GFP on SDHW pv pump? [RE-wrenches]

[Mark Frye]

Indeed, but in order to capture the full power of the module the fuse 
would have to be rated at about the Imax of the module which would be 
about the same as the Isc so you may as well not have the fuse at all in 
terms of interrupting the ground fault current.

So here we have another massive gap between Code and technology.

Incredibly, if you are running a 100kw system, you would set the GFDI 
trip at what, I forget , 5 amps, 10 amps, 50 amps?

Ok, for a 3kw system the GFDI fuse is 1 amps.  Scale it down to a .003 
kw system and really what rational person would require GFDI in this 
case.

As an aside, in order to be intrinsically safe so yo can be used in 
Classified Locations (explosive)you can run at up to 1.3 watts.


Joel Davidson wrote:
> 
> From the 2005 NEC Code Handbook page 1021: Ground-fault detection and 
> interruption for PV systems should not be confused with the requirements 
> for 
> GFCI protection, as defined in Article 100. A GFCI is intended for the 
> protection of personnel in single-phase ac systems. It functions to open 
> the 
> ungrounded conductor when a 5-mA fault current is detected. In contrast, 
> 
> devices meeting 690.5 are intended to prevent fires in dc PV circuits 
> due to 
> ground faults.
> 
> I haven't kept up with SDHW system developments, but what's wrong with 
> using 
> an in-line, fast-blow fuse on the low-wattage PV module circuit?


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