[RE-wrenches] Chimneys Rigid vs EMT

[Bob-O Schultze]

Daryl,
The Romex is a pretty clear violation of 690.31. This and the Pasadena  
fiasco that Peter Parish speaks of illustrates a very common problem  
that we all have. When it comes to photovoltaics, most AHJs don't know  
their A....thority from a hole in the ground.
Bob-O

On Mar 6, 2009, at 11:27 AM, Darryl Thayer wrote:


no I have not, however I have seen where an AHJ has allowed romex from  
the array down to the inverter in the basement through the house, the  
array wire to a 3r disconnect on the roof and plastic from the disco  
to the building entrance in the attic. No metal conduit from the array  
to the inverter occurred.  your case the AHJ is over kill, in my case  
is clear under protection, because the DC from solar can arc without  
overcurrent protection helping at all.

Darryl


--- On Fri, 3/6/09, Peter Parrish <peter.parrish at calsolareng.com> wrote:

> From: Peter Parrish <peter.parrish at calsolareng.com>
> Subject: [RE-wrenches]  Chimneys Rigid vs EMT
> To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
> Date: Friday, March 6, 2009, 12:55 PM
> We have an interesting situation in the enclave of Pasadena,
> CA.
>
> (1) The Pasadena Building and Safety Department is
> requiring the use of
> rigid conduit (only) on any DC and AC runs for grid-tied PV
> systems. They
> specifically prohibit EMT, LFNC and LFMC. This requirement
> applies to any DC
> or AC runs on the roof, and it applies to any DC or AC runs
> on exterior
> walls.
>
> They do not require the use of rigid conduit on A/C
> equipment, lighting or
> any other piece of equipment requiring exterior-mounted
> conduit conveying
> electrical power.
>
> (2) They also disallow a rigid conduit run anywhere on the
> exterior surface
> of a chimney. Where a conduit run on an exterior wall
> encounters a chimney,
> they require that the conduit run follow the line where the
> chimney meets
> the wall/roof. This means up the wall, along the roof and
> back down the
> wall.
>
> Although I think (1) is overkill, I will comply this once
> and engage the AHJ
> before the next job we have in this town; I have graver
> reservations about
> (2). I have lived over 50 years in California and I have
> seen the results
> severe earthquakes can have on residential chimneys. If the
> chimney goes,
> the first place it happens is on the unsupported portion
> above the roof. The
> next place the chimney fails is the higher portion,
> attached to the building
> frame. I think I can remember just one case where a chimney
> failed within 3
> feet of the foundation, and in that case most of the rest
> of the structure
> failed. Consequently if a chimney fails, there will be
> hundreds of pounds of
> brick raining down on the rigid conduit where it runs along
> the chimney roof
> interface.
>
> I would argue that the safest place for a rigid conduit run
> would be around
> the chimney in the crawl space (if any) underneath the
> house, attached to
> floor joists. If that option is not available I would argue
> for a run around
> (and anchored to) the exterior chimney at about 2-3 feet
> above grade.
>
> Is item (2) essentially a B&S issue not addressed by
> the Fire Department?
>
> Has anyone encountered these sorts of requirements
> elsewhere?
>
> Comments?
>
> - Peter
>
> Peter T. Parrish, President
> California Solar Engineering, Inc.
> 820 Cynthia Ave., Los Angeles, CA 90065
> Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885
> CA Lic. 854779, NABCEP Cert. 031806-26
> peter.parrish at calsolareng.com
>
>
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