I'm talking about something like this Type LB Conduit Body
asked Dec 13, 2013 at 16:07
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1Most code states that the splice has to be accessible. It appears that device is designed specifically for that purpose.– DA01Commented Dec 13, 2013 at 16:22
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It is not clear to me whether it is designed to permit splicing or to facilitate pulling wires around the corner.– ThePopMachineCommented Dec 13, 2013 at 16:26
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I agree with DA01. Looks accessible to me, and unless this is the main coming into the breaker, it should meet the requirements Tester101 mentions in his answer.– user4302Commented Dec 14, 2013 at 5:12
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2 Answers
Depends.
- If the conductors are 6 AWG or smaller.
- There is enough free space.
- It's not a short radius conduit body.
- The volume is durably and legibly marked by the manufacturer.
Only then can the conduit body contain splices.
In your specific case, I don't see the volume listed in the specifications section on the Home Depot page. So you'd have to check the fitting itself, to determine if the manufacturer has marked the volume. You didn't say what size wires you're pulling, so I can't answer that definitively. You also didn't mention the number of conductors, so it's impossible for me to do the fill calculations.
The Codez
National Electrical Code 2014
ARTICLE 314 Outlet, Device, Pull, and Junction Boxes; Conduit Bodies; Fittings; and Handhole Enclosures
II. Installation
314.16 Number of Conductors in Outlet, Device, and Junction Boxes, and Conduit Bodies. Boxes and conduit bodies shall be of an approved size to provide free space for all enclosed conductors. In no case shall the volume of the box, as calculated in 314.16(A), be less than the fill calculation as calculated in 314.16(B). The minimum volume for conduit bodies shall be as calculated in 314.16(C).
(C) Conduit Bodies.
(1) General. Conduit bodies enclosing 6 AWG conductors or smaller, other than short-radius conduit bodies as described in 314.16(C)(2), shall have a cross-sectional area not less than twice the cross-sectional area of the largest conduit or tubing to which they can be attached. The maximum number of conductors permitted shall be the maximum number permitted by Table 1 of Chapter 9 for the conduit or tubing to which it is attached.
(2) With Splices, Taps, or Devices. Only those conduit bodies that are durably and legibly marked by the manufacturer with their volume shall be permitted to contain splices, taps, or devices. The maximum number of conductors shall be calculated in accordance with 314.16(B). Conduit bodies shall be supported in a rigid and secure manner.
(3) Short radius conduit bodies. Conduit bodies such as capped elbows and service-entrance elbows that enclose conductors 6 AWG or smaller, and are only intended to enable the installation of the raceway and the contained conductors, shall not contain splices, taps, or devices and shall be of sufficient size to provide free space for all conductors enclosed in the conduit body.
Examples of short radius conduit bodies
Capped Elbow
Box Fill Calculation
For each current carrying conductor that terminates within the box, you'll add 1. So if you're pulling one ungrounded (hot) conductor, one grounded (neutral), and one grounding conductor. If you want to splice within the box, the calculation would look like this.
Ungrounded (hot) 1
Ungrounded (hot) 1
Grounded (neutral) 1
Grounded (neutral) 1
--------------------------
4
If grounding conductors are used, you'll add 1.
Current Carying 4
Grounding 1
--------------------------
5
Once you have the conductor count, you'll use Table 314.16(B) to determine the required volume.
NOTE: You'll always base the calculation off the largest conductor used. so if you have a #14 grounded (neutral) and a #12 ungrounded (hot), you'll use 2.25 because of the #12. If you're using grounding conductors that are a different size than the current carrying conductors, you'll multiply them separately (#12 hot, #12 neutral, #14 ground = 2 x 2.25 + 1 x 2.00).
14 AWG
If the largest conductor used is 14 AWG, you'll multiply the conductor count by 2.00 according to Table 314.16(B).
`5 * 2.00 = 10.00'
Which means the box must have a volume of at least 10 cubic inches, if you want to splice within it.
12 AWG
If the largest conductor used is 12 AWG, you'll multiply the conductor count by 2.25.
5 * 2.25 = 11.25
So in this case, the box must have a volume of at least 11.25 cubic inches.
3 Ungrounded (hot) Conductors
If you were pulling 3 ungrounded (hot) conductors, the calculations would look like this.
Ungrounded (hot) 1
Ungrounded (hot) 1
Ungrounded (hot) 1
Ungrounded (hot) 1
Grounded (neutral) 1
Grounded (neutral) 1
Grounding 1
--------------------------
7
14 AWG
7 * 2.00 = 14 cubic inches
12 AWG
7 * 2.25 = 15.75 cubic inches
answered Dec 13, 2013 at 16:49
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Thanks. For purpose of this question, assume it is just a cable-to-cable splice of 12-2 or 12-3 Type NM. Commented Dec 13, 2013 at 17:09
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@ThePopMachine Does the fitting have a volume marked on it, and if so, what is it? Commented Dec 13, 2013 at 17:10
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From what I recall, there is a volume marked (molded) on the inside of these.– EcnerwalCommented Dec 13, 2013 at 17:18
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For Carlon: 1/2" 4.0 c.i., 3/4 12.0 c.i., 1" 12.0 c.i. - HD's specs page is useless, but Carlon publishes the data.– EcnerwalCommented Dec 13, 2013 at 17:25
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I realize this answer is a decade old, but the fill calculation method described by tester101 is wrong. I'm surprised no one noticed. He says volume of the largest cc conductor in the box is to be multiplied by the conductor count to get the required volume. Not true, the volumes of conductors are calculated based on their sizes then totaled. Then he goes on to say the grounding conductors should all be done separately if grounds are a different size than cc conductors. This is also wrong. Grounds get one allowance based on largest (updated to 1 for 1st 4 egc 1/4 each addtl egc). Commented Sep 1, 2023 at 20:55
12-2 will work, 12-3 is too much.
If you are using a 3/4" Carlon, it's 12 cubic inches and should be marked. 12-2 with ground, spliced, needs 5X 2.25", 11.25 cubic inches, passes. 5 is two neutrals and two hots that terminate in the box, plus one for the ground. 12-3 with ground needs 7X 2.25, 15.75 cubic inches, fails (unless you increase to a 1-1/4" LB with 32 cubic inch volume).
answered Dec 14, 2013 at 14:52
