Multi-Contact parallel connectors [RE-wrenches]

Sun May 19 22:34:26 PDT 2002

John and wrenches,

Here is the post that never made it to the list:

Ryan,

I find that a smooth glass of wine works well when trying to ponder the
stranger things in PV. Just a little clarification for those who might have
misinterpreted my statements as having come on strong with the MC issue. The
problem is not the MC connector, nor is it the idea of developing a
paralleling cable to assist in wiring an array. The problem as I see it is
the possibility of some misapplying the connector in the field and trying to
parallel multiple strings of crystalline modules into a battery-based or
some inverter that could be a source of backfed current. Currently no
crystalline module on the market can handle that situation.

I can think of the one case in my Brain Teaser message where a harness that
could combine two or three strings together would be a good idea. However, I
know that I would spend the next three years of my life training installers
to only use this connector when connecting SP75 modules to a SunnyBoy system
and don't do it when connecting them to a Xantrex Sun-Tie, or whatever.

It complicates life for the installer/designer which is why I'm so stuck on
fully engineered system packages. We are starting to hear stories about
installers connecting 1000 Volts to SunnyBoys by accident, finding all kinds
of new ways to connect 600 volts improperly, and it scares the heck out of
me. I think there is far too little manufacturer's training on this
equipment and far too few engineered system packages.

I know most of the wrenches design their own systems, but how do people feel
about the newbees designing systems? How about wrenches with 600 Volts--we
talked about this over a year ago on the list and there was a lot of
well-deserved apprehension--I'm still worried.

Bill.

-----Original Message-----
From: jberdner at sma-america.com [mailto:jberdner at sma-america.com]
Sent: Sunday, May 19, 2002 6:43 AM
To: RE-wrenches at topica.com
Subject: RE: Multi-Contact parallel connectors [RE-wrenches]

Bill:

I do not understand why you say this assembly can not ever be UL Listed.
You can certainly make code approved, parallel connections with a number
of UL Listed Products.
Ilsco power distribution blocks come to mind for one.
Several other companies make UL recognized (RU) terminal blocks as well
but I am pretty sure the Ilsco's are UL Listed.
Listing versus RU is a big deal for 508A shops and when I was at Pulse
we had to have the Gould blocks tested by UL so we could use them in our
508A combiner boxes.  This testing was required because they were only
RU not UL Listed.  Split bolts, wire nuts, etc. also qualify as ways to
make parallel connections.  Over current protection does not necessarily
have to be included in a product for it to be Listed.

Also, I think the assumption that there are few places where this
product can be used is incorrect.  They can be used with most
crystalline modules and Sunny Boys for example.  They could also be used
in conjunction with inline fuse holders with any modules and any
inverter or battery combination.  Some modules have a high UL series
fuse rating compared to their Isc rating. In that case you can certainly
make a parallel connection without any over current device.  I agree
that this is usually higher voltage thin film but I think it is better
to do the calculation than to make a untrue blanket statement that a
parallel connection is strictly prohibited.

IMHO, parallel connections always add cost and complexity to a system
but there is nothing in the code that prohibits parallel connections.

One other thing to consider: Once you make a parallel connection you
have created a PV output circuit on the side away from the modules. Now
you have to consider the code requirements for that as well.  Some of
the exceptions the code allows for PV source circuits (one series
string) do not apply to output circuits (more than one series string).

If you have any questions, or if I can be of further assistance, please
do not hesitate to contact me.

Best Regards,

John Berdner
Phone: 530.273.45595
Fax: 530.274.7271

-----Original Message-----
From: Bill Brooks [mailto:billb at endecon.com]
Sent: Friday, May 17, 2002 11:57 AM
To: RE-wrenches at topica.com
Cc: Chuck Whitaker
Subject: RE: Multi-Contact parallel connectors [RE-wrenches]

Ryan,

This is precisely why that assembly is not, nor ever can be, a UL-listed
item. It could be a UL-recognized item that becomes part of a fully
UL-listed system package, but that is a very different situation. There
are
a few places where that assembly can be used in a code-approved fashion
and
will not void the UL listing of the modules (max series fuse rating for
amorphous silicon modules). But in most applications (crystalline
silicon) a
parallel connector is absolutely prohibited.

Bill.

-----Original Message-----
From: Ryan Mayfield [mailto:ryan at energyoutfitters.com]
Sent: Friday, May 17, 2002 7:45 AM
To: RE-wrenches at topica.com
Subject: Multi-Contact parallel connectors [RE-wrenches]

Wrenches,

I have a sample from Multi-Contact of their "branch plugs and sockets"
for
parallel connections of modules but there is no UL listing on them. I am
hesitant to use a non listed product and was curious what others are
doing
to get around this problem. Do you only bring down conductors off series
connected panels? Is there another product out there that has a listing
for
parallel connections? Thanks in advance.

Ryan

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