On Friday, May 20, 2016 at 5:48:30 PM UTC-4, Uncle Monster wrote:
On Friday, May 20, 2016 at 3:59:25 PM UTC-5, trader_4 wrote:
On Friday, May 20, 2016 at 3:02:29 PM UTC-4, Uncle Monster wrote:
On Friday, May 20, 2016 at 10:57:05 AM UTC-5, bud-- wrote:
On 5/19/2016 3:35 PM, Uncle Monster wrote:

It's hard to get most people to understand that surge arresters actually wear out.

But not likely.

I've taken apart favorite surge strips and replaced the MOV's inside with better ones. I have some strips that fit a certain way in a space and a newer one may not fit. I write the date of repair on the back with a Sharpie. ^_^

MOVs typically fail by starting to conduct at normal voltage and going
into thermal runaway. That is a fire hazard, so since 1998 UL has
required thermal protectors to disconnect overheating MOVs. You
compromised that protection. I would never modify a protector.

Every time an MOV conducts a surge to ground it heats up. I would liken it to bruising. If the MOV gets beat on enough it will fail. Quite often the circuit breaker/power switch trips when the MOV's sink enough current to ground but again, if the MOV's get slammed enough they'll fail. If I take a surge arrester apart and notice the MOV's are discolored, I'll replace them. I've also had the thermal cutouts open up and I replace them along with the MOV's. I have a lot of high end surge arresters at home, some of them have chokes and capacitors to filter out electrical noise. I can usually repair one cheaper than buying a new one because the parts cost me less than a new unit. Back in the late 1970's, I rebuilt some control boards for industrial cranes and the MOV's looked like 2 inch long axial lead molded capacitors. When I was working, I'd replace toasted surge arresters on customer equipment and fix the old ones for my own use. The new arresters have a warranty and I'd always fill out the warranty card and send it in to the manufacturer. I don't like to trash things that I can repair and reuse. ^_^

[8~{} Uncle Repair Monster

Would Uncle Repair Monster care to share his repair knowledge and comment on
W Tom's claim that electronic appliances don't typically use MOVs for surge protection?

Didn't you set him straight? Every modern electronic device that plugs into a wall outlet that I've had apart, has 1 or more MOV's on the 120vac line in. The low voltage powered devices may not have an MOV on the DC jack but there is usually an MOV in the wall wart across the 120vac plug. The last thing I pried apart is a little 5vdc USB wall wart that stopped working and it's a bit bigger than my thumb and it has a tiny MOV soldered onto the circuit board. What do I know? I've worked on and off in the field of electronic repair for more that 40 years so I've seen all kinds of stuff. o_O

[8~{} Uncle Broken Monster

Thank you. Lots of us here have tried to set W Tom straight over the
years, but it's like whack-a-mole or trying to nail jello to the wall.
His insistence that appliances don't typically have MOVs in them for
surge protection is one of the most bizarre and ridiculous claims he's
made so far. I've seen the insides of quite a few appliances to know
I'm right. But it's good to have someone else that's seen a whole lot
more confirm it.