Some electrical circuits in my older home (built in 1974) have me concerned due to my limited knowledge in the electrical area. I have a double 20 amp breaker in my panel that uses a 10-3 cable to a junction box where it breaks into two 12-2 circuits. One of the 12-2 circuits then breaks into one 12-2 line and a second 14-2 line. Can I safely have a circuit that goes from double amp 20 with 10-3 cable to 12-2 cables to a 14-2 cable?
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
Ford Motor Company slashes prices for some F-150 Lightning models to stimulate demand for electric vehicles (EVs).
Featured Video
SawStop's Portable Tablesaw is Bigger and Better Than BeforeHighlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
Everything you described is normal for a shared-neutral circuit, up to the 14-2 part. In my jurisdiction you cannot protect a #14 wire with a 20A breaker. It sounds like it may have been added after-the-fact by a previous owner.
The first wire does not need to be 10-3 -- 12-3 would have been adequate. However, the 10-3 is not a problem or a code violation.
You can split as many 12-2 lines off the original circuit as you want -- nothing in code to prevent it (with a few obscure exceptions) and nothing hazardous in doing so (within reason).
The 14-2 line should not (by code) be connected to a 20A circuit. #14 romex is limited to 15A in current code.
This is not even a "current
This is not even a "current code" situation. 14ga wire has been required to be protected with 15a breakers since the Hoover administration. You might be able to find a 2 pole 15/20a breaker but it would be easier to just put in a single 15 and a 20 with a listed handle tie.
Another legal solution
Gfretwell said >>... it would be easier to just put in a single 15 and a 20 with a listed handle tie.<< This is a practical, safe, legal solution.
Another solution would be to change the run of 14/2 to 12/2, if the existing 14/2 is accesible this may be a simpler / cheaper way to go.
Which way you go depends upon accessibility of the 14/2 cable run(s?), and whether you can tolerate the reduction in amp rating for the rest of the circuit leg which has the 14/2 cable present in it.
The 10/3 section of cable is not a problem either way - being "down-rated" merely serves to reduce voltage drop in your 20A circuits at the point of use.
By chance is the 10/3 cable to your first junction box a relatively long cable run? If so, it was probably installed "on purpose" to reduce voltage drop.
Jim
Another thing bothers me here. You said 10-3? Is that aluminum? They were still using it in 1974. That will rip open a whole new can of worms.
Al worms?
>>....Is that aluminum?......... That will rip open a whole new can of worms.<<
Hadn't considered the Al possibility for that 10/3......
If Al wire then the 20A breaker is sized correctly for the 10/3 and 12/2 copper; the 14/2 run of cable is still a problem.
Not that large a worm can even if the 10/3 is Al. 1st j-box gets 4 listed Al-to-Cu wire nuts, panel wire ends get some Al anti-oxidizer and you are done with the Al wire issue. 14/2 still is problematic with 20A breaker - never seen any 14/2 Al cable.
The purple, Ideal, Al-to-Cu wire nuts are pricey at ~ $2.40 each at a big box. but they solve the problem quickly. They have about the same wire capacity as a red wire nut. $10. worth and you are done. Sometime available as a 2 pack for ~$ 5.
These:
Twister Al/Cu (Card of 10)
Catalog # 30-765
Features
Aluminum-to-Copper connector provides a secure connection while preventing aluminum corrosion
Specially formulated corrosion-resistant compound provides cooler connections and increased conductivity
Accepts 1 #12 Al sol. w/ 1 #18 Cu AWG min. and 1 #10
Don't know why my cut and paste came out this way - last line should read ".......#18 Cu AWG min. and 1 #10 Al solid w/1 or 2 #10 Cu solid max." Therefore, 1 #10 Al solid w/ 2 #12 Cu solid is within their approved range.
Jim
There are also some good CU-AL insulation-piercing connectors. I forget the name, but I keep a few in my kit of random stuff.