We have a conduit that has water standing in it that can not drain. Is this a problem as far as failures, code, or UL? NEC says that a wet location is one such as a car wash that is subject to saturation with water. I have called two wire companies and did not get an exact answer other than this is not a recommended use.
THWN WIRE AND WATER
- Thread starter nvcape
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Re: THWN WIRE AND WATER
I believe the "W" in "THWN" stands for a wet location rating. Also, the interior of conduits conduits ran in a wet location are also considered a wet location. However, if I remember right, THWN is only rated for 60 degree C use in a wet location. Thus, its ampacity may be somewhat less than it would be for a dry location.
That said, also see 230.53: "...raceways enclosing service entrance conductors shall be raintight and arranged to drain." Even if these aren't service entrance conductors, if the conduit fills up to the point that water runs into the electrical equipment, then you will have problems.
Steve
I believe the "W" in "THWN" stands for a wet location rating. Also, the interior of conduits conduits ran in a wet location are also considered a wet location. However, if I remember right, THWN is only rated for 60 degree C use in a wet location. Thus, its ampacity may be somewhat less than it would be for a dry location.
That said, also see 230.53: "...raceways enclosing service entrance conductors shall be raintight and arranged to drain." Even if these aren't service entrance conductors, if the conduit fills up to the point that water runs into the electrical equipment, then you will have problems.
Steve
- Location
- Massachusetts
Re: THWN WIRE AND WATER
Any raceway or enclosure underground is a wet location and requires the use of a "W" conductor.
THWN, RHW, XHHW etc.
THHN is usually also THWN, when used as THHN it is 90 C and when used as THWN it is 75 C.
In the area I am in almost all underground raceways are full or have sections that are full of water.
We ignore it, do not damage the insulation during installation and it will work fine under water.
It may not be recommended but it seems to be inescapable around here.
Any raceway or enclosure underground is a wet location and requires the use of a "W" conductor.
THWN, RHW, XHHW etc.
THHN is usually also THWN, when used as THHN it is 90 C and when used as THWN it is 75 C.
In the area I am in almost all underground raceways are full or have sections that are full of water.
We ignore it, do not damage the insulation during installation and it will work fine under water.
It may not be recommended but it seems to be inescapable around here.
Re: THWN WIRE AND WATER
So I was somewhat right about THWN not having the same ampacity in a wet location as a dry location, but I was wrong about which rating applies. Thanks for the correction Bob.
Somewhere (I don't have a clue where) I got the impression that the W is for "wet location", and the H if for "high temp." A conductor with no H has to be used with the 60 deg. column, one with a single H can use the 75 deg. column, and two H's lets one use the 90 deg. column (ignoring terminations). Does this sound right?
Steve
So I was somewhat right about THWN not having the same ampacity in a wet location as a dry location, but I was wrong about which rating applies. Thanks for the correction Bob.
Somewhere (I don't have a clue where) I got the impression that the W is for "wet location", and the H if for "high temp." A conductor with no H has to be used with the 60 deg. column, one with a single H can use the 75 deg. column, and two H's lets one use the 90 deg. column (ignoring terminations). Does this sound right?
Steve
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