Surge protectors or fire hazard

From: Joe <rigdonj_at_cfl.rr.com>
Date: Fri Dec 20 09:10:02 2002

   The MOVs used in these things fail by shorting. When they short, they put a short directly across the AC line. Building one of these things without fuses or circuit breakers in BOTH legs is just looking for trouble. You should report these incidents to your state and local fire marshall, as many consumer agencies as you can find and the store that sold them to you.

   You need a protective device (fuse or circuit breaker but fuse prefered) in BOTH AC legs since the power surge can be differeential (across the AC line) or common mode (where the voltage increasses in both AC lines). Don't put a protective device in the ground line!

   FWIW I pick up old power supplies and surge protectors and save the MOVs out of them. Then anytime that I work on a computer or other electrical device I add a MOV across the AC line and a MOV between each AC line and ground. I also add fuses in each AC line ahead of the MOVs. Even with these changes I still use surge protectors whenever possible, call it double insurance. I live in the lightning capital of the world (central Florida) and I've yet to lose a computer or TV to lighting despites numerous close hits. I've lost plenty of MOVs and surge protectors though.


      Joe


At 04:39 PM 12/19/02 -0800, you wrote:
>Hi
> I've just seen the third surge protector blow
>up and this time, it almost started a real fire.
>I've had two of these go up in smoke that were
>in metal strips. These generally make a lot of
>smoke but I think the metal spreads the heat enough
>that the fire danger is small. Now, most of the
>newer ones are made from plastic. The last one
>that just burned, started a small fire on the back
>side of a chest of drawers. Luckily, the chest
>didn't stay lit. It did charcoalize one of the feet.
> While these things come with a 15 amp breaker,
>the MOV's fail and draw something less then what
>is required to blow the breaker.
> I wonder if any of the fire prevention groups are
>looking into these time bombs?
>Dwight
>
>
>
Received on Fri Dec 20 2002 - 09:10:02 GMT

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