SO cord

Todays inspection on a commercial site had a lot of so or soj cord running through walls and this strange outlet you see below. I forgot what s.o stands for. Mark???



Hi Gary,

It’s actually SJO cable.

S = Service Grade (also means extra hard service when not followed by J, V, or P)
J = Hard Service
V = Vacuum cleaner cord (also light duty cable)
P = Parallel cord (also known as zip cord) – Always light duty
E = Thermoplastic Elastomer (UL/NEC designation ONLY)
O = Oil Resistant*
T = Thermoplastic
W = Outdoor-includes sunlight resistant jacket and wet location rated conductors (formerly “W-A”)
H = Heater cable
VW-1 = Flame retardant
FT2 = Flame retardant


Oops! Forgot this.

  • When only one “O” appears in a classification (i.e. SJEOW), only the outer jacket material is oil resistant. If two “O’s” are in the classification (i.e. SEOOW), the insulation covering the conductors and the outer jacket insulation are all oil resistant


Thank you Michael.

You’re very welcome. :wink:

Is Parallel cord and lamp cord the same thing?

Hi Doug,

In terms of it being named parallel cord yes. :wink:

There are different types of parallel cords and ratings these days.

An HPN parallel heater cable for instance is FT1-FT2 in fire ratings and can handle a higher current than standard parallel cord or lamp cord.

Most parallel cords have a ground and most lamp cords don’t.

Hope this helps,


Hi Michael. Thanks for those designations. Very useful information!


Regarding the outlet, it looks kinda like an ordinary duplex receptacle, albeit with the lower ground opening full of crud. Somehow the picture give me the impression that, if you were to grab the receptacle box, it would not be very firmly attached to the wall.

Thanks. Occasionally I run across homeowner installed wiring for everything from dishwashers to garbage disposals using “lamp” cord and always write it up as being completely wrong for the particular application. People will often use what they have lying around the house or garage and never give it another thought. Thank you again for some good clarification on the different cable designators.

Hi Doug,

You’re welcome.

I did notice that the connector on the left side is not approved for exterior use. It need to be a liquid type connector like on the right.


Here is what Mike is refering to:

**II. Installation
314.15 Damp, Wet, or Hazardous (Classified) Locations.
(A) Damp or Wet Locations. **In damp or wet locations,
boxes, conduit bodies, and fittings shall be placed or
equipped so as to prevent moisture from entering or accumulating
within the box, conduit body, or fitting. Boxes,
conduit bodies, and fittings installed in wet locations shall
be listed for use in wet locations.

lets also keep these in mind also…

**400.8 Uses Not Permitted. **Unless specifically permitted
in 400.7, flexible cords and cables shall not be used for the
(1) As a substitute for the fixed wiring of a structure
[FONT=Times-Roman]size=2 Where run through holes in walls, structural ceilings,
suspended ceilings, dropped ceilings, or floors
(3) Where run through doorways, windows, or similar
(4) Where attached to building surfaces
*Exception to (4): Flexible cord and cable shall be permitted
to be attached to building surfaces in accordance with the
provisions of 368.56(B)
*(5) Where concealed by walls, floors, or ceilings or located
above suspended or dropped ceilings
(6) Where installed in raceways, except as otherwise permitted
in this *Code
*(7) Where subject to physical damage

If it was exterior it should have had a WP cover, also the box may be a 1-7/8" box which I believe would only be allowed to have 1 conductor entering due to the CI capacity.