What year did...

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72gs455

Member
Location
Minnesota
What year did THHN 1st come out?

Here's why,
Last week excavators were digging for a foundation and found an abandoned steam station/ vault. Inside the mass was all the dead steam pipes and full of asbestos. While abating this week we notice some IMC that has some #4 THHN in it. The excavator unknowingly pulled and broke the pipe exposing the wires.

Steam hasn't been used at the site for 30 years.

I spent most of last week meeting with the city, power company and locators who all say it isn't theirs and was not supposed to be there.

I'm just trying to figure out the earliest time the wires could have been put in there.
I've been at the site for 16 years and never knew it was there...
 

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
What year did THHN 1st come out?

Here's why,
Last week excavators were digging for a foundation and found an abandoned steam station/ vault. Inside the mass was all the dead steam pipes and full of asbestos. While abating this week we notice some IMC that has some #4 THHN in it. The excavator unknowingly pulled and broke the pipe exposing the wires.

Steam hasn't been used at the site for 30 years.

I spent most of last week meeting with the city, power company and locators who all say it isn't theirs and was not supposed to be there.

I'm just trying to figure out the earliest time the wires could have been put in there.
I've been at the site for 16 years and never knew it was there...

I seem to recall that TW and THW was pretty much the norm until about the mid 70's. I don't recall THHN until about that time. But gee, that was almost 40 years ago.
 

ptonsparky

Senior Member
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
Electrical Contractor
I seem to recall that TW and THW was pretty much the norm until about the mid 70's. I don't recall THHN until about that time. But gee, that was almost 40 years ago.
I think that is about right. I can vaguely remember asking the supply house to bring some in for a gas station we were working on. They had thw and did not want to bring in that new s..tuff.
 
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