[RE-wrenches] signage for remote External Disconnect Switches

Wed Jan 14 10:23:13 PST 2009

Thanks Allan!  I will poke around that website and maybe bother Frank if I
get desperate.

I have been in discussion with this utility about the necessity (or lack
thereof) of this switch.  In fact I've sent them that very document as well
as the PG&E explanation of why they do not require the switch (
http://www.pge.com/b2b/newgenerator/solarwindgenerators/disconnectswitches/)
but to no avail.  I must say, the engineer who seems to run the show over
there is very committed and makes a cogent argument (see below).  Like
Brian, my understanding is that these switches don't get used 99% of the
time when linesmen are working during a power outage because either a) they
pull meters or b) they just don't bother finding the solar homes in the
first place - they just test their line voltages where they're working.
That argument, however, holds no sway with this particular utility official.

Any other documentation out there of utilities that allow a label, map or
plaque describing the location of a remote External Disconnect Switch?  I
just can't stand the idea of a crew spending a whole day or maybe more just
moving this freaking disconnect...

Andrew;

Thank you for your e-mail.  I hope you find photovoltaic installations
interesting and exciting.  It is a great industry and great way to help with
renewable energy.  The requirement for the disconnecting means is a safety
requirement and should not create any additional burden since even a
residential water heater is required to have disconnecting means.  The
requirement for the readily accessible disconnecting means *is* a
requirement of the NEC and *is* intended to comply with the OSHA electric
utility work practice requirement in 1910.269 to be able to isolate a source
of energy.  The only difference between this disconnecting means and a water
heater is that the location must be readily accessible to those "workers"
who need to use it.  The ability to isolate and "lockout / tagout" a source
of energy is a basic safety philosophy of OSHA 1910.147 for workers.  This
basic philosophy is worked into Allegheny Power's employees work practices
as required by law.

I appreciate your discussion.  I know this is controversial issue and one
that has a lot of discussion.  I must say that I don't agree with the NREL
report nor does the majority of the electric utility industry agree with it.
 Also, when pressed, Underwriters Laboratory does not agree with eliminating
the disconnecting means.  Let me explain.  The electric utility industry
(not just Allegheny Power) is planning on directly addressing the points
made in this report.  We have also been in contact with representatives of
PG&E to explain the reasons for disconnecting means for interconnected
generation.  However, electrical installations in California are covered by
the California Electrical Code enforced by California Building Standards
rather than the National Electrical Code.  These requirements may be a
little different, but are typically based on the NEC.  I also know that the
PG&E "Codes and Standards" guy recently retired and they may not realize
they are not in compliance.

Did you know that pulling an electric utility meter under load is unsafe for
the worker and further will not de-energize all services?  Please do not
encourage anyone to do this practice.

Did you know that according to UL engineers (Timothy P. Zgonena and John R.
Kovacik) that an inverter tested/certified to UL-1741 as Utility Interactive
(I.e. UL 1741 Listed), may not always cease to energize the utility supply
wiring under all failure modes/mechanisms?  (Timothy P. Zgonena is the
author of UL 1741 and made this point to the representatives of the
electrical industry during the discussion regarding Article 690, 692, and
Article 705 for the National Electrical Code and interconnected generation.)

Because UL1741 pre-certified inverters only have to cease to energize a
de-energized line rather than "automatically disconnect" this feature makes
the requirement for a readily accessible manual disconnecting means
necessary because, UL cannot guarantee that the inverter will always work in
all situations.  This is also a provision of IEEE 1547 which is the parent
standard for interconnection of distributed generation.

If everything worked properly all of the time, the disconnecting means would
not be required.  However, since no one can guarantee that everything will
always work properly, the disconnecting means is required.  In the PG&E
case, they have been lucky that the equipment has worked as it was
originally designed.  After all, if we never had short circuits and ground
faults, fuses and circuit breakers would not be needed either.

Have a great day.  I hope this information is useful.

