[Elecraft] Elecraft Digest, Vol 114, Issue 11

[Don Wilhelm]

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.