Dear Mr. Wiles,
I'm looking for a little
clarification here, please.
NEC Article# 690-71(b) (1) & (2)--
Is the intent of this article to
prohibit 48-volt systems? If so, why? The battery voltage in these
systems is regularly above 50 volts DC. Or should the phrase "nominal
system voltage" be inserted in there somewhere?
Are "live parts" of batteries
considered "guarded" if the batteries are enclosed in a box or cabinet? Or is the intent to, once again, require
something that doesn't yet exist (such as the ground-fault protection for
roof-mounted PV was)?
I know of no listed or
recognized, or even a practical means of covering battery terminals in a large
bank, while still leaving the cells & terminals accessible for
maintenance.
Also, I see that this voltage
limitation for storage batteries appears only in Article 690. Would
this mean, in a wind-power-only system, that the system voltage for a
dwelling could exceed that 50-volt limit?
I am posting this inquiry to
Home Power Magazine's "Wrench List" for comment. With your
permission, I would like to post your response to this group of folks, as
well.
Thank you for your time, and I
look forward to your response.
Sincerely,
Don
Wallingford
Quicksilver Electrical Service
P.
O. Box 766
Frederick, Colorado 80530
Phone/Fax: (303) 833-4214