Forum Discussion

afidel's avatar
afidel
Explorer II
Jul 03, 2020

marginal park power on hot days

Well, our PD EMS started cutting power around 11am today due to undervoltage. I finally got it to stop by turning off the converter and the fridge circuit breakers and turning the AC from high to low. So, if you're in a park with very marginal power try shedding as much load as you can. We'll turn the converter back on tonight to charge up the battery, I'll probably leave the fridge on propane as that barely uses any even if left on all weekend.
  • Lynnmor's avatar
    Lynnmor
    Explorer
    Jul 05, 2020
    CavemanCharlie wrote:
    Lynnmor wrote:
    The voltage will be the same at both the 50 & 30 amp receptacles.


    No Not Always. I've tried it out.

    It could be because the 30 amp plug gets more use and is more wore out but, I know of one park in particular that I always have to use the 50 amp plug to get the voltage high enough to make me feel more comfortable.


    There can be exceptions, but most are wired to the same feed lines and the only difference you will see is more loss in the small cord to your trailer under load. A worn receptacle can cause resistance and that will show up as heat at the plug.
  • CavemanCharlie's avatar
    CavemanCharlie
    Explorer III
    Jul 05, 2020
    Lynnmor wrote:
    The voltage will be the same at both the 50 & 30 amp receptacles.


    No Not Always. I've tried it out.

    It could be because the 30 amp plug gets more use and is more wore out but, I know of one park in particular that I always have to use the 50 amp plug to get the voltage high enough to make me feel more comfortable.
  • TurnThePage's avatar
    TurnThePage
    Explorer
    Jul 04, 2020
    Good job on the OP for figuring out how to make it work. In the meantime, I just looked at the Hughes Autoformer. It says it may not be compatible with pedestals with GFCI. That sounds a little ominous...
  • CA_Traveler's avatar
    CA_Traveler
    Explorer III
    Jul 04, 2020
    I visit a park that was 30A only. They recently upgraded about half of the sites to 50A. Why not all sites as it was largely a DIY and donation project? The answer was cost. The utility power panel would have to upgrade the incoming power and distribution center and that cost could not be justified.
  • CA_Traveler's avatar
    CA_Traveler
    Explorer III
    Jul 04, 2020
    Consider many 30A (3600W) rigs built (still are?) with 2 ACs and contain a device that does not allow both AC's to run simultaneously because owners don't understand and want tripped CBs. Many of those same rigs had 5600W gens that could easily power 2 A/Cs along with other loads.
  • CA_Traveler's avatar
    CA_Traveler
    Explorer III
    Jul 04, 2020
    Derating generally works simply because all of the pedestals are not at the maximum loads. However, todays rigs generally use more AC power and every summer there are posts about low voltage or tripping CBs. Especially for 30A pedestals.

    In 2004 I had a 50A MH and there were limited 50A pedestals available. Upgrades are expensive but the demand has significantly increased availability of 50A since that time.
  • time2roll's avatar
    time2roll
    Nomad
    Jul 04, 2020
    valhalla360 wrote:
    CA Traveler wrote:
    Actually, the NEC code allows for derating factor and that is common. And the panels main CB would trip to provide protection from overloading and fire.


    The answer is in the middle...yes, they do allow derating on the assumption that not every pedestal would be at peak power demand.

    It's not a 50% derating.

    Also, 30amps is a nominal rating for the outlet Your average air/con only pulls 10-12amps. Add in 3-5amps for fridge and other light loads, and the average rig is drawing less than 17amps, so if voltage is dropping significantly, that implies an inadequate electrical system.
    You are correct it is not 50%.... because it is as low as 41%

    See table 551.73

    http://www.electrician2.com/tables/Table551_73.pdf
  • time2roll's avatar
    time2roll
    Nomad
    Jul 04, 2020
    afidel wrote:
    2ACs per rig has to get really close to averaging out to 4kw per site, 75% load factor on the transformer is a bit too close for my blood, especially since there's going to be other loads like water heaters, refrigerators, microwaves, etc. I mean since you get murdered on peak usage as a commercial user I can kinda understand why the park wouldn't want too much capacity, but pushing the equipment that hard is why we run into these undervoltage conditions.
    50 amp is 12,000 watts. 4kW is closer to 33%.
  • valhalla360's avatar
    valhalla360
    Navigator
    Jul 04, 2020
    CA Traveler wrote:
    Actually, the NEC code allows for derating factor and that is common. And the panels main CB would trip to provide protection from overloading and fire.


    The answer is in the middle...yes, they do allow derating on the assumption that not every pedestal would be at peak power demand.

    It's not a 50% derating.

    Also, 30amps is a nominal rating for the outlet Your average air/con only pulls 10-12amps. Add in 3-5amps for fridge and other light loads, and the average rig is drawing less than 17amps, so if voltage is dropping significantly, that implies an inadequate electrical system.
  • wanderingaimles's avatar
    wanderingaimles
    Explorer
    Jul 04, 2020
    time2roll wrote:
    wanderingaimlessly wrote:
    time2roll wrote:
    wanderingaimlessly wrote:

    Do you really think they will go out at midnight to connect?
    They will start connecting as soon as they arrive and then complain that their AC isn't working, anything but admit it's their own doing.
    Car has a timer. Will be sound asleep.

    They will want to do things and go places, and the 120 volt is slow, so they will be starting asap in most cases.
    It takes 4 days on a Tesla S to fully recharge.
    tesla charge

    and you know the trucks will have even larger banksn needing even more time.

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