Tim

On Wed, Jan 14, 2009 at 2:02 AM, Allan Sindelar <
allan at positiveenergysolar.com> wrote:

>  Peter,
> I'd like to take issue with one point you make. The EDS is a utility
> requirement only, and is not required by Code. The breaker (or if it's a
> line tap, the adjacent fused disconnect) serves the full function of the
> Code-required disconnect and overcurrent protection. So keep the AHJ out of
> this issue, as that only gives the utility a greater illusion of legitimacy,
> and makes your own job harder. It seems to me that this is a utility issue
> only, and should be treated as such.
>
> Andrew,
> PNM in New Mexico has required EDS's (here they're called Customer
> Generation Disconnects, or CGDs), but they're optionally exempt under 10kW
> per new state regs. They allow it to be located elsewhere if a plaque and
> map are at the meter. Their website has changed re PV, and I can't find a
> link to send you. Frank at PNM may be able to help, although he's very busy
> these days: 505 362-7736.
>
> Your better approach is to defend the lack of need for the EDS. The
> utility won't budge, but if they see it's unnecessary, the location might
> then be flexible. See http://www.nrel.gov/docs/fy08osti/42675.pdf for an
> NREL report you can use.
>
> Allan at Positive Energy
>
>  -----Original Message-----
> *From:* re-wrenches-bounces at lists.re-wrenches.org [mailto:
> re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of *ASAP POWER! 2
> *Sent:* Tuesday, January 13, 2009 1:34 PM
> *To:* 'RE-wrenches'
> *Subject:* Re: [RE-wrenches] signage for remote External Disconnect
> Switches
>
> Andrew,
> Agree with purposes 1), 2).   You'll have to continue patiently educating
> both AHJ's and utilities meanwhile.  Most likely you would have to show
> the AHJ documentation of the utility's allowed variance.   Request a
> variance with a formal letter and fax it to them.   Show a complete site
> diagram showing a line of sight from subpanel'd EDS location to the meter
> location if you can.  If you cannot, show on diagram distance and location
> of point to where you can show a line of sight not through a structure.  Let
> them know the diagram will be an engraved or raised letter placard at proper
> letter size to be placed at the EDS location.
>
> Peter D.
>
>  ------------------------------
> *From:* re-wrenches-bounces at lists.re-wrenches.org [mailto:
> re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of *Andrew Truitt
> *Sent:* Tuesday, January 13, 2009 11:12 AM
> *To:* RE-wrenches
> *Subject:* [RE-wrenches] signage for remote External Disconnect Switches
>
>
>
>
>> I have come to a conclusion:  Utility companies serve two (2) purposes: 1)
>> To safely and profitably distribute electrical power and 2) To drive PV
>> integrators insane.
>>
>> The particular utility of which I speak, Allegheny Power, was responsible
>> for convincing the Maryland PUC for requiring External Disconnect Switches
>> on PV installs if they are to be eligible for REC generation.  Now they have
>> finally gotten around to inspecting a system we installed a year ago where
>> the EDS was located on the opposite side of the house from the meter (we
>> made our interconnection at a sub-panel) and they are requiring us to move
>> it back to the meter location (or install a 200A external service
>> disconnect).
>>
>> Does anyone know of any documentation from a utility or AHJ that accepts a
>> weatherproof label (or plack) on the meter indicating the location of the
>> EDS when it is not convienient for the meter and EDS to be co-located?
>>
>>
>> Andrew Truitt
>> Standard Solar Inc.
>>
>>
>>
>> --
>> "Don't get me wrong: I love nuclear energy! It's just that I prefer fusion
>> to fission. And it just so happens that there's an enormous fusion reactor
>> safely banked a few million miles from us. It delivers more than we could
>> ever use in just about 8 minutes. And it's wireless!"
>>
>> ~William McDonough
>>
>>
>
>
>
>
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-- 
"Don't get me wrong: I love nuclear energy! It's just that I prefer fusion
to fission. And it just so happens that there's an enormous fusion reactor
safely banked a few million miles from us. It delivers more than we could
ever use in just about 8 minutes. And it's wireless!"

~William McDonough
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