[RE-wrenches] 90 degree wire bends

[Nik Ponzio]

 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.


On Wed, Nov 16, 2011 at 11:01 PM, Darryl Thayer <daryl_solar at yahoo.com>wrote:

> I have seen the lightening damage at tight bends, but in my electrical
> career of 60+ years I have not seen any other
> problems.
> Darryl
>
> *From:* Ray Walters <ray at solarray.com>
> *To:* RE-wrenches <re-wrenches at lists.re-wrenches.org>
> *Sent:* Wednesday, November 16, 2011 12:11 PM
> *Subject:* Re: [RE-wrenches] 90 degree wire bends
>
>  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.
> Aside from all that, is there actually an increased impedance from a tight
> bend (like in plumbing)? I don't know.
> 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.
>
> Aloha,
>
> Ray
>
> On 11/16/2011 10:35 AM, Marco Mangelsdorf wrote:
>
>  Some electricians have great fun in making 90 degree wire bends to try
> and make their enclosure wiring look so purdy.
>
> 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)?
>
> Thanks,
> marco
>
>
>
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