RE; Breaker hold down kit [RE-wrenches]

[EH Roy]

Vince,

Yep you've got a problem - been there. We were not able to find a retainer
kit for Murray breakers and were not able to talk a utility inspector out of
the need for one (yes, a utility inspector - don't get me started...yes, of
course, it was in NY).

Breaker retainers are a holdover from a time when load centers didn't have
the covers they have now. The new covers hold breakers in place so they
won't pop out. If you take that cover off, you could conceivably end up with
a breaker loose from the bus bar and in your hand. That is when your
argument comes into play. If that breaker were backfed by a generator or
other such electrical source you would have a handful of hot breaker - not
good. But with selling PV systems, inverters have been designed and tested
to UL1741, which requires that as soon as utility power is interrupted, the
inverter selling shuts down. So as soon as the breaker comes loose from the
busbar, it is no longer backfed and no longer hot. No safety problem, no
need for a retainer kit.

When we had this issue with the utility inspector, John Wiles went to bat
for me - with the utility and with NFPA. Unfortunately we lost. Remember
that the local authority having jurisdiction calls the shots. If the
arguments above just don't convince your inspector, you have two choices.
One is to replace that old Murray load center with something new (for which
retainer kits are available). This is probably not a bad idea but it is
probably an expense the customer was not prepared for and may be reluctant
to pay for.

The other alternative is what we ended up doing. Inside the Murray load
center we tapped the service wires feeding it (removed short section of
insulation from each service wire, installed split bolts and attached tap
conductors, and taped everything so it was well insulated - wrapping tape
covered with electrical tape .... you can also get plastic covers for split
bolts - a good idea). We ran the tap conductors to a very small service
rated Square D load center (for which retainer kits are available). That
small service rated load center must be very close to the tap location - we
mounted our load center right to the Murray and ran the conductors thru a
chase nipple. This met the NEC tap rules - I won't get into them here. The
point of interconnection for the PV system was then moved from the Murray
load center to the small service rated load center and a retainer kit was
installed. This is significantly less expensive than changing out the whole
Murray load center and satisfied the utility inspector.

Good luck!

E. H. Roy
Solar Works Inc.
64 Main Street
Montpelier, VT 05602
802 223-7804 x306
ehroy at solar-works.com


-----Original Message-----
From: Vince McClellan [mailto:mail at solarenergydesign.com]
Sent: Friday, September 05, 2003 2:00 AM
To: RE-wrenches at topica.com
Subject: RE; Breaker hold down kit [RE-wrenches]







I was wondering if anyone on the wrenches list might know where I can find a
hold
down kit for a Murry 15 amp 2 pole circuit breaker as required in NEC
article
408.16 F.
I have tried all my local sources and the only thing I could find was a
small
plastic
clip that only works for breakers over 70 amps. My inspector wants to see
any
back fed circuit breaker such as with a grid tie PV system held in place
.
It seems to me that NEC article 408.16 F was not written with grid tie
inverters
in mind because as soon as you disconnect the circuit breaker the inverter
stops
powering the breaker anyway.

Thanks

Vince McClellan

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