Articulation of wiring problems [RE-wrenches]

[William Miller]

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Friends:

I visited a site yesterday for a service call on a system that I did not 
install.  I do a thorough inspection of all wiring.  I found several things 
that I know are wrong, but darn if I'm not having a little problem 
articulating why they are wrong.  I'd like to give a brief description of 
the problems, and if anyone out there can help me put in words why this is 
a problem, I'd be very grateful:

1. PV wiring:  40 SR100s on 5 Zomeworks trackers.  4 modules are wired in 
series and paralleled with another string of 4.  Positive and negative 
leads are fused.  I know this is wrong because:

a. there should not be fuses in the negative leads and can probably find 
the NEC citation.
b. If there are more than 2 or 3 strings, each string should be fused 
instead of each PAIR of strings and, thanks to John Bercener's paper, can 
prove that easily.  Below is a link to the wiring diagram:

http://www.mpandc.com/case_studies/Scott/PV.jpg



2. Charge controller wiring.  All strings are combined in positive and 
negative busses in the orchard.  Each buss is connected to a 1/0 lead that 
runs to the garage about 150 feet away.  In the garage, the 1/0s connect to 
two smaller busses.  From each buss, a #6 lead connects to each of three 
C40 charge controllers.  I know this is wrong because:

a. There is no disconnecting means for each charge controller input,
b. Each charge controller should be wired directly to the strings it is 
controlling,
c. Each controller is subject to all of the current produced by all PV 
modules, well in excess of the 40 amps rated for each controller.

Are there code passages related to a through c above?  the link above also 
shows this wiring.


3. Ac wiring.  The house has a 400 amp Cutler Hammer service.  The meter 
jaws had factory installed jumpers that fed a small buss in the customer 
side that has a 200 Amp breaker designed to feed a sub panel and also 
connect to a 200 amp breaker feeding breaker buss bars for branch 
circuits.  The installer removed the factory jumpers from the meter jaws 
and routed the meter output to a fused disconnect and then back to the 
meter cabinet.  Below is a link to a drawing of this wiring:

http://www.mpandc.com/case_studies/Scott/ACWiring.jpg

I know the above is wrong because:

a. The factory internal wiring has been modified, violating it's listing.
b. There is no longer any disconnecting means for the wiring to the fused 
disconnect,
c. It may violate the tap rule.

Anyone want to chime in on this scenario.

Thanks for your input.

William Miller



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