An electrical power surge is just that… a jolt of high-voltage electrical energy on the power line. It may be from a lightning strike or problems at the power source. Both of these causes are most unusual.
Still, genuine power surges can and do occur. The most common from faulty power company transformers or downed power lines. “Surge Protectors” can prevent some or all of the damage. There are various ways to design surge protectors, some more efficient than others.
Many surge protectors are available. From simple single circuit types ($10-25) that protect a single appliance to massive things that will protect all circuits in an RV (big$). Most RVers are interested in a surge protector that will protect the entire RV. Fortunately, we’re only interested in a 30-50 amp capacity and such protectors are reasonably priced though not cheap though.
The least expensive surge protectors generally available in RV stores cost around $100. The good points: Inexpensive, has appropriate RV-style cable connections, includes a built-in GFI (Ground Fault Interrupter) that will shut it off if there’s a “short” in the circuit. Bad points: Most of these are sealed and cannot be repaired which is just what you don’t need in a surge protector that “sacrifices” some of its components under surge. The basic components are cheap around $10 but if you can’t replace the parts then, you’ll need to replace the whole protector for another $100.
Better surge protectors in the same outdoor style or for connection in the RV at the electric panel (keeps people from stealing them) can be bought from several companies (and will cost more). At least two advertise in many RV publications. Some of these sophisticated surge protectors reset themselves or are manually resettable, some are repairable and some models include extras, such as high and low voltage cutoffs and a feature to protect your system against generator spikes.
Insist on the Underwriters Laboratories 1449 standard (it should be printed on the box). Further, look for a UL listing of three ratings: Hot-neutral, Hot-Ground, Neutral-Ground (the three circuit pairs that need to be protected) not just one (Hot-Ground) as found in cheaper protectors. The UL Standard only means the protector meets minimum standards. For example a UL 1449 might allow a pass-through (brief) of 500 volts at surges in the thousands of volts and amps. A really good surge protector should allow no more than 300 volts pass through or less. “Joules” are another consideration. The simple rule of thumb here is the more the better.
See inexpensive RV surge protectors from Amazon.com