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Joined: Mar 2001
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Tom, characteristics not withstanding SE is not UL listed for underground use.
Unless you have some info that says otherwise.
Bob Bob Is THWN listed for use underground? If not then why do we use it in underground conduit. I believe that any conductor or cable that is suitable for use in wet locations is suitable for use in conduit outdoors. I fail to see how it makes any difference that the conduit may be partially, substantially or entirely underground. If we were talking about direct burial I could see a possibility of there being a problem. -- Tom H
Tom Horne
"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison
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I will post the UL info in it's context and you can decide if UL is silent on this. I will also post some handbook opinion and some NEC definitions. 2003 UL White White Book. SERVICE CABLE (TXKT) SERVICE ENTRANCE CABLE (TYLZ) GENERAL
This category covers service entrance cable designated Type SE and Type USE for use in accordance with Article 338 of NFPA 70, ‘‘National Electrical Code’’ (NEC).
Service entrance cable, rated 600 V, is Listed in sizes 14 AWG and larger for copper, and 12 AWG and larger for aluminum or copper-clad aluminum. Type SE cable contains Type RHW, RHW-2, XHHW, XHHW-2, THWN or THWN-2 conductors. Type USE cable contains conductors with insulation equivalent to RHW or XHHW. Type USE-2 contains insulation equivalent to RHW-2 or XHHW-2 and is rated 90°C wet or dry.
The cable is designated as follows:
Type SE — Indicates cable for aboveground installation. Both the individual insulated conductors and the outer jacket or finish of Type SE are suitable for use where exposed to sun.
Types USE and USE-2 — Indicates cable for underground installation including direct burial in the earth. Cable in sizes 4/0 AWG and smaller and having all conductors insulated is suitable for all of the underground uses for which Type UF cable is permitted by the NEC. Types USE and USE-2 are not suitable for use in premises or aboveground except to terminate at the service equipment or metering equipment. Both the insulation and the outer covering, when used, on single and multiconductor Types USE and USE-2, are suitable for use where exposed to sun. Now honestly, don't you think it would say "Type SE — Indicates cable for aboveground or underground installation." if that was what the listing allowed? Here is some info from the 2002 NEC handbook following 338.1 Type SE, cable for aboveground installation. Both the individual insulated conductors and the outer jacket or finish of Type SE are suitable for use where exposed to sun.
Type USE or USE-2, cable for underground installation, including burial directly in the earth. Cable in sizes 4/0 AWG and smaller and having all conductors insulated is suitable for all of the underground uses for which Type UF cable is permitted by the Code. Types USE and USE-2 are not suitable for use in premises or above ground except to terminate at the service equipment or metering equipment. Both the insulation and the outer covering, when used on single and multiconductor Types USE and USE-2, are suitable for use where exposed to sun. Please note no mention of using SE underground. Here is 2002 NEC 338.2 338.2 Definitions. Service-Entrance Cable. A single conductor or multiconductor assembly provided with or without an overall covering, primarily used for services, and of the following types:
Type SE. Service-entrance cable having a flame-retardant, moisture-resistant covering.
Type USE. Service-entrance cable, identified for underground use, having a moisture-resistant covering, but not required to have a flame-retardant covering. Notice that the definition for type SE is missing the words "identified for underground use" that are present in the definition for type USE. I hope someone else will jump in here, I have a lot of respect for Tom's opinions he is a knowledgeable member here and perhaps there is something I am missing. Bob
Bob Badger Construction & Maintenance Electrician Massachusetts
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Tom I was typing while you where posting. Bob Is THWN listed for use underground? That is an interesting point. Can I ask a couple of questions Why use a cable if the raceway runs form point to point? Is it allowed to run SE cable in a complete raceway? Not just a short section for physical protection. The 2002 NEC did not allow NM cable in a complete raceway, there is a change in 2005 to allow this. Bob
Bob Badger Construction & Maintenance Electrician Massachusetts
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A wet location is defined in Article 100 as installations underground..... That tells me that if I run conduit underground, I need an insulation with a W in it's designation. The letter U in a conductor designation stands for underground. I buy SEU cable for my services, not SE cable. I therefore can run this cable underground in conduit. (assuming that cable desigantions are the same as conductor designations) Also, the conductors have a W in their designation. I cannot direct bury it, as it is not rated for direct burial. SER, on the other hand has no U in the cable designation, but it does have a W in the conductor designation. Bare aluminum can be installed in conduit in wet locations, and the conductors can also. To be technical, I suppose that I should strip off the outer cable covering for the underground sections. That doesn't make a lot of sense, however, and, as someone else noted, I would worry about the bare aluminum ground corroding away without that outer SER covering.
Earl
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Iwire asked: "Why use a cable if a raceway runs from point to point"?
The aluminum SER I saw stuffed into a 2" pvc pipe underground was installed in a pvc pipe that was only continuous from where it exited one building into an LB and entered the other building through another LB...the SER cable was unbroken from panel to panel and the PVC was used just for the underground section of the feeder...eliminating the need for a juction to change wiring methods.
I'm not saying it's OK...just an installation that I question?
When I 1st looked in article 338, I looked for the "Uses not permitted" part that I see in most other articles...maybe it needs to be added for 2008...
shortcircuit
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I agree with Bob, although I think there is a problem with SE and SER as far as the UL listings and NEC requirements. Both of these say directly that SE and SER are for above ground use, yet the jacket of SE / SER will (unlike NM) identify the conductors inside which is XHHW or XHHW-2. I don't know of anywhere in the NEC where THWN is specifically worded to be for "Above Ground Use" The conductors of SE / SER wrapped in a PVC jacket would seem to be fine in an underground conduit if the two aforementioned inteties would not specifically say for "Above Ground Use" This could be a conspiracy but there is no way around it. Roger
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tdhorne, I run 4 wire USE all the time, we call it trailer cable up here. Mostly for feeders to trailers from the pole. But I have to pose a question, what is the difference in terms of conditions, between the underground conduit and the side of the house the SE would be subject to? Lots of rain, snowload, and ice up my way, can't see how that would hurt the cable any less than being in the ground with the frost.
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I believe the only reason for the designation: "above ground installation" is UL only tested it for "above ground installation", as the manufacturer only paid them to test it for "above ground installation". The conductors in SE cables have XHHW insulation. XHHW insulation is OK to be installed in wet locations, and underground conduit is, by definition, a wet location.
Earl
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OK guys no where in my posts will you see that I say it will not work. The problem comes down to the listing, for whatever reason SER is only listed for above ground use. I agree it makes no sense but that is the situation. If you use a product outside it's listing you have a 110.3(B) violation. I sent out a number of emails asking questions about this thread and the responses I got all have the same basic opinion. SE(R) will work fine installed underground. SE(R) installed underground is presently a NEC violation. Bob [This message has been edited by iwire (edited 11-27-2004).]
Bob Badger Construction & Maintenance Electrician Massachusetts
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Here's the 2004 UL White Book: http://www.joetedesco.com/2004geninfo.pdf I have helped to create many Code Scholars, so now everyone can become a Code Scholar too! Have Fun!
Joe Tedesco, NEC Consultant
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