SER in conduit

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cindyfromnh said:
Is it ever permissible to run SER in conduit?
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Do you need to? If there are any LBs or bends involved you might want to use individual conductors and splice to the SER at a convenient point.
 
A question posed to a, code making panel 7 seven member (I'm not sure if the answer is reviewed by other members or not)


Question 1.
I am trying to find a Code article or reference to the use of SE cable in conduit underground. Chapter 9 states that for multiconductor cables, you have to use the actual dimension. This is not a problem, because you just measure the outside diameter. My question is, Is USE cable listed for use in conduit underground? ? R.P.

Answer 1.
The use of Type SE or USE in conduit either underground or aboveground is not prohibited by the NEC. However, neither of these cable types is listed for such use so the decision to accept or reject is up to the authority having jurisdiction (AHJ).
The following information may be helpful in considering such a decision. There are two serious concerns with this type of installation. The first is damage to the cable or individual conductors as they are pulled into the raceway. The other is the added resistance to heat dissipation. Both concerns can be addressed to some extent by using a conduit one size larger than required in Chapter 9. This reduces the friction of the pull, making it less likely that the conductors will be damaged during installation, and provides a larger air space to dissipate the heat buildup in the conductors under operating conditions. In general, such an installation is poor practice and should not be permitted where there are more than two ninety-degree bends in the run of raceway or where the circuit is expected to run at full load (80 percent of rated ampacity) for any length of time. The sole advantage to running SE cables in conduit underground is the ability to replace them, if necessary, without excavating. Of course, the use of THHW conductors in conduit provides this same advantage with none of the drawbacks identified above and is probably more economical as well. ? T.E. Trainor, CMP-7
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See 338.12 (2008) for uses not permitted. It would be acceptable aboveground for physical protection but not permitted underground.
 
M. D. said:
A question posed to a, code making panel 7 seven member (I'm not sure if the answer is reviewed by other members or not)
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The answer has been answered in the 2008 code

NEC 2008 said:
338.12 Uses Not Permitted.
(A) Service-Entrance Cable. Service-entrance cable (SE) shall not be used under the following conditions or in the following locations:
(1) Where subject to physical damage unless protected in accordance with 230.50(A)
(2) Underground with or without a raceway
(3) For exterior branch circuits and feeder wiring unless the installation complies with the provisions of Part I of Article 225 and is supported in accordance with 334.30 or is used as messenger-supported wiring as permitted in Part II of Article 396
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