Hello again pfb1769,

OK I think I know what is going on and I completely agree with ErikMacs opinion directly above.

SJTW extension cord is a PVC jacketed, general purpose heavy-duty electrical cable suitable for outdoor use as it resists deterioration from ultra-violet radiation. The copper conductors are stranded and insulated with PVC and these legs are in turn stranded, often with polypropylene strand fillers, to make the core round before jacketing.

There are of course UL and CSA standards for these products and all companies must meet these basic standards. Saying that however, the cords business is very competitive and each manufacturer will continually be looking for ways to reduce their material costs. One way of doing this is to formulate and manufacture their own PVC compounds and thus each proprietary PVC compound will have slightly different mechanical properties. Other ways of reducing costs include the use of the longest allowable copper conductor stranding lays and leg stranding lays. Some companies may also extrude tighter jackets (over the separator covered core) than others in an attempt to minimize the overall cord diameter but maintain the minimum jacket thickness.

I expect the overall result of these individual company efforts is what you are experiencing with one particular cord manufacturer.

I also expect that these cords are being hand coiled and uncoiled daily in service at your locations and this leads to accidental twisting of the cord. (Think of this like dereeling a cord by pulling it sideways over the flange of the reel instead of properly unwinding it.) After a period of time, many, many twists are inadvertently applied to the cord and that is what I believe your photographs show.

At home I always keep my long extension cords (Such as a 250 foot, 3 conductor #10 and a 500 foot, 3 conductor #12) on reels and small, portable pay-offs to ensure that twists are not accidentally applied to the cords but this is probably not practical for your applications.

I hope that clarifies the present situation for you.

The bottom line is that the accidental twists are in all of your cords but some manufacturers' cords kink more readily than others.

My advice to you is to locate a cord manufacturer whose product gives you the best possible performance at some reasonable price and stay with that manufacturer.

Regards
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com
519 641-3212

Peter,

How are you. I think your "coiling" theory is probably right on. I have a cord that that happeend to. I also think that there may be somthing to the thickness or the jacket as the one that seems "different" is more of a problem.
By the way what does one do with a 250' or 500' extension cord?

spectre

He he,

Hi there Richard,

You would be surprised how handy these long extension cords can be. An example? Occasionally we have had block parties where we needed to get power out to a flatbed holding a band's amplifiers, microphones and such. Very easy to feed the power out from one or two garages.

You know how it is, "When in the business, one seems to end up with big extension cords for some reason or another." Unlikely you can buy those at the local hardware store

Cheers

Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com
519 641-3212