Review on POWSAF RV Surge Protector 30 Amp: Power Defender Voltage Protector/Monitor with Surge Protection (4100 Joules) - Designed with Convenient Handles… by Trey Michaels

Works great as intended, connect to power first, watch the digital display double blink green, open neutral green left only, open ground green right only, red Reverse polarity light on left side only and no green or neither red nor green on either side indicates no current. Keep in mind that this particular 120 volt is 30 amps only you will need to buy 220-50 amps for large RV's. This is great for camping. I've camped enough in different states and seen what happens when people plug into a camping box only to find out there are grounding or outlet issues and that alone can cause serious problems for a camper who could potentially burn out. Refrigerators , air conditioners , heaters , retractable exits , electric stairs , awnings , washers and dryers and computers -- the list goes on , even lightning strikes . Remember to always leave the breakers in your installation when plugging in this appliance and checking it for the correct wattage and voltage, you'll save yourself a lot of headaches, money and wasted time. The cost of one of these is well worth the money compared to what you would pay for a possible reinstall if you burned it or for the costly repairs and lost time you incur. I use surge protectors on all of my lighting cords, on my external TV, on fans, and on all of my power strips. They are worth their weight in gold, especially when it comes to electronic devices, mobile phones, laptops, printers and home PCs that are taken on trips.