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Direct burial romex in conduit.

MASSDRIVER said:
What is the code for this?Yes or no?

Underslab plastic conduit.

Brent.
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Sounds to me like your looking at smurf conduit (Carbon Flex-Plus Blue). 2008 NEC, Electrical Nonmetalic Tubing. 362.10 Uses Permitted. (7) For wet locations indoors as permitted in this section or in a concrete slab on or belowgrade, with fittings listed for the purpose.

We could have some confusion by the terms used: "direct burial romex" and "in conduit". Not direct burial romex if in conduit, maybe?

Yep, you can use it.

Uncle Bob
 
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$ ~ $ ~ $



"I believe you can pull UF under a slab in smurf but why bother? (THHN)/THWN is cheaper."
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One reason could be that the installer may already have a boat-loadof the smurf & UF, and does not want to go purchase the

THHN/THWN [ i.e. - the cheapest route to compliance. ] ;)

$ ~ $ ~ $
 
~ ~ : ~ ~

gfretwell,

Do you have an NEC Article to refer to on the "smurf tubing" ?

Not everyone knows what "smurf tubing" is actually identified

as by its manufacturer [ and in the NEC ].

Thanks !

~ ~ : ~ ~
 
Smurf;

362.2 Definition.

Electrical Nonmetallic Tubing (ENT). A nonmetallic, pliable,

corrugated raceway of circular cross section with integral

or associated couplings, connectors, and fittings for

the installation of electrical conductors. ENT is composed

of a material that is resistant to moisture and chemical

atmospheres and is flame retardant.

A pliable raceway is a raceway that can be bent by hand

with a reasonable force but without other assistance.
 
I suppose you must be of or have kids/grand kids of the right age to know about Smurfs but the short answer is it was a cartoon about characters that were Carlon blue.

It was probably thought of as a dismissive term for this versatile raceway system.

I do remember the Carlon reps doing their road shows, many years ago, to any inspector or contractor venue that would have them, telling us of the virtues of this new wonder tube.

I have to admit I was skeptical but it does seem to work fairly well.

I have been torture testing some on my boat for over 20 years. Sun and salt water won't kill it.
 
Pardon me for being less than clear.

What we have is regular grey conduit than protrudes into a pony wall that backs an island cabinet. The plastic conduit has uf cable coming out to feed disposal, dw and island counter circuits. As I remember from my Lennar days we ran conduit from the island to the panel location up out of the stemwall. So constant under slab conduit. We have to run another circuit for the under counter micro in a new island.

I always thought (pardon my ignorance) that you never run "Romex", or a sheathed cable into conduit because of heat concerns. I was told that the city requires the uf cable even in conduit. So I'm trying to learn what's correct so I don't have to do it twice.

Also, I want to use the existing conduit of course without tearing out too much slab. I believe there is an inch pipe and a 1/2 inch pipe existing.

Thanks

Brent
 
MASSDRIVER said:
Pardon me for being less than clear. What we have is regular grey conduit than protrudes into a pony wall that backs an island cabinet. The plastic conduit has uf cable coming out to feed disposal, dw and island counter circuits. As I remember from my Lennar days we ran conduit from the island to the panel location up out of the stemwall. So constant under slab conduit. We have to run another circuit for the under counter micro in a new island.

I always thought (pardon my ignorance) that you never run "Romex", or a sheathed cable into conduit because of heat concerns. I was told that the city requires the uf cable even in conduit. So I'm trying to learn what's correct so I don't have to do it twice.

Also, I want to use the existing conduit of course without tearing out too much slab. I believe there is an inch pipe and a 1/2 inch pipe existing.

Thanks

Brent
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Both UF and NMC can be run in conduit but in underground installations the wire is required to be listed for wet locations along with above ground exsposed to weather when run in conduit in both scenarios inside the conduit is considered a wet location

(B) Wet Locations. The interior of enclosures or raceways installed underground shall be considered to be a wet location. Insulated conductors and cables installed in these enclosures or raceways in underground installations shall be listed for use in wet locations and shall comply with 310.10©. Any connections or splices in an underground installation shall be approved for wet locations.
 
There are really only 2 concerns with a cable in a raceway.

It is harder to pull without a lot of lube and you have a fill consideration since the cable has to be counted as a single conductor the size of the widest dimension of the cable for each one.

That really starts to bite you if you try 2 in the same raceway.

Heat is not an issue. You derate the same, based on the number of current carrying conductors.

(the same way, raceway size, does not affect derating).
 
For your info check out Chapter 9 Tables- Notes to the table

Note 2 states that Table 1 for fill is not applicable for sleeves only for complete runs of conduit. Derating would apply if there are more than 3 current carrying conductor's in the raceway even if it is a sleeve--

Note 4 allows a 60% fill if the complete conduit run is less than 24" and derating does not apply.

Note 9 states how to calculate multi-conductor cable fill where it applies.

For those without the book

Notes to Tables(1) See Informative Annex C for the maximum number of

conductors and fixture wires, all of the same size (total

cross-sectional area including insulation) permitted in

trade sizes of the applicable conduit or tubing.

(2) Table 1 applies only to complete conduit or tubing systems

and is not intended to apply to sections of conduit

or tubing used to protect exposed wiring from physical

damage.

(3) Equipment grounding or bonding conductors, where installed,

shall be included when calculating conduit or tubing

fill. The actual dimensions of the equipment grounding

or bonding conductor (insulated or bare) shall be used

in the calculation.

(4) Where conduit or tubing nipples having a maximum

length not to exceed 600 mm (24 in.) are installed between

boxes, cabinets, and similar enclosures, the

nipples shall be permitted to be filled to 60 percent of

their total cross-sectional area, and 310.15(B)(3)(a) adjustment

factors need not apply to this condition.

(5) For conductors not included in Chapter 9, such as multiconductor

cables and optical fiber cables, the actual

dimensions shall be used.

(6) For combinations of conductors of different sizes, use

Table 5 and Table 5A for dimensions of conductors and

Table 4 for the applicable conduit or tubing dimensions.

(7) When calculating the maximum number of conductors

permitted in a conduit or tubing, all of the same size

(total cross-sectional area including insulation), the

next higher whole number shall be used to determine

the maximum number of conductors permitted when

the calculation results in a decimal of 0.8 or larger.

(8) Where bare conductors are permitted by other sections

of this Code, the dimensions for bare conductors in

Table 8 shall be permitted.

(9) A multiconductor cable or flexible cord of two or more

conductors shall be treated as a single conductor for

calculating percentage conduit fill area. For cables that

have elliptical cross sections, the cross-sectional area

calculation shall be based on using the major diameter

of the ellipse as a circle diameter.
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Seldom do I find cable in conduit. When I do, it is outdoors for an A/C or spa. I surmise that NMC is hardly ever in conduit because it doesn't need to be in conduit and Romex doesn't pull easy, requires larger conduit and must be more expensive than individual wires.
 
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Ref note 2

These tables are not just overreach by an out of control government. There are good, purely physical, reasons why these are good guidelines. Certainly you can stuff a lot of wire in a short straight piece of pipe but even one bend in it will quickly demonstrate why they have fill calcs.
 
gfretwell said:
I have been torture testing some on my boat for over 20 years. Sun and salt water won't kill it.
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That is the most practical info I've seen in a long time. I'm with ya!

BS
 
BSSTG said:
That is the most practical info I've seen in a long time. I'm with ya! BS
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As a totally non-electrical use, I sleeved my steering cable with 3/4" smurf, running under a pontoon boat in salt water and it is as good as new for all that time.
 
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