William,

Not sure I understand how buried PV runs protected by touchsafe fuses in
combiner boxes at the array and GFCI protection at the inverters constitute a
fire hazard.
That's not saying I disagree with your disconnect here. I don't. If it was a 1kW
system, would you still install one? I would not.

Would not a deeper trench with properly located burial tape have been a good
call? If the array was installed and visible, maybe the excavation operator
would have thought to ask about underground utilities. 
They should have anyway. Would not common sense imply the operator would drop a
bucket of fill on any sign of arcing. Would they know to look for a disconnect
at the array in any case?

Common sense can be slippery.

Dick 
Solarwind Electric





--- You wrote:
Friends:

I am embarking on a 10 Kw ground mount grid-tie installation.  The client 
prepared for this installation some time ago by stubbing a PVC conduit 
underground towards the future location of the PV array.  Prior to 
beginning this job, an excavation contractor intercepted the empty conduit 
with a backhoe.

No harm was done because this conduit was empty.  Had this conduit been 
filled with PV feeders, it would have been very necessary to be able to 
disconnect the PV arrays, both for safety and to prevent a brush fire in 
our very dry climate.

The inverters will be located in a pump house about 130 feet from the PV 
arrays.  I would not normally put disconnects at the array and they are not 
required.  This scenario, however, has caused me to reconsider.  The design 
now calls for a disconnect at each row of modules.  I feel that it would 
not be prudent to delete this important safety item.

I wish there were a better selection of  compact, low profile disconnects 
suitable for a roof-top installation.  I have put external handle 
disconnects on roof but they look terrible.  I may specify touch-safe fuse 
holders inside of a Sola Deck for future comp roof jobs.  I am not sure 
what we will do with tile roofs.

It seems to me that every source of power should have a means of 
disconnection as close to the source as possible.  This is just common sense.

William Miller


Please note new e-mail address and domain:

William Miller
Miller Solar
Voice :805-438-5600
email: william@millersolar.com
http://millersolar.com
License No. C-10-773985
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