Thanks, Don, that was the reason for my question. I've had dealings with
large MW motors and getting the right cables for them and in contrast low
voltage, high current applications. Over here, once you get below the
Safety Extra Low Voltage (SELV) limit (meaning isolated and from memory
<42V) regime the rules change, but my memory fails me as to specifics. I
have a feeling that the automotive industry have different insulation
requirements for instance.
David
G3UNA
----- Original Message -----
From: "Don Wilhelm" <w3...@embarqmail.com>
To: "David Cutter" <d.cut...@ntlworld.com>
Cc: <elecraft@mailman.qth.net>
Sent: Tuesday, October 08, 2013 7:17 PM
Subject: Re: [Elecraft] Elecraft Digest, Vol 114, Issue 11
David,
I believe the same codes do apply since they are based on current, not
voltage.
Codes aside, do not take low voltage, high current sources lightly
(particularly batteries) because they are a very large source of energy.
If shorted, molten metal spewing all over is not an exaggeration, it is
real.
That is why the power cables should be fused for the Ampacity rating of
the wire with the fuse placed near the power source. You are protecting
the wire against fault conditions, not necessarily the equipment
connected.
Shock hazards are a different thing - fuses will not help with shock
hazards. True, low voltage supplies may not be a shock hazard, but they
are a hazard just the same because of the high energy available should
there be a fault.
73,
Don W3FPR
On 10/8/2013 1:45 PM, David Cutter wrote:
Are those codes applied to low voltage isolated supplies by law or
are there separate codes for this? In the context of the original
question, the 13.8V dc supply will not have the same shock hazard, though
it may have the same fire hazard, so, perhaps a different code/standard
applies. House wiring requires a high degree of safety because its
potential (risk) for fire, but the risk of fire in isolated low voltage
equipment which is on view (ie not hidden in building cavities etc) is
different.
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