Disconnects on Fronius [RE-wrenches]

[Mark Frye]

I tend to agree much more with Dan on this issue. Note also that the 
brand with the X also uses an integrated "DC Disconnect".

Once you have a fused combiner box, you essentially have an external 
disconnect.

In a small system with just a few strings I don't have a fused 
disconnect and do have to get to the MC connector which are also "no 
load" disconnecting means. I always build with plenty of space between 
the array and the roof deck and home run connectors are always easy to 
get at.

An electrician is a person who knows the hazards associated with working 
on electrical systems and knows how to protect themselves from those 
hazards.  PV systems have their own particular hazards which can be 
addressed with specific protective actions.

Just like any other aspect of electrical work, you shouldn't work on PV 
it if you don't know it. I think we should be focusing on disseminating 
appropriate safety measures for working on PV rather than putting a 
bunch of bells and whistles on methods that already have the basic 
protective elements available to the qualified individual.

Berkeley Solar Electric Systems


William Miller wrote:
> 
> Dan:
> 
> I have to say I think you and Fronius are way off-base on this issue.  
> You 
> are encouraging installers to install systems unsafely just to save 
> themselves a few dollars.  I presume this is to give Fronius some kind 
> of 
> market advantage.
> 
> Here's an analogy for you:  I could not install a roof-top air 
> conditioning 
> unit and have the disconnect for it at ground level.  The disconnect has 
> to 
> be within line of sight of the unit.  Human nature being what it is, 
> someone is going to remove a Fronius inverter and fail to get a ladder 
> and 
> climb up on the roof just to disconnect the DC feeder to the inverter.
> 
> If Fronius had remained silent on the issue, that would be one thing, 
> but 
> actively encouraging installers to disregard common safety practices is, 
> in 
> my professional opinion, unconscionable.
> 
> As I said, I like your product and I like your people.  I disagree 
> strongly, for safety reasons alone, on this one issue.
> 
> 
> Sincereley,
> 
> William Miller
> 
> 
> 
> 
> 
> At 12:16 PM 10/19/2006, Fortson Dan wrote:
> 
> >Hi William,
> >
> >I hope you are recovered from the SP-2006 event. I have read your 
> >comment 
> >on wrenches & will respond there as well. My stand on the Fronius 
> >disconnect & code compliance is somewhat more measured than Fronius 
> >techs 
> >in the past as I believe it's ultimately up to the inspector. I 
> >understand 
> >Mr. Wiles refuses to commit on the matter. The live wire issue is real & 
> >
> >not trivial though. In fact, in the training I just gave at SP2006, I 
> >emphasized to those in the class, who would likely be the ones 
> >disconnecting a unit from the wall, that it is neither safe nor 
> >advisable 
> >to do so while the wires are hot. I generally recommend pulling string 
> >fuses or disconnecting one connector in each string, then checking with 
> >a 
> >volt meter or on the Fronius display that DC voltage is, in fact, zero. 
> >This method ensures that there will not be live wires unattended for 
> >children to play with, etc.
> >
> >Your solution of using an external DC disconnect ensures safety but many 
> >
> >installers do not feel the trade-off is worth the investment. That's a 
> >personal decision which must be made by the installer.
> >
> >Hope to see you next year at the show,
> >
> >Dan Fortson
> >
> >Applications Engineer
> >
> >Fronius USA
> >
> >(810) 220-4414
> 
> 
> __________________________________________________________________
> William Miller
> Miller Power and Communications
> Voice :805-438-5600     Fax: 805-438-4607
> email: wrmiller at mpandc.com
> http://mpandc.com
> License No. C-10-773985
> _____________________________________________________________
> Check out our latest project at 
> http://mpandc.com/case_studies/pv_school/pv_school.html 
> --
> [Non-text portions of this message have been removed]
> 


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