[K3CAL] [SMCARA] Electrical Safety

[Dave]

Forwarded from St Mary's County Amateur Radio Association reflector:
FYI
Message: 6
Date: Fri, 30 Oct 2020 12:37:02 -0400
From: Tom <w4okw at md.metrocast.net>
To: smcara at mailman.qth.net
Subject: [SMCARA] Electrical Safety
Message-ID: <d47ab843-2904-0523-0bcb-c418497b1575 at md.metrocast.net>
Content-Type: text/plain; charset=utf-8; format=flowed

?An acquaintance of mine, W7UUU, recently suffered a devastating fire
in his garage/shop/hamshack and basically lost everything. He is an avid
collector and restorer, so this is a lot of irreplaceable stuff. This
building was detached from his house, so it was not affected.

The culprit was a cheap, surge protected power strip with a plastic
case. He was using it to power a 65 inch TV set (which consume lots of
power, I assume) and it flamed and set the place on fire.

Surge protected power strips use devices called MOVs (metal oxide
varistors) to dampen the surge on the AC line. They have a finite life,
and deteriorate with each with each surge absorbed. When they fail, they
usually short and explode, usually tripping the circuit breaker, but not
in time to prevent flaming. The plastic case and wiring sustains the
fire and away it goes. Surge strips that have metal cases are safer, as
they contain the flames from the exploding MOV. A better approach is to
have an electrician install a whole house surge protector in the service
box and forget about the power strips.

So, go around your house and toss out (after cutting off the plugs) all
of those cheap Chinese plastic power strips now! Replace them with metal
ones or even better,? none if you can swing it. As you check your house,
see if the strips are warm to the touch. Bad sign! While you are on this
hunt, check all your outlets to see if any are warm.? Same for extension
cords.

I had an issue with dimming lights in my house in Florida every time
someone used an iron or hair dryer in the bedroom. Fortunately my
neighbor was an electrician (and a ham WB4CGD) and he tightened a lot of
loose connections in the outlets in the house. He also found a few that
were the "strip and push" connections and replaced them with screw
terminals.? He tightened all the connections in the breaker box also.
All house wiring will loosen up over time. Fix it if you are comfortable
working with AC house wiring or call an licensed Electrician.

Many AC operated devices use MOVs, such as Astron, etc. power supplies.
Should be OK if they have steel cabinets and circuit protection. Dave,
W7UUU, went so far as to clipping all MOVs from every bit of electrical
gear in his house! No exploding MOVs at his QTH!

As Reddy Kilowatt says: "Stay safe out there".

73 de Tom/W4OKW (who spent a high school summer vacation as an
electricians helper)



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