14s and 12s connected together in a box

[Marc M]

Question... looking for a NEC code that basically says two different size conducts cannot be spliced in a J box. The contractor ran 12s from the panel and in the box connected the lights and other receptacles (in the same room) to 14's. I guess he was either trying to save money or pre ran the interior wiring?


http://www.inspectionnews.net/home_inspection/attachment.php?attachmentid=35345&stc=1

[david shapiro]

Question... looking for a NEC code that basically says two different size conducts cannot be spliced in a J box. The contractor ran 12s from the panel and in the box connected the lights and other receptacles (in the same room) to 14's. I guess he was either trying to save money or pre ran the interior wiring?

Sorry, Marc, but the only applicable rule for a general-purpose branch circuit concerns the OC device rating. Practically, it is easy to envision someone down the road saying, "My my, your 15 amp breaker's been tripping, yet it feeds a 12AWG cable; I'll just swap it out for a 20." But that's just a reason for a cautionary note. As a contractor, i remember running 10AWG ACHH home runs to reduce voltage drop in a residence, and splicing to 12AWG ACHH in each room.

[Marc M]

Sorry, Marc, but the only applicable rule for a general-purpose branch circuit concerns the OC device rating. Practically, it is easy to envision someone down the road saying, "My my, your 15 amp breaker's been tripping, yet it feeds a 12AWG cable; I'll just swap it out for a 20." But that's just a reason for a cautionary note. As a contractor, i remember running 10AWG ACHH home runs to reduce voltage drop in a residence, and splicing to 12AWG ACHH in each room.

Wow, great answer. I had no idea.

But aren't the 14s overfused with a 20a disconnect?
Thank you very much sir.

[Jerry Peck]

Question... looking for a NEC code that basically says two different size conducts cannot be spliced in a J box.

Marc, my answer is similar, but different, than David's answer.

The part that is similar is that the maximum OCPD is required as specified by the code for each size conductor.

The part that is different is:



The contractor ran 12s from the panel and in the box connected the lights and other receptacles (in the same room) to 14's. I guess he was either trying to save money or pre ran the interior wiring?

- Splicing #14s to a #12 is not allowed if the OCPD is rated for the #12 conductors.

Here is something to consider: how long is the circuit run (out and back)? The electrical contractor may have upsized the home runs for voltage drop considerations, in which case the OCPD 'might' be 15 amps for #12, but that creates the issue David raised about putting in a 20 amp breaker later.

As David pointed out to an answer to a previous question of yours, the code is applicable to the installation at the time of installation, not at some future time.

I had a few contractors (while I was working for them to inspect their homes to make sure their homes were done properly, i.e., the homes were not starter homes, the homes were $5mil to $30mil, thus trying to meet "minimum code" was not their objective), and as such, the contractor had his electrical contractor run #12 for most 15 amp circuits (except for short runs). The electrician never tried to go from the #12 home run to switches and receptacles using #14. The main thing the electrical contractor did not like was that #12 could not be backstabbed into the devices, all device connections were under the screw terminals.

I explained the advantages of remote panels located in a central location to shorten the lengths of the circuit runs, thereby avoiding voltage drop issues when using #14 for 15 amp circuits, which they started doing. The contractors then installed the main panels in the garage (the service equipment panels were located outside) near where the heavy loads typically would be, i.e., laundry and kitchen; the remote panels would be upstairs and over by the master suites (one master suite was 3,500 sf in itself and had three bathrooms in it ... when you gotta go, you gotta go - per the owner).

[Jerry Peck]

As a contractor, i remember running 10AWG ACHH home runs to reduce voltage drop in a residence, and splicing to 12AWG ACHH in each room.

This is my third time typing this as the board returned errors, losing everything, so I will make it shorter this attempt.

I had similar done, and suggest the contractor install a gutter/junction box next to the panel. The #10s were run into the gutter, spliced to short lengths #12s, with the #12s then run into the panel and to the OCPDs. Open the panel and 'every thing looks like it should'.

Open the gutter and there was a note explaining what was done and why so no one messed with the #10s.

[ROBERT YOUNG]

Question... looking for a NEC code that basically says two different size conducts cannot be spliced in a J box. The contractor ran 12s from the panel and in the box connected the lights and other receptacles (in the same room) to 14's. I guess he was either trying to save money or pre ran the interior wiring?


Morning, Marc. Hope to find you well and in good spirits today.

As to your question, "splicing different wire/conductor AWG sizes," or as to your reference, "two different size conducts cannot be spliced in a J box." The NEC allows for splicing conductors of different awg sizes, TO A POINT, however, specific requirements must be met.

NEC section 305.2. C.1 states that conductors of different sizes, intended for termination at the same terminal location, ie: the outlet enclosure in your image, shall be spliced together. NEC Table 305.2. C.1 specifies the following requirements for splicing different wire sizes.
1: Splices must/shall be made with an approved splicing device. 2: The larger conductor shall be at least one size smaller than the highest ampacity used on that circuit. 3: The smaller conductor shall have an ampacity of at least 75% percent of the largest conductor. 4: The splice shall be accessible for future maintenance.
Then the circuit cable run lengths rules apply.

Hope that helps.

Good thread by the way.
Happy to see the regulars are mostly here:-)