ECN Forum Forums General Topics of the Trade General Discussion Area messenger wire

I am installing 40' steel poles for security lighting. My dilemma is I cannot run the conductors underground because of the ground conditions. Obviously aerial is my only option. Problem is the span is about 125 to 150' between poles. I find no restrictions in the code pertaining to length of span, only height. That is my first question. Is their a distance maximum? Second, if their is no max requirement I plan to use messenger wire to connect the poles in order to support the triplex. Any suggestions or "bewares" that perhaps you or someone you know has run into. If I start adding poles just for support purposes, the cost will go up substantialy which I am trying to avoid.

First concern would be IF the 40' poles are capable of supporting the weight of the overhead wiring and messenger. You should check with the mfg (application engineering) before you get in too deep.

From experience, most manufacturers restrict the installation of banners, signs, etc.

Steel (preferably stainless) messenger, with insulators at each pole, and triplex (AL) attached with stainless bridles is the best way, although more costly.

John

Don't forget to factor in sag, wind loads, icing, etc.


Almost forgot: birds, also ;-)

[This message has been edited by ThinkGood (edited 09-13-2002).]

See the NEC Articles covering "Outside Branch Circuits and Feeders" and "Messenger Supported Wiring" for the answers to your questions.

Their is nothing in the article referring to "span maximum". The poles are rated for the application. Hubbel has no problem with it. Colleague of mine told me to make sure the manfctr supplies the thimble that way I am covered.

I believe that the answer to the question can be found here in the 2002 NEC:

225.1 Scope.

This article covers requirements for outside branch circuits and feeders run on or between buildings, structures, or poles on the premises; and electric equipment and wiring for the supply of utilization equipment that is located on or attached to the outside of buildings, structures, or poles.

FPN:For additional information on wiring over 600 volts, see ANSI C2-1997, National Electrical Safety Code.

225.6 Conductor Size and Support.

(A) Overhead Spans. Open individual conductors shall not be smaller than the following:

(1) For 600 volts, nominal, or less, 10 AWG copper or 8 AWG aluminum for spans up to 15 m (50 ft) in length and 8 AWG copper or 6 AWG aluminum for a longer span, unless supported by a messenger wire

[This message has been edited by Joe Tedesco (edited 09-13-2002).]

Another place to look for guidance is in a Linemans Handbook. You may have to go to the library to find one, but they are available.