I had an off-grid customer report that their huge well pump surge caused an insulation melt-down at a tight bend in the wire. <br><br><br><div class="gmail_quote">On Wed, Nov 16, 2011 at 11:01 PM, Darryl Thayer <span dir="ltr"><<a href="mailto:daryl_solar@yahoo.com">daryl_solar@yahoo.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div><div style="color:#000;background-color:#fff;font-family:arial, helvetica, sans-serif;font-size:12pt"><div><span>I have seen the lightening damage at tight bends, but in my electrical career of 60+ years I have not seen any other</span></div>
<div><span>problems. </span></div><div><span>Darryl </span></div><div><br></div><div style="font-family:arial, helvetica, sans-serif;font-size:12pt"><div style="font-family:times new roman, new york, times, serif;font-size:12pt">
<font size="2" face="Arial"><div style="margin:5px 0px;padding:0px;border:1px solid rgb(204, 204, 204);min-height:0px;line-height:0;font-size:0px" readonly></div><b><span style="font-weight:bold">From:</span></b> Ray Walters <<a href="mailto:ray@solarray.com" target="_blank">ray@solarray.com</a>><br>
<b><span style="font-weight:bold">To:</span></b> RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org" target="_blank">re-wrenches@lists.re-wrenches.org</a>><br><b><span style="font-weight:bold">Sent:</span></b> Wednesday, November 16, 2011 12:11 PM<br>
<b><span style="font-weight:bold">Subject:</span></b> Re: [RE-wrenches] 90 degree wire bends<br></font><div><div></div><div class="h5"><br>
<div>
<div>
It seems that if the strands were stretched and therefore thinned,
that that would increase resistance, some. I think more importantly,
the insulation bunchs up and cracks, and is definitely
compromised. Also with strain hardening of copper, I'm sure some
strands could break internally with a tight enough bend. I've heard
at least for bare ground wires that lightning will jump off to the
case at tight bends, but I've never actually seen that. <br>
Aside from all that, is there actually an increased impedance from a
tight bend (like in plumbing)? I don't know. <br>
I've had to stop more than one journeyman from violating 300.34. I
just tell them the bends should look like the long sweeps in conduit
relative to the diameter of the wire: also purdy.<br>
<br>
Aloha,<br>
<br>
Ray<br>
<br>
On 11/16/2011 10:35 AM, Marco Mangelsdorf wrote:
<blockquote type="cite">
<div>
<div>Some electricians have great fun in making
90 degree wire
bends to try and make their enclosure wiring look so purdy.</div>
<div> </div>
<div>Given the importance of maintaining wiring
radiuses, this
can’t be a good idea, can it? Is the issue greater resistance
when the
wire is bent at a straight 90 degrees (or more)?</div>
<div> </div>
<div>Thanks,</div>
<div>marco</div>
<div> </div>
</div>
<br>
<fieldset></fieldset>
<br>
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