Thread: Blue Romex with odd ground wire

Has anyone seen a light BLUE Romex thermoplastic conductor before? it has an odd, smaller gauge, insulated grounding conductor (almost looks like a speaker wire). Unfortunately I can't get to anyplace to see the TYPE __ printing on the wiring. See pic.

Similar Threads:

• Glowing wire nut
• Ground in crawlspace
• Disconnected Wire
• 2 Wire Load Side Fuse Panel
• Recalled Ladders for Above-Ground Pools

All the NM cables in there are blue colored, however, looking at the sides of the NM cables, they look to be other-than-blue, grayish in color.

Wondering what may have cause that, and when, during handling (installation)? What, why?

Have not seen NM cable with an insulated ground before - not that I can recall, anyway. The 'ground' looks to be white with a tracer, is it possible that that is three conductor without a ground? That would make some sense.

What year was the house built?

Hey Jerry.
The original part of the house is 1905 (knob & tube and all), but this panel is in a newer addition. Can't say when it, or this panel was added. I would tend to guess sometime in the 70's.

There are several of these "blue" colored conductors in the panel. Here is another pic showing the grounding bus bar. You can see that the grounding conductor is a smaller guage than the neutral. (of course you can also see how they have improperly twisted the grounds around each other).

I was wondering if this was some type of wiring normally used in some other application, not typically found in residential construction. Around here I find all kinds of wierd building materials and stuff (no electrical inspectors around until the late 80's, and no city inspectors until about 10 years ago).

that is old southwire type nm that had a reduced grounding conductor it has a green insulated grounding conductor that is 16 gauge and mostly had a blue outer covering.

Originally Posted by paul hardy

that is old southwire type nm that had a reduced grounding conductor it has a green insulated grounding conductor that is 16 gauge and mostly had a blue outer covering.

If that is 16 gauge, that puts the age of this particular stuff in the early or mid '60s. At least that would be true around here.

Some brands of early grounded NM wiring had a smaller gauge ground wire that was sheathed. Most of it I find has a light green sheathing over the ground wire.

Definitely mid to late 1960's. I have worked with that stuff when replacing old FPE panels on homes from that era.

The brand name escapes me, but I have seen this stuff, referred to as "builder's wire" on the box. It came in a blue and white box. The outer insulation was blue, the grounding conductor was one wire gauge smaller, and insulated. The last time I saw that kind of cable, in the box, was about 10 years ago, in somebody's garage.

I found this old post. I ran into something similar. House built 1969, but the Romex was white as usual, not blue, mentioned in earlier posts, as seen in second picture. Ground wire insulated in green sheathing, obviously smaller than other conductors. This must have been allowed back in the day. Why? The copper savings of using smaller gauge wire, not anticipating current flow on the ground wire??