[RE-wrenches] Integrated GFDI (branch from Finding Ground Faults)

[Kent Osterberg]

Steve,

A PV system GFDI integrated into the charge controller certainly 
simplifies charge controller installations. Unfortunately every charge 
controller that has done that has failed to correct a serious flaw in 
the operation of the GFDI: under a ground fault circumstance, the 
energized PV negative wire (and all those wires that are still connected 
to it) remains a serious safety hazard. I can tolerate that hazard in 
the PV system wiring; the PV modules are energized by sunlight so there 
will be energized wires. But energized wiring running past the GFDI 
should not be tolerated. NEC 690.5(C) requires a label that is visible 
from the batteries warning that, if a ground fault is indicate, normally 
grounded wires may be energized. That's a good warning for someone that 
might be doing maintenance on the batteries. Trouble is the dc wiring to 
the inverters, lights, refrigerator, or anything else may also be 
energized. It's a dangerous circumstance that isn't necessary and 
shouldn't be allowed. If the external GDFI device were to simply open 
both PV+ and PV- conductors, there would be no hazard except between the 
GFDI and the PV array. The NEC, as now written, even allows both 
conductors to be opened. It's an easy fix, at least with the external 
GFDI it is an easy fix, to a design flaw that has the potential to kill 
someone. Outback shouldn't simply put a GFDI in the charge controller, 
they should design one that is safe too.

It is safe to return to the list now. The rant is over.

Kent Osterberg
Blue Mountain Solar, Inc.
www.bluemountainsolar.com


On 5/23/2012 12:18 PM, Steve Higgins wrote:
> From what I understand, future controllers from Outback Power will 
> incorporate the Ground Fault detection into the controller.
> Steve Higgins
> Sales Application Engineering Mgr
> Direct 360-618-4313
> Outback Power Technologies
> 5917 195th Street NE Arlington, Washington 98223
>
> ------------------------------------------------------------------------
> *From:* re-wrenches-bounces at lists.re-wrenches.org 
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of 
> *William Miller
> *Sent:* Wednesday, May 23, 2012 11:22 AM
> *To:* RE-wrenches
> *Subject:* Re: [RE-wrenches] Finding ground faults
>
> Steve:
>
> IMHO, a brilliant suggestion.
>
> William Miller
>
>
> At 11:19 AM 5/23/2012, you wrote:
>> Steve,
>>
>> It would be appropriate for the GFDI to have 80-amp rated contacts 
>> that do not have an over-current trip mechanism. IMHO, the fact that 
>> they can trip on over-current and unnecessarily interrupt the dc 
>> system bond is a serious design flaw.
>>
>> Kent Osterberg
>> Blue Mountain Solar, Inc.
>> www.bluemountainsolar.com  <http://www.bluemountainsolar.com>
>
>
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