Every RV surge protector gets a score from 0 to 100% built from five factors, which maps onto the 5-point rating shown on the site (a 0% score would be 1.5 stars; a perfect score, 5). Each factor is scored against fixed reference points, not against the other products in the list, so adding a new model never moves another model’s rating. Protectors are grouped by service, 30 amp and 50 amp, on the same scales apart from price.
| Factor | Measures | Weight |
|---|---|---|
| Protection | voltage cutoff, miswiring detection, restart delay, replaceable module | 35% |
| Surge rating | joules of surge absorption | 10% |
| Monitoring | volts and amps display, app | 10% |
| Price | price of the unit | 20% |
| Warranty | warranty length | 25% |
Where the numbers come from
Surge ratings, voltage cutoffs, protection features, displays, apps and warranties come from the maker’s product page, brochure, manual or the maker’s own copy on retailer listings. Prices are checked at Amazon, the maker’s own store and RV retailers, and the lowest is used.
The factors
Protection adds up the protection features the maker lists: 50% for a high and low voltage cutoff (what makes a unit an EMS), 20% for miswiring detection that refuses to connect on an open ground, open neutral or reverse polarity, 15% for a restart delay that protects the air conditioner compressor after a fault, and 15% for a surge board or module that can be replaced after a strike without buying a new unit. A unit that only lights up to warn of bad wiring doesn’t get the miswiring credit.
Surge rating is the maker’s joule rating, on a log scale: 800 joules scores zero and 4,000 joules full marks. For 50 amp units it’s the maker’s total figure for the unit.
Monitoring is half for a display that shows volts and amps and half for a Bluetooth or Wi-Fi app. Indicator lights alone score zero.
Price is the current price, on a log scale, against each service’s own range. For 30 amp units $350 scores zero and $80 full marks; for 50 amp units $550 scores zero and $120 full marks.
Warranty is the maker’s warranty: 1 year scores zero and 5 years full marks. A lifetime warranty counts as full marks.
What isn’t scored
The service rating, portable or hardwired mount, the exact cutoff voltages, weatherproofing and a lock or locking bracket are listed but not scored.
Missing data
If a figure isn’t published, that factor gets the neutral middle score (50) and the product page marks it as estimated. The exception is warranty: a maker that doesn’t publish one gets no warranty counted, so that factor scores zero, the same as the shortest warranty on the scale, and is marked estimated. Protection counts only the features the maker confirms; it’s neutral only when none of them is published either way.
Ties and discontinued models
Products are ranked by score within each group. Discontinued models stay listed but rank below every current model and can be hidden with the “Hide discontinued” filter.