I can not get it to display like that. 6 pm this afternoon with the A/C, mr coffee, toaster it was L1-98 with boost and L2-134 no boost. i got the owners son here and he is learning to be an electrician. Hew knows enough to agree THAT AIN'T RIGHT. perhaps know I can get it fixed and not have to leave. They will not let me touch it.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
An easy test without opening up the pedestal, is to use a 15 amp adapter and plug the 30 into the gfi, then see what voltage you get. It will run the a/c, and maybe the electric water heater long enough for a voltage check.
 

GoldDigger

Moderator
Staff member
Yes digger, that is correct. I can not get it to display like that. 6 pm this afternoon with the A/C, mr coffee, toaster it was L1-98 with boost and L2-134 no boost. i got the owners son here and he is learning to be an electrician. Hew knows enough to agree THAT AIN'T RIGHT. perhaps know I can get it fixed and not have to leave. They will not let me touch it.
Cavie, look at the hot dog (three dot) dropdown menu on the formatting bar. Select the CODE format and put your table inside that tag pair. It forces a monospace font and disables compressing runs of spaces.
 

Cavie

Senior Member
Location
SW Florida
What are the other RV'rs saying or doing?
No one else in the camp understands electricity. All they know is how to turn the switch on. When I plug in my meter and turn on the A/C's they get a very quick lesson. Next door goes from 115/123 to 106/126 with the air on. 92/132 adding the coffee pot. I did some more testing. Voltage to ground. Both my 30 and 20 amp gfi were on L! I did sneek in and fix that at 6 am. 30 amp L1. 20 amp GFI L2. Neutral to ground is 1.4 volts. I can live with that. Why does the transformer increase 1.4 to 17.5 volts n-g.???
 
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Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
No one else in the camp understands electricity. All they know is how to turn the switch on. When I plug in my meter and turn on the A/C's they get a very quick lesson. Next door goes from 115/123 to 106/126 with the air on. 92/132 adding the coffee pot. I did some more testing. Voltage to ground. Both my 30 and 20 amp gfi were on L! I did sneek in and fix that at 6 am. 30 amp L1. 20 amp GFI L2. Neutral to ground is 1.4 volts. I can live with that. Why does the transformer increase 1.4 to 17.5 volts n-g.???
Sounds like bad neutral somewhere, or no neutral
 

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
Neutral to ground is 1.4 volts. I can live with that. Why does the transformer increase 1.4 to 17.5 volts n-g.???
Is the 1.4V N-G with the transformer unloaded and then it goes to 17.5V with loading applied? Is so that would be due to voltage drop on the neutral conductor from carrying the load current.
Or are you comparing the N-G voltage before the transformer and after the transformer when it's loaded in both of those measurements?
If it's the second case you're probably boosting on the neutral side instead of the line side. Measure from the line input of the autotransformer to its line output. You should see the amount of voltage boost. If the voltage measured across the line in and line out is very small then you may be boosting the neutral side instead.
 

GoldDigger

Moderator
Staff member
If the neutral to earth ground offset is comparable to or less than the L1 to earth drop or less than half the change in the L1-N voltage, then it is not likely that there is a problem with the neutral other than being undersized like the rest of the wiring.
FWIW you can also get a passive constant voltage transformer for any equipment that is particularly disturbed by low voltage.
All of the mitigations that you or others undertake serve to improve your situation at the expense of everyone else, since you will be pulling more current than you would at the reduced voltage. Ultimately, if you all use a boost transformer you are at some point risking overloading the site wiring somewhere along the way.
 
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