[RE-wrenches] Inverter "Phasing" on a single phase system

I have a question on inverter "phasing". By that, I mean connecting multiple 240 volt inverters to a common single phase sub panel or service panel and the need (or not) of making sure that L1 -L2 correspond on each inverter to the L1 - L2 buss bar in the panel. I recall issues in the early day

Re: [RE-wrenches] Rooftop wiring methods between multiple subarrays

August - we've been using 1/2" emt between arrays with plastic bushings to protect wires and a dual "minerallac" clamps ( http://minerallac.thomasnet.com/viewitems/pipe-fasteners/ll-categories-cully-pipe-fasteners-conduit-hangers?&bc=100|1006|1281&forward=1) to tie the conduits to the riser on t

[RE-wrenches] SW DC250 and conduit boxes

Colleagues: I have acquired a few SW conduit boxes and DC disconnects with all the trimmings that I'd like to get out of my shop. Contact me off list if you are interested. William Miller Please note new e-mail address and domain: William Miller Miller Solar Voice :805-438-5600 Fax: 8

Re: [RE-wrenches] Rooftop wiring methods between multiple subarrays

August and Max, If all you are doing in supporting the conductors, PVC conduit is sufficient with protective bushings on each end. Once you go to EMT, then grounding bushings must be installed at both ends and the EGC needs to pick up those bushings. More expensive and time consuming, but it

Re: [RE-wrenches] Rooftop wiring methods between multiple subarrays

August: I suggest the use of EMT with proper fittings to protect high voltage, high amperage DC Wiring on rooftops. Sure it is time consuming, but high quality, reliable craftsmanship will always be thus. William Miller At 11:07 AM 10/8/2009, you wrote: Hi Wrenches, I'm looking for

Re: [RE-wrenches] Rooftop wiring methods between multiple subarrays

Except for coastal installations where EMT is NOT recommended outdoors, PVC browns out and warps, and we should therefore use product X??? R. Walters r...@solarray.com Solar Engineer On Oct 9, 2009, at 11:38 AM, William Miller wrote: August: I suggest the use of EMT with proper f

Re: [RE-wrenches] Bare copper in EMT?

This link to galvanic compatibility is puzzling to me, it indicates that you should not connect copper wire to a gold plated terminal, or tin/lead solder on copper or connect a copper wire to a AL lug. However, all of these combo's are commonly done and most AL lugs are listed and rated for CU.

Re: [RE-wrenches] Rooftop wiring methods between multiple subarrays

Ray: Good question. We do use PVC in coastal zones to avoid corrosion. We try to keep it in the shade, paint it where exposed to UV and support it in close intervals. William At 10:57 AM 10/9/2009, you wrote: Except for coastal installations where EMT is NOT recommended outdoors, P

Re: [RE-wrenches] Rooftop wiring methods between multiple subarrays

All - PVC doesn't hold up well in the Bay Area - Here's a photo of some ~4 year old PVC browned PVC from Marin County: [cid:image002.jpg@01CA48DF.F8EAE150] You can see that the straps melted resulting in the conduit sliding down. Thank goodness we didn't install this. PCV seems like a good op

[RE-wrenches] PVC

August: As discussed, PVC is sometimes the best solution in a corrosive environment. I would never recommend supporting PVC as depicted in the photos. Shooting a screw through comp roofing is questionable at best. Better methods of installing PVC are available, including better straps and

Re: [RE-wrenches] Rooftop wiring methods between multiple subarrays

Thanks August... these images of PVC strapped to the roof, with a joint totally failing after only 4 years, are a great reminder to follow the code (some of this is new for 2008): NEC 352.20 (fasten PVC such that movement from thermal effects is permitted) NEC 352.44 (use expansion fittings to com

Re: [RE-wrenches] Rooftop wiring methods between multiple subarrays

August, Home Depot now sells bonding bushings for EMT down to ½”, which should solve the availability issue. I was very surprised to see them last trip to the HD money pit. Bill. ___ List sponsored by Home Power magazine List Address: RE-wrenche

Re: [RE-wrenches] Rooftop wiring methods between multiple subarrays

Hey Folks, I don't want to dicourage anyone from doing good work that meets or exceeds Code requirements. But I am a little quizzical about the how we all seem to be ignoring what the Code actual says about this. "250.97 Bonding for Over 250V Volts Exception: Where oversized, concentric,

Re: [RE-wrenches] Rooftop wiring methods between multiple subarrays

Mark, Although this exception is allowed, I think it is bad practice in the field. We will probably see the NEC revoke this exception within the next few cycles, and it may be revoked for PV systems much sooner. Relying on box connections to carry the low fault currents inherent in PV systems i

Re: [RE-wrenches] Rooftop wiring methods between multiple subarrays

EMT needs to be "pickled" with vinegar or acid, to get the paint to hold. I love it for inland work, but near the ocean, it'll rust through in 5 years. I'm not sure how much more time paint would buy you. Anybody use other plastic materials HDPE? Supposed to not have the expansion problems o

Re: [RE-wrenches] Rooftop wiring methods between multiple subarrays

Colleagues: I think the correct answer is: there are no short cuts to good workmanship. It requires intelligent design, a judicious selection of materials and careful installation. EMT is appropriate in low corrosion environments, PVC if you can control UV damage and accommodate expansion.