existing 14/3 extended with 2x runs of 14/2

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shoon

Member
Location
Canada
I am working on a residential project where the panel was moved, and noticed that there is a run of 14/3 for 2 lighting circuits (one inside light, one outside) that was extended using 2 runs of 14/2. both neutrals are tied to the individual neutral on the 14/3, and both hot's are tied into a 2 pole 15amp breaker back at the panel (so that if someone turns the breaker off both legs are dead preventing shock from the neutral).

My question is, is this legal? (I suspect not) and if not what's the harm in leaving it?
thanks in advance!
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Not only legal but the dp breaker or 2 sp breakers with handle ties would be required on a multiwire branch circuit.
 

jeremysterling

Senior Member
Location
Austin, TX
Take a look at 310.4(A). Also, 300.3(B). Because of these codes, you will need to wreck out the 14/2 and replace it with 14/3.

I think Dennis thought the 14/3 is the homerun, which would be OK.
 

Smart $

Esteemed Member
Location
Ohio
I am working on a residential project where the panel was moved, and noticed that there is a run of 14/3 for 2 lighting circuits (one inside light, one outside) that was extended using 2 runs of 14/2. both neutrals are tied to the individual neutral on the 14/3, and both hot's are tied into a 2 pole 15amp breaker back at the panel (so that if someone turns the breaker off both legs are dead preventing shock from the neutral).

My question is, is this legal? (I suspect not) and if not what's the harm in leaving it?
thanks in advance!
Not legal on the supply side of the 14/3. You end up with parallel neutral conductors smaller than 1/0 [310.10(H) {2011 NEC}].

However, with NM you can disconnect one neutral (at both ends preferred but not required) and be in compliance. See 330.3(B) and (B)(3) therein, then 300.20(B) as referenced in 300.3(B)(3). I stress this is not something I agree with, but permitted regardless.
 
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Smart $

Esteemed Member
Location
Ohio
... Also, 300.3(B). Because of these codes, you will need to wreck out the 14/2 and replace it with 14/3.

...
Not exactly the only solution. See my other post.

PS: runiing the two 14/2 through the same connector will eliminate the need for cutting a slot.
 
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John120/240

Senior Member
Location
Olathe, Kansas
I am working on a residential project where the panel was moved, and noticed that there is a run of 14/3 for 2 lighting circuits (one inside light, one outside) that was extended using 2 runs of 14/2. both neutrals are tied to the individual neutral on the 14/3, and both hot's are tied into a 2 pole 15amp breaker back at the panel (so that if someone turns the breaker off both legs are dead preventing shock from the neutral).

My question is, is this legal? (I suspect not) and if not what's the harm in leaving it?
thanks in advance!

Take a look at 310.4(A). Also, 300.3(B). Because of these codes, you will need to wreck out the 14/2 and replace it with 14/3.

I think Dennis thought the 14/3 is the homerun, which would be OK.

Not legal on the supply side of the 14/3. You end up with parallel neutral conductors smaller than 1/0 [310.10(H) {2011 NEC}].

However, with NM you can disconnect one neutral (at both ends preferred but not required) and be in compliance. See 330.3(B) and (B)(3) therein, then 300.20(B) as referenced in 300.3(B)(3). I stress this is not something I agree with, but permitted regardless.

What am I not understanding ? Typical set up: 14-3 homerun to a two gang box for example. Red ties to Blk of 14-2, homerun

neutral to Wht of 14-2 then this circuit goes over there. Blk of 14-3 ties to Blk of 14-2, homerun neutral to Wht of this 14-2 then

this circuit wraps around this room. Is this not similar to the original question by shoon ?
 

Smart $

Esteemed Member
Location
Ohio
On second thought is the inverse what he has ? Two 14-2 homeruns tied to 14-3 at J box then split off to two 14-2's serving the inside

& outside lights ?
Correct, assuming the latter part. Two 14/2 at newest panel to 14/3 at previous panel location to two 14/2 at jbox somewhere.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
my bad - I see he ran two 14/2 home runs into a 14/3. Got that backwards - not compliant as Jeremy & Smart stated parallel neutrals.
 

kwired

Electron manager
Location
NE Nebraska
I will just say it is not preferred method but works in a pinch. Just don't parallel the neutrals and route cables together and through same KO's in metal enclosures.
 

kwired

Electron manager
Location
NE Nebraska
It didn't. I just elaborated in the second. :p

Compared to your post, I elaborated in the first, too... :D:D
crying1_zps8bd455e6.gif
 

shoon

Member
Location
Canada
Thanks for the responses guys!!

In all honesty, I'm probably just going to rip out the 14/2 and install some 14/3 since its such a short jaunt to the new panel. I'm merely asking for educational purposes at this point :)
Sorry for not being more descriptive, I'll describe the circuit starting from the panel.
2x 14/2's on a 2 pole go to a junction box where they connect to a 14/3 with neutrals doubled up. The 14/3 feeds 2 separate switches for lights. Originally, the 14/3 went straight into the panel

Although I do not have a NEC code book, the CEC has similar rules. 12-108 (1) states 1/0AWG or larger only for parallel runs, unless (3) its for control circuit / indicating instruments and devices, contactors, relays solenoids, etc.

With regards to leaving 1 of the neutrals disconnected, it will induce voltage into the "spare" wire will it not? (Hence why you mentioned not to route wires through the same knockout / or together.) Is it best to ground it at the panel and leave isolated at the junction box? I know that while terminating an analog cable dealing with 4-20mA signals you always ground the cable at the source and never the device.
 

Smart $

Esteemed Member
Location
Ohio
...

With regards to leaving 1 of the neutrals disconnected, it will induce voltage into the "spare" wire will it not? ... Is it best to ground it at the panel and leave isolated at the junction box?
It would if both ends are disconnected. But if capped off, where's it going to go??? However, best approach is to leave it connected to the neutral bus at the panel (if a service panel the ground bus could be one and the same... just making the distinction) and isolate at the jbox. No one will be the wiser for the most part. If you isolate at panel, someone seeing it at a later date will get that "deer in the headlight" look :blink: You may even want to put an informative tag on the other isolated end just so someone doesn't reconnect it.

But that's all moot if you are replacing with 14/3.


(Hence why you mentioned not to route wires through the same knockout / or together.)
No... you'd want to run the wires together as much as possible and through the same knockout. Where there is ferromagnetic metal (fmm) in close proximity to the conductors, circulating currents are induced in the fmm. Fmm between the conductors will have opposing currents and cause the metal to heat up [aka hysteresis]. That's why we have to cut slots in between knockouts in fmm when run through different KO's.
 
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