GFP on SDHW pv pump? [RE-wrenches]

[Joel Davidson]

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Ground the array. Don't ground the array. Put a GFDI on residential rooftop 
arrays. Put GFDI on all arrays. Set your Voc to record low temperatures. Set 
your Isc to 1.25. Set your Isc to 1.56. Move the cheese. Put the piano by 
the window. Move the piano away from the window. But whatever you do, make 
PV better quality, faster installed, cheaper for the customer, and 
profitable for a sustainable industry. Get involved. See 
http://www.solarabcs.org/stakeholder_mtg_presntations/index.htm

----- Original Message ----- 
From: "Mark Frye" <markf at berkeleysolar.com>
To: <RE-wrenches at topica.com>
Sent: Friday, November 16, 2007 11:41 AM
Subject: RE: GFP on SDHW pv pump? [RE-wrenches]


>
> 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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