ECN Forum

SER cable in conduit

Posted By: master66

SER cable in conduit - 07/05/05 01:44 AM

I am pretty sure that it is not allowed but I can't find where it says that type SE or SER cable cannot be installed in conduit for a complete run of say...60 feet.

I have to inspect a job that my electrician wannabe brother-in-law did where I know that he installed two 200a subfeeds in a small garage in PVC conduit using SER cable (4/0).

Anyone I know would have used THHN and it would not be an issue but he doesn't know any better.

Help me justify failing the installation or tell me if I'm wrong.
Posted By: renosteinke

Re: SER cable in conduit - 07/05/05 02:06 AM

I have reviewed both the NEC and the UL "White Book." Neither specifically address the issue- it appears that no one considered it.
Type USE is severely limited in its' indoor applications, but there is no such limit on SE.

Since it is not specifically prohibited, I would say it is allowed- especially if there is a desire for additional mechanical protection.
However, I would consider the issue of de-rating, as is done with Romex. While there is no official temperature rating for the assembly (unlike Romex, which is 60 degrees), it seem reasonable to treat SE in a like manner.
Posted By: gfretwell

Re: SER cable in conduit - 07/05/05 03:06 AM

The most immediate issue would be wire fill. It is considered one conductor with the diameter of the maximum dimension so a pipe fills up fast.
Posted By: George Little

Re: SER cable in conduit - 07/05/05 03:23 AM

I looked in the '02 NEC at Article 352 Sect 352.22 and it seens to say no- SER installed in RNMC would not be a code compliant installation because SER is not specifically identified for use in a raceway. Some cables are identified as being acceptable when installed in a raceway: Fire alarm cable (760.54) NM cable for short sections (334.15 (B)) Class 2 & 3 cables (725.55(C)). I do not see that kind of wording for SER or SE cables.

Now if you go to the '05 code Article 352 Section 352.22 is worded diffeently and it might change things. Now why anyone would want to install a raceway system and then pull in SER or SE cable is beyond me. The chance of overfilling the raceway or damaging the cable is very high.
Posted By: George Little

Re: SER cable in conduit - 07/05/05 03:33 AM

I almost forgot- If this is an underground installation then the Listing for SE or SER cable would be violated since it is only listed for above ground.
Posted By: Elmer

Re: SER cable in conduit - 07/05/05 12:11 PM

I came across the same situation: SER in 21/2" pvc #80 outside od house. 50' run,2-90% and 1-LB then to meter main. Cable tech. drill a hole in the conduit and shorted out the feed. I told them that I needed to replace the conduit and install the correct cable (THHN). What you had was a violation. They said prove it. I opened up the code book and look & look, but could not find any thing to support my statement. It would seem that SER in such a run of pvc would be wrong. Maybe ampacity,number of conductors in conduit would play out in the code? Would that large of SER 200amp size bent in a LB a violation. That must have been someting to install. Or my last one was "not completing conduit run before installing cable". ????
Posted By: markp

Re: SER cable in conduit - 07/05/05 03:37 PM

George, what about 338.10(B)(4)? This says for interior runs of SE, you use the part I and II rules for NM cable. But the NM rules only seem to get you a physical protection run of conduit and not necessarily a complete conduit system.
Posted By: shortcircuit

Re: SER cable in conduit - 07/06/05 01:24 AM

312.5(C) requires cables to be secured to each cabinet,cutout box or meter socket enclosure...

314.17(B) requires the cable to be secured to boxes and conduit bodies...

These rules would seem to disallow the use of type SE cable in a raceway...

Posted By: master66

Re: SER cable in conduit - 07/06/05 02:01 AM

Went to inspect it today. two runs about 100' each. He said that he stripped the insulation off of the entire cable before installation.

He's driving me nuts. What would you do?
Posted By: gfretwell

Re: SER cable in conduit - 07/06/05 03:48 AM

He sure wouldn't like my answer.
When you strip the jacket off any cable assembly you end up with an unlisted/unlabelled conductor of unknown properties.
Posted By: caselec

Re: SER cable in conduit - 07/06/05 04:19 AM

If this was type NM cable I agree that the individual conductor type is unknown but all SER cable that I have seen uses type XHHW conductors and the conductor type is marked on the jacket. The individual conductors are also frequently marked with their type.

From the 2005 NECH:
According to the 2004 UL Electrical Construction Materials Directory, category TXKT (service cable) and category TYLZ (service-entrance cable rated 600 volts) are listed in sizes 14 AWG and larger for copper and 12 AWG and larger for aluminum or copper-clad aluminum. Type SE cable contains Types 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.

Posted By: caselec

Re: SER cable in conduit - 07/06/05 04:23 AM


Are these runs feeding the garage or just passing through an attached garage? Are the conduits installed above or below grade?

Posted By: renosteinke

Re: SER cable in conduit - 07/06/05 04:48 AM

Stripped the jacket off? That's an easy answer to find!

According to the UL White Book, "Type SE cable contains type RHW, RHW-2, XHHW, XHHW-2, THWN, or THWN-2 conductors." A further note, one that I missed yesterday, says the cable has a temp rating of 75, unless the type designation of the conductors is marked on the outer jacket, in which case the rating of the conductors is also the rating of the cable.
Posted By: gfretwell

Re: SER cable in conduit - 07/06/05 05:14 PM

If the internal conductors are properly marked I retract my statement.
Sorry for the confusion.
Posted By: boggerbutt2454

Re: SER cable in conduit - 07/07/05 02:03 AM

SER is a raceway. PVC is a raceway. You can not run a raceway in a raceway. You can use a short piece to protect the cable such as if the SER coming out or the ceiling in an unfinished basement into a panel.
Posted By: markp

Re: SER cable in conduit - 07/07/05 06:13 PM

Where does the code say you can't put a raceway in a raceway? I've seen big conduits with multiple smaller flex conduits pulled into them. Doesn't make it legal, but I don't recall on seeing a prohibition on installing a raceway inside another.

Also not sure if SE is a raceway. With today's definition, it may be. But I always thought a raceway allowed easy removal and reinsertion of the individual wires.

[This message has been edited by markp (edited 07-07-2005).]
Posted By: gfretwell

Re: SER cable in conduit - 07/07/05 08:11 PM

I suppose what you saw was technically a duct with "interduct" tubing in it. This will allow mixed voltages or methods in the same pipe. It is pretty common in telecom when you have a 6" underground and you want fiber or CAT5 in there. They protect the data with something similar to (same as?) smurf tube. Other wiring methods will be in there too.
Posted By: Roger

Re: SER cable in conduit - 07/07/05 10:29 PM

Bogger, SE, and USE are cable assemblies, not raceways see the definition of "Raceway" in article 100, and then see the definition of SE and USE in 338.2.

As pointed out by George, the 05 NEC has remedied the confusion of earlier cycles in the xxx.22 sections from 342 through 360 (with the exception of 354).

Note; the cables in 338 are not specifically prohibited from being installed in conduit in that article.

I also agree with Curt and Johns posts concerning the insulation type of the conductors.

Posted By: boggerbutt2454

Re: SER cable in conduit - 07/11/05 10:38 PM

Master 66 stated it was 4/0 SER in PVC. I agree USE would and should be acceptable as it has no jacket.
Roger I couldn't agree more about SER cable not being a raceway, unless of course an inspector tells you the definition states
"an enclosed channel of metal or nonmetallic materials designed expressly for holding wires, cables or etc." and he considers SE to meet that definition. The way it has been explained to me around here, if it is jacketed it is considered a raceway. NOT my definition but what I have to live with.
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