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I am attempting to "verify" that a 14/3 extension cord is double insulated by means of a label or marking. It is indeed double insulated because it is severed at one end and it is apparent by visual inspection. However, do any of the markings on the jacket indicate this?

(UL) C(UL) SJTW E232611 3/C 14AWG 300V VW-1 105C WATER RESISTANT CSA SJTW 205585 3/C FT2 APOLLO

The cable in question.

JYelton
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earl
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    I don't think I've seen the term "Double Insulated" used with regard to extension cords. However, STJW cable do have two layers of insulation - the individual wires are insulated, then twisted together and covered with an outer insulation. The GFCI housing might qualify for a "Double Insulated" marking. – Peter Bennett Jul 06 '23 at 21:53
  • Usually "Double Insulated" applies to a Class II appliance that has no ground pin. The depicted device DOES have ground connection. – Whit3rd Jul 07 '23 at 05:18

1 Answers1

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   (UL) c(UL) SJTW

Those indicate that the cable conforms to the US and Canada standards for SJTW insulation type for cordage. Not only does the manufacturer claim this, but an independent testing lab (namely, Underwriter's Laboratories) certifies it and surveils production to assure it remains so.

"Double-insulated" is an appliance certification which permits it to delete the ground wire. That doesn't jibe with this /3 cordage, which has a ground wire (that being the 3rd wire); cordage counts every wire unlike in-wall cables). I don't believe UL will allow a maker to misuse the green wire as a hot phase. I have never heard of a 120/240V split-phase appliance that deleted the ground wire by double-insulating.

Harper - Reinstate Monica
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