An electrical surge—at least in terms of what a surge protector will protect against—is a sudden and large (generally huge) increase in voltage, oftentimes of only a very short duration—maybe only milliseconds.
It’s the type of surge caused most often by lightning hitting electrical equipment or by certain failures—or faults—within the electrical system itself.
A surge protector may or may not protect against any particular surge. Different surge protection devices have different ratings. Having a surge protector in place is better than having nothing at all. But, does a surge protector alone provide adequate protection?
There are a variety of other electrical malfunctions that can be identified with a simple outlet tester.
An EMS (Electrical Management System) device can protect against additional damaging conditions that a surge protector will not protect against and that an outlet tester will not detect.
Let’s start first with the very basics of 120V AC power, the type found at home and in your RV. There is a hot wire (the source of the electricity), a neutral wire (the return path to the source of the electricity, thus making a complete circuit), and a ground wire which is provided as a safety measure and will route the power in the circuit to ground (literally into the Earth) in the event of a wiring failure.
A tester will test an outlet and indicate if there are wiring problems present among any of the three wires mentioned above and their associated connections:
- Open (disconnected) ground wire
- Open neutral wire
- Open hot wire
- Hot and neutral reversed
- Hot and ground reversed
- Proper and normal connection
More surge protector abnormalities
Additional abnormal conditions can be present and are not necessarily unsafe for the occupants of the home or the RV but over time can be very bad for the equipment particularly for refrigerator and air conditioning compressor motors.
The following abnormal conditions must be protected against: High or low voltage and high or low frequency.
Most EMS models will protect against abnormal voltage conditions and some also protect against abnormal frequency conditions. A surge protector will not protect against any of these four conditions.
It seems obvious that high voltage is a bad thing. Just as high water pressure will rupture a water hose, high voltage will damage electrical equipment.
But why is low voltage a bad thing?
Electrical components run on power (watts) which is a combination of both voltage (volts) and current (amperes or amps). At proper voltage, an electrical device especially a motor will draw enough current to operate properly.
As the motor is being asked to do more work, it will draw more current. If it becomes overloaded, it will draw too much current and the circuit breaker will trip, thus protecting both the motor and the wiring.
Some more advanced motors will even have internal protection devices that trip and reset automatically.
Let’s say the voltage at the campground is low. The motor will start to draw enough current to still do the work it is being asked to do. As the voltage drops, the motor will draw more and more current.
Current is what causes the motor to heat up. If the motor runs for an extended period at low voltage and high current—but not high enough to trip the breaker—it will heat too much and damage itself.
However, this damage may not occur right away. Repeated conditions of low voltage will cause the motor to damage itself little by little until it eventually fails.
An EMS device senses this low voltage condition and will trip the power at a preset voltage to prevent motors from damaging themselves.
What about frequency?
The standard electrical power utilized throughout most of the world is alternating current.
In the U.S. and Canada, power is delivered to the home at 120 V ac and 60 Hz (the abbreviation for Hertz which stands for cycles).
In Europe, the standard is 240 V ac and 50 Hz.
The frequency is simply a reference to how many times per second the voltage alternates, hence the term alternating current. (The voltage and the current both alternate.)
Many devices depend upon that 60 Hz as a timing reference to properly do whatever they do.
Electric wall clocks, electric light timers, traffic signal timers, telephone company switching equipment, radio receivers, etc., all depend on a very steady and accurate 60 Hz as a reference so they can, in turn, remain accurate. (More modern Equipment tends to utilize internal timers or reference signals from the GPS satellite system for high-accuracy timing.)
The fact that so many devices need reliable 60 Hz power is the reason the non-inverter type generators have to run at 3600 rpm (revolutions per minute) regardless of how much load is on them. If they only ran at 3000 rpm, the frequency would only be 50 Hz.
What about high or low frequency?
A high or low frequency condition might not be damaging to the particular device but it could cause the device to act improperly or it could damage the equipment that the device is controlling.
To summarize, yes a surge protector is good, an EMS is better and an EMS that also protects against abnormal frequency conditions is better still.
Regarding that circuit tester mentioned above, once it is known that the RV is plugged into properly wired shore power as determined by an EMS device, it is an excellent idea to go around and check all the outlets in the rig periodically.
Unlike a home, the wiring in the rig is subjected to all the vibrations and temperature variations that come along with the RV lifestyle.
Insulation on wires can rub through and expose bare wires, connections can become loose, and any of the dangerous conditions already mentioned can develop over time, conditions that may be harmful or even fatal, and must be avoided by taking the proper precautions.
And if you have electric heaters plugged in, you might want to review this post again and get it organized.
Here are a few links that may help you prepare for your next RV trip:
- Is Your RV Protected from Electrical Issues?
- Maintain Your RV: What You Absolutely Need To Know To Avoid Disasters on the Road
- The 10 Essentials Every RV Owner Should Buy Before Their First Road Trip
- 35 Little Things to Remember to Pack for Your RV Road Trip
I am not a product of my circumstances. I am a product of my decisions.