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Topic: Power Pedestal Issues (Read 597 times) previous topic - next topic

Power Pedestal Issues

First I'd like to ask the group is there a way for me to measure how many amps are available at the pedestal. I'd like to know if there is 20, 30, or 50 amps before I plug in. Merely having the correct plug (RV 30 or 50) installed does not always guarantee the proper amps. Am I correct? My OEM Power Line Monitor shows Volts. It can be as high as 125v and dips, when I have appliances drawing power, to a low of XXXv. Am I correct when I say I am going to see 125v regardless of the amperage? A 20 amp house circuit will have 125v, a 30 amp circuit will show 125v. So how do I know when I can run both AC's, a microwave, and my wife hair dryer all at the same time?

Our relatives (wife's side of the family) have full hook ups which they have graciously offered to us any time we visit. We plan to visit often. The pedestal plug is a standard RV 30 amp plug. I use an adapter. I don't want to look a gift horse in the mouth but I have my suspicions it may be only 20 amps. We never had a problem running a microwave and air conditioning plus fridge on 110v in our 30 amp service SOB but we have had a lot of issues when our FT is plugged in to this pedestal. I try to manage our power needs by only running one AC at a time. Shutting off the coffee maker before turning on microwave etc. Even turning off inverter charger and placing fridge on propane.

This trip when we we were getting ready for our departure I turned the block heater on a few hours before we started the engine. I forgot it was on and left the on/off switch in the on position. It wasn't powered since I removed the shore power. When we plugged into the pedestal at my relatives home it was energized again. I never noticed the illuminated light switch at the foot of the bed. It was covered by a bed skirt. I did notice the power line monitor was reading between 113v and 118v. I now suspect it was the block heater drawing power. I only found the switch was on when I lifted the bed to check the EMS after we started having problems.

The next day we began experiencing all kinds of brown outs. The microwave is set up to work on both shore and inverter power. The ATS would change to the inverter and then back again to shore power. It was very disconcerting to hear the loud clunk the ATS makes when switching and watch the micro shut off then turn on then shut off etc. My wife was cooking pies for Thanksgiving dinner and I had to pull the shore power plug and start the genny. All this time I was unaware the engine block heater was drawing some 1400 watts of juice from the power source.

Here is what I think happened.  With so much current being drawn (block heater, refrigerator, microwave and don't forget the inverter trying to charge the batteries) my Progressive Industries EMS shut down the power entering the coach and the ATS changed over to inverter power then when the EMS sensed the power back on the line it allowed shore power back into the coach where the ATS switched back to shore power. This continued until I shut the microwave off.

I think my problems are over for now, but I still would like to know if I can measure available amps.

Thanks
Happy Thanksgiving
Ed
Ed and Michele
2000 U295  36'  (Build #5600)
8.3 ISC 350HP.
2012 Jeep Grand Cherokee (Toad)
2001 Lance Truck Camper (Sold)
2001 Lazy Daze (Class C). RK Floor Plan (Sold)

Re: Power Pedestal Issues

Reply #1 –
the important part is the size of the breaker, the length and gauge of wire used to run to the pedestal. If any of these are off, its going to cause issues. That is what you need to look at to determine available amps. If anything is sub par, you wont be able to get a full 30 amps. Also if the plug or socket are dirty, corroded, or have a poor fit, they will limit how much current can pass.

113v is not so low that it would cause problems, but if your ems is kicking in, it is probably dipping a lot lower.
Matt
95 U300, 78k miles
Cat 3176 Jake Brake, HD4060.

Re: Power Pedestal Issues

Reply #2 –
Amps will be based on breaker in panel I suspect too small a gauge wire or other wiring related issue such as loose connection in pedestal
Tim Fiedler    2025 LTV Unity MBL on Order
2000 Chevy Tracker 2 Door Convertible 4WD Now lifted 4.5"
1985 Citroen 2CV6 Charleston
Murphy Rebel on wheels with 175HP Titan
Cessna P337
1980 48' Westport MY (!/4 Share)

Re: Power Pedestal Issues

Reply #3 –
Your EMS display will show volts and amps and any faults it reacts to.

