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Re: [RFI] CHECK your grounds.

To: "Michael Coslo" <mjc5@psu.edu>, "RFI RFI" <rfi@contesting.com>
Subject: Re: [RFI] CHECK your grounds.
From: "Paul Christensen" <w9ac@arrl.net>
Date: Thu, 27 Jan 2011 09:42:50 -0500
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
>"but when I bought my place, I replaced all the outlets. Not only got nice 
>new tight outlets, but I got to look inside at the wiring.

That's a good practice.  I recently changed out all the outlet's in the 
dining room of a friend's home.  Each receptacle contained a combination 
screw terminal with optional "spring-contact" for quick installation  When 
the spring-contact is used, the wire is stripped to proper length and 
inserted into a hole in the back of the receptacle where the spring keeps 
pressure on the inserted wire.  To save on installation time, the screw 
terminal is not used.

That works fine for a while, until strange things start happening on the 
branch circuit feeding all those receptacles.  In his case, a lamp that was 
plugged into the end of the string dimmed to nearly no light when another 
lamp was plugged in to a receptacle closer to the branch feed.  That's a 
sure sign that contact resistance is building between daisy-chained 
receptacles.  It's not nearly a problem when the receptacle screw terminals 
are used.

I have not checked a recent edition of the NEC, but since its inception, 
NEC's purpose is to ensure public safety and minimize the risk of fire/smoke 
by establishing reasonable premise wiring standards.  The long-term use of 
pressure-contact receptacles almost guarantees that fire/smoke will result 
one day.  If not already banned by the NEC for home/commercial premise 
wiring standards, they should be.

Like you, my shack's wiring and receptacles have been upgraded.  I'm using 
20A hospital grade duplex outlets, each fed by its own 20A branch circuit 
back to the breaker panel.  The amplifier receptacles are 30A 4-wire 
twist-lock, each fed with #8 AWG back to a dedicated 30A 2-pole breaker. 
The hospital-grade types are overkill and very expensive.  Any of the 
industrial-grade types will be a big improvement over the garden-variety 
types sold at home improvement stores for under a buck.

Paul, W9AC


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