Mailing List lml@lancaironline.net Message #4499
From: dfs <dfs@gateway.net>
Subject: Sizing of breakers/fuses
Date: Mon, 24 Jan 2000 22:57:28 -0800
To: Lancair List <lancair.list@olsusa.com>
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To Ed Sikora:

When you plan for the sizing of breakers and/or fuses, just remember one
cardinal point - breakers and fuses are not in there to protect the
connected item but to protect the WIRING that connects the items to the
power. With that in mind, each item should be connected with wire of the
correct size for the expected load, then the breaker/fuse selected to allow
that continuous current to flow without opening. For the open wiring that we
use on our Lancairs, i.e., any wire not enclosed in conduits, a good rule of
thumb is to size it at around 500 circular mils per amp for its continuous
expected load. Information re: wire size vs circular mil area is available
from many sources (I think you can find it in the back of the AC Spruce
catalog but if not, certainly in one of Tony Bingeles' books).

Most common breakers/fuses are designed to open in milliseconds at 500 to
600 % load, characteristic of a short circuit, and will protect your wiring
well enough to fly another day (once you've found and eliminated the short).

With this in mind, sizing your breakers/fuses should be easy to do.

Dan Schaefer



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