new wire for array wiring? [RE-wrenches]

[Dean T. Newberry]

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Hello Jeffery and William,
We also tiewrap the pigtails under the modules where they are 
"protected" from physical damage, and transition with a J box to a wire 
for the drop. The difference is we always use emt or rigid instead of 
PVC Sched 40 or 80 for the DC cover down to the DC disconnect. The 
reason is that we have reports from the field that the inverters supply 
significant Radio Frequency Interference on the DC leads from the roof, 
and we want to shield our neighbors from the RFI. We also tend to use 
only XHHW-2 for field wiring, it is rated for direct sunlight, and in 
the conduit. If that is what we have on the truck that's what will be 
used and it meets requirements for both conditions. I have gotten the 
building inspectors to look for and accept a grounded bushing for the 
transition from the J box to the roof as a method of maintining ground 
integrity from the array to the conduit. We use a conduit sealant to 
slow down the water as it gets into the piping. Another method is to put 
the bottom of the DC disconnect below the bottom of the inverter so any 
water that gets into the drop drains out of the disconnect which is not 
sealed instead of into the inverter which is sealed. ( I have drained a 
lot of water from inverters which were still operating)  We also 
invested in a crimper to add MC connectors to the  XHHW-2 instead of 
cutting and wirenutting to the pigtails. We bought it directly form 
Daniels for a little less than from MC.

There was an old thread on the RFI, maybe someone else has the relevant 
text.

cul deant

Jeffery Wolfe, Global Resource Options wrote:

> 
>William,
>
>While I understand and respect your opinion, no way am I going to push
>to go back to wiring each panel with wire and conduit. Lots of problems
>in that set up to after 20 years on a roof. Too many places for water to
>get into. Give me a potted JB any day, and proper installation
>techniques. I agree, 20 feet unprotected across a roof is not good. We
>bring the USE-2 right to the edge of the array, tie-wrapping it as we
>go, and into a single PVC JB at the array edge. At that point we
>transition cleanly to whatever we want, typically THHN in PVC conduit.
>(Yes, the THHN is cross-labeled as THWN-2, at least last time I looked.
>But try asking for THWN-2 and everyone looks at you cross-eyed around
>here.)
>
>And for those really weird set ups that everyone who does real wrenching
>runs into every once I a while, we've found that a pair of snips takes
>the MC's off the ends of the cable real fast, allowing us to wire
>straight into a field supplied junction box when required. Not often,
>but occasionally when tapping into an old off-grid array.
>
>Jeff Wolfe
>Global Resource Options
>800-374-4494
>  
>
-- 

Dean T. Newberry
Marketing and Sales

Quantum Energy Group
256 Applegate School Road
Applegate, Ca. 95703

Tel: 530 878-4585
Fax: 530 878-6685
Cel: 530 867-2392

deant at dcn.org
http://www.talbottsolar.com/
http://mjdsolar.com/

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