Last Changed 3/23/2009
RV park electricity is a commodity that quite often does not meet
necessary standards. Your RV has several electrical and electronic
devices that can be damaged by bad power. It is wise to protect
your RV with a power management system.
The things to check the park power post for:
- The voltage present (too low <104 volts? too high > 132 volts?)
- a good ground
- a good neutral
- the line frequency (60 Hz?)
We have a Good Governor, that in the past, we used to test park
power before we connected the RV power cord. We did not have the
adapter to test both legs of the 50 amp outlet but we felt
comfortable testing the one leg.
The Good Governor checks voltage and line frequency.
The PowerPal came onto the
market after we had the Good Governor. This is a good testing
tool. It plugs into a 50 amps outlet so it can check both legs
unlike the Good Governor without adapters. The PowerPal also checks
Ground and Neutral. The PowerPal has a display plus it speaks the
During one of the sessions at
Life On Wheels, taught by Steve Savage, we were convinced that
our RV was at risk without a power management system.
The above tools check the park power post before connection. A
power management system continues to monitor park power while you
We chose the Progressive Industries PT50C version of its EMS (Electrical
Management System) for these reasons:
Micro-processor driven with a led display to show current leg
voltage, current and frequency, and any error condition.>
High voltage protection. The EMS will disconnect park
power from the RV if the line voltage goes over 132 volts.
High voltage can burn out electronic devices.
Low voltage protection. The EMS will disconnect park power
from the RV if the line voltage drops below 104 volts. Low
voltage can burn out motor devices like your air conditioner
compressors. Electrical devices really consume power
(watts), the product of voltage (volts) and current (amps).
If the voltage goes down, then the current used will rise to
maintain the same power. This extra current draw is what
burns out devices.
Surge protection. The EMS will protect your RV and devices from
voltage spikes. Spikes generally occur from lightening;
but there are other sources of spikes.
Wiring error protection. If the EMS senses that the park
wiring is reversed, it will not turn on park power to your RV.
Open neutral protection. If the EMS does not find Neutral
continuity, it will not turn on park power to your RV.
Open Ground protection. If the EMS does not find Ground
continuity, it will not turn on park power to your RV.
AC frequency protection. If the AC frequency drops below
51 Hz or goes over 69 Hz (60 Hz +/- 9Hz), the EMS will
disconnect your RV from park power. AC frequency errors
can harm motors.
220 volt protection. The 50 amp plug on a RV power cord
can be plugged into a 220 volts outlet. The RV is wired
for 110 volts. If the EMS senses this error, it will not
connect park power to your RV. Actually this is more likely to
happen when using a 30-50 amp adapter and mistakenly plugging
into a 220 volt 30 amp outlet.
The Progressive EMS is far more than just a surge protector.
We have already benefited from the Progressive EMS. We were in a
park with a poor neutral. When we turned on a load like an air
conditioner, that load on one leg of the park power would bring the
voltage down a bit This is normal. However, with the poor neutral,
the voltage drop on one leg showed up as a voltage increase on the
other leg. Because the Neutral was poor, the voltage drop on the
load leg was more than normal and the other leg would climb over 132
volts. Had we not had EMS protection, we would not have noticed the
high voltage until something burned out.
The Progressive EMS is available in hard wired and portable styles.
The hard wired model is installed in you RV inline with the park
power input. The hard wired style can have its display built into
the unit or as a remote display that can be mounted in a convenient
location inside the RV. There are 50 amp and 30 amp models.
The portable model plugs into the park power post and the RV power
cord is plugged into the EMS. There are 50 amp and 30 amp models.
We chose the portable unit mainly because finding a place to
install a hard wired model in Tige
would have been difficult. This definitely an item to plan for if
you are ordering a new RV. The RV manufacturer can either install
the EMS or at least leave space where it is easy to install a hard
wired unit inline with the input power.
When the park power breaker is turned on (the breaker should
always be off when plugging in the RV power cord), the EMS will
sample the park power for a short time. After several seconds, when
the EMS has determined that the park power is safe, the EMS will
connect park power to the RV.
If the EMS has to disconnect park power from the RV, the EMS will
wait 136 seconds, then check park power to see if it is okay again,
and if it is, reconnects park power to your RV. This delay protects
your air conditioners. If power is reapplied to quickly to the
compressor, pressure built up in the compressors can resist the
compressor startup and damage the compressor.
If the EMS acts upon an error condition, it will retain that error
condition in its display memory so that you can see if you are
having electrical problems. The display is built into the portable
models. For the hard wired models, the display is in a remote
module that is mounted on an interior wall of your RV.
The Progressive EMS is not low cost and having it hang on a park
power post makes it available to thieves. The PT50C comes with a
security bracket, a piece of steel the PT50C is mounted through with
another hole for a locking device. We use a cable locking device.
We pass the locking cable through the security bracket.
More importantly, we have found that using the locking cable, relieves
the strain on the EMS plug in the power outlet.
We found the Master Lock Python 8413XDPF cable lock had an end
that will fit through the security tab of the Progressive EMS. The 6' length version of the Python gave us the
ability to wrap the locking cable around the park power post and the PT50C EMS unit twice for extra security.
We still use our Good Governor. Most of the AC devices we
normally use are on the leg that is also driven by the inverter. If
the park power fails, the inverter immediately switches over and we
don’t even notice the switch. We plug the Good Governor into an
outlet that is not on the inverter leg. If the display is not
illuminated, we know that the park power is not on.