Flexible Cables: Important Safety Issue [RE-wrenches]

[Allan Sindelar]

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Wrenches,
Several years ago I offered to John Wiles to be a conduit for his messages
to get to the Wrenches list, as he is not set up as one. A couple of times a
year he'll ask me to forward a message. I don't censor it, and Michael has
never asked me to do it any differently. I don't always agree with him, but
I respect his role, and he is always helpful when I need to work out an idea
(even though sometimes the customer can't afford the solution).

Here's a little behind the scenes stuff that I think is worth sharing on
this issue. This started after I started forwarding the first responses back
to him:

John to me:
>>Thanks for the update-I expected there would be quite an uproar.
>>  I'll keep track of it by visiting the web site.
>>
> > Real electrical contractors pull these large cables all of the time
> > or use the flexible cables with appropriate terminals.

Me back to John:
>John,
>Your comment about real electrical contractors is bullshit, John, and I'm
>calling you on it. All Real PV contractors including us have installed many
>Trace DC175 and DC250 enclosures that come supplied with Heinemann GJ
>breakers with mechanical lugs. Those fall under your post as unacceptable,
>yet there isn't an appropriate terminal that is recommended in the
>manufacturer-supplied instructions of this ETL (not UL)-listed product.
>
>We carry a wide supply of listed crimp connectors and the crimpers to use
>them, and as far as I can figure, with the possible exception of a few SO
>cords, this GJ issue is the only exception to our use of fine-stranded
>cables with crimp lugs. But be careful about offhand comments like that; we
>real electricians don't take kindly to it.
>Allan

John replied at length:
>Allan:
I am not sure what you found offensive about this.  Please elaborate?
I work with licensed electricians (generally not PV installers-yet)
all over the country and for the most part they use standard
13-strand cables up to about 2/0 AWG.  After that they start
paralleling cables to increase ampacity.   In the big commercial
power jobs involving 10-100 MW generators, it is common to see 500
Kcmil 37 strand conductors being pulled and paralleled.

Lack of knowledge on the part of the installer or that of
Trace/Xantrex does not excuse them from complying with the law (in
this case the code where legislated into law).

Just because Xantrex, Heinemann or AirPax do not provide terminals
for use with the fine stranded conductors that the contractor might
wish to install does not imply any wrong doing on their part.  They
are complying with the standards as written.  The standards are set
up for the types of cables (the stiff ones) that have been used in
most applications for nearly 100 years.  The responsibility to match
the products properly lies on the user of their products.

Since I told many installers about fine stranded cables years ago in
a direct fax campaign and through Home Power Magazine, I feel the
need to ensure that those cables are being used correctly.

It is unfortunate that the wire bending spaces in most RE products
just barely meet the UL/NEC wire bending requirements.  In a few
cases like the C-40, MX 60, and SW4024/48 they don't meet the
requirements. In some cases this is mentioned in the manual as a
requirement to use a smaller conductor than the ampacity calculations
would dictate.

That is why a Square D H361 at 30 amps is nearly half the size of a
Xantrex DC 250 at 2 x 250 amps.

I too have used the 4/0 and 2/0 AWG fine stranded cables incorrectly
over the years and was just about to connect a Sunny Island SI 4248
with some very nice 2/0 AWG USE-2/RHW-2 fine stranded cables.
Instead I went with regular 2/0 AWG THHN.  I installed 2/0 THHN
through an LB and two 90° turns with only a few #$%^$#@ words and
only two bloody joints.  Monkey grease helped.

I have also been talking with Rob Cary who, as a battery guy, said
"About Time" to my e-mail.  He has had the same problem with the
large UPS installers, circuit breakers and other terminals, and the
fine stranded cables.  So PV guys are not unique.

Allan, as always, I appreciate your feedback.<

A day later, after I cooled off, I sent him:
>John,
I lashed out a little too harshly. I apologize for my colorful language and
harshness of tone--sorry.
Allan<

And received:
>No sweat.  Eudora showed only 3 chillies on your e-mail.  Sometimes I
get 4 chillies<

My own take--as we have proper lugs and crimpers too, the only place this
really affects our existing work is with the Xantrex DC175/250. So this
sounds like a relatively small issue being blown out of proportion. But I'll
add this, re:
>when one has been laboring away in this field for as long as
(ahem) many of us have, you very naturally arrive at certain conclusions
about the way things have developed over time and how they got that way. For
many of us these changes have not always seemed to be for the better or even
made sense, though many others actually have been very positive.<
I tend to do it the way it has always worked just like the rest of us, and I
must concede that it does me good to have someone rattling my cage about
these things from time to time. Sometimes I can realize that maybe there's a
better way than mine.

OK, gang, next post is --guess what -- a forward from John Wiles.

Allan at Positive Energy

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