A 30 amp connection has 3600 watts (nominal) power available.  You have to manage loads especially if you are charging batteries.
A 50 amp connection has 12,000 watts (nominal) power available. You should be able run just about everything on a 50 amp connection.

The EMS will disconnect if the voltage is too low or not connect at all if there are any wiring problems.  Check the display for fault codes.

The general rule of thumb for a 30 amp connection is one bigger appliance at a time.

Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Power Pedestal Issues

Reply #4 –
We were camp hosting up north, and in doing my rounds, noticed a power & water pedestal feeding a coach that just came in. I knew there was no power/water at his site and stopped. Turned out the pedestal was a phony he'd made up to blow everyone's minds at dry camps. Sure blew mine!  :)
1993 U-240 "La Villa Grande"..CAT 3116 w/ Pacbrake PRXB...Allison 3060 6-speed..
Previous: 1983 Airstream 310 turbo diesel, 1979 Airstream 280 turbo diesel
                                      Build # 4297
                                      PNW natives
                      Home base:  'Cactus Hug' (Ajo, Arizona)
                        DW Judy & Chet the wonder dog
                        Full-Timers 'Sailing the asphalt sea'

Re: Power Pedestal Issues

Reply #5 –

You were simply drawing too much current for a 30 amp connection.

You could use an ammeter to measure your current or you could permanently install something like this-

Amazon.com: DROK® Digital Current Voltage Multimeter AC 100-300V 100A...

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.
Robert
Build # 5304
1998 34' U270 Cummins 6CTA8.3

Re: Power Pedestal Issues

Reply #6 –
I don't know of any way or device to detect or measure how many amps are available on an outlet.  Yes, all outlet sizes will have the same outlet voltage.  Exception: on a 50 amp outlet you should see 240 volt measured from one leg to the other leg, but each leg will still measure 120 volts when measured from neutral to that leg.
With increased amperage draw you will see some voltage drop.  When the EMS triggers on low voltage you know you've pulled too many amps for the circuit regardless if the breaker as tripped or not - assuming there was adequate voltage before loads were applied.

If wired correctly, a 30 amp outlet should have one leg (or connection) of 30 amps.  And a 50 amp outlet should have two legs with 50 amps each.  At an RV park you should be able to expect this.  At a friend or relatives home I like to know where the breaker is and what size it is and them monitor my amp draw.  Your experience does sound like the outlet did indeed have 30 amps but I would guess the wire might not be as large as it should have been for the length run to the outlet - thus the voltage drops (triggering the EMS) without tripping the house breaker.  Ideally the breaker should trip before the voltage drops too low.  My guess is if you were reading the amps, you would have quickly noticed that the block heater was left on.  I've done the same thing more than once by accidentally kicking the switch on.  I now have a cover over the switch.
John Fitzgerald
1991 U300 (SAI) Side Aisle Island Bed 40'
Detroit 6V92 with Allison Retarder
Meridian (Boise), Idaho

Re: Power Pedestal Issues

Reply #7 –
Remember the 80% rule, a 30 amp line is only good for 24 amp steady load.

Re: Power Pedestal Issues

Reply #8 –
Just thought I would link these two together. The two subjects may be different but this is pretty much what I am experiencing. Maybe my problem is the ATS.

Newer microwave/convection trips ATS?
Ed and Michele
2000 U295  36'  (Build #5600)
8.3 ISC 350HP.
2012 Jeep Grand Cherokee (Toad)
2001 Lance Truck Camper (Sold)
2001 Lazy Daze (Class C). RK Floor Plan (Sold)

Re: Power Pedestal Issues

Reply #9 –
Quote from: Dave M –
Remember the 80% rule, a 30 amp line is only good for 24 amp steady load.

My understanding is that the "80% rule" applies to continuous loads such as motors, lighting or any load expected to be on continuously for three hours or more. I believe a motorhome would not be considered a "continuous load."
David and Carolyn Osborn
1995 U320C SE 40' Build 4726 Feb 1995
FMCA 147762
Motorcade 17186