On Friday, May 20, 2016 at 3:30:28 AM UTC-5, westom wrote:
On Thursday, May 19, 2016 at 5:35:17 PM UTC-4, Uncle Monster wrote:
It's hard to get most people to understand that surge arresters actually wear out.

All protectors wear out. Those that are properly sized remain robust and functional ten and more years later. Especially since destructive surges happen maybe once every seven years. And since properly sized 'whole house' protectors are rated at least 50,000 amps.

That destructive surge (incoming to every appliance) means a near zero protector may even fail catastrophically. MOV manufacturers are blunt about this. No protector must fail catastrophically. But grossly undersizing means a surge too tiny to damage appliances can destroy that protector. It promotes a myth that a protector must be replaced frequently. Protectors wear out. Effective protectors remain functional for decades.

I've replaced a lot of MOV's in equipment and have done a lot of work in telecom where I had to protect not only power supply but phone lines. I never lost a commercial phone system, computer or point of sale system to lightning once I gave it the Monster treatment. One of the worst problems I ever had with phone or network wiring was caused by rats and mice. Those critters did more damage than lightning. ^_^

[8~{} Uncle Power Monster