[RE-wrenches] Current limiting fuse at battery bank

[Tom Ruscitti]

On battery based systems I always install a Class T fuse as close to the 
battery bank as possible. 690.71(C) is a little vague in requiring a 
current limiting fuse only where the available short-circuit current 
from the battery bank exceeds the interrupting ratings of the inverter 
breaker. Inverter breakers vary in their interrupting ratings and 
battery banks are big current sources when things go wrong, so it's just 
a sensible best practice. My question is about service work on systems 
we didn't install. We're quoting the second job this year for battery 
replacement where there is no current limiting fuse installed. It's 
always a tough question to judge what extra work might be required when 
you touch another contractor's system, but does anyone have an opinion 
about recommending or requiring the installation of a fuse at the 
battery box as part of the battery replacement?

Thanks,

- Tom

-- 
Tom Ruscitti
Senior Engineer

Taitem Engineering, PC
110 S. Albany Street, Ithaca, NY 14850
Mobile: (607) 220-7022
www.taitem.com