How to determine what size romex wire you need: for your electrical project

[strumpeteer]

First of all, thank you taking the time to share your knowledge to help others. IMO, if you are certainly sure that the wire you found was a 14AWG on a 20 amp breaker, I really hope you changed it to a 15 amp breaker for the safety of you and your family. :)

[VideoJoeKnows]

@strumpeteer I probably should've changed it but I felt there was no harm to do it this time, as you would not be able to add to this circuit, given the location used was under the AC unit & would be very difficult, if not impossible, to add anything else on this particular circuit, given the location. Thanks for your comments. Joe :0

[cardoworld22]

Great post!!!!!!

[VideoJoeKnows]

@cardoworld22 Thanks for taking time out to send me your comment. Keep watching....as the more you watch, the more you'll learn!!....lol. Joe :0

[DAZUPYOU]

Now that is a very nice tip thank you:):)

[Chewylu103]

Joe, If the wire you are going to get your power from is fed from a 20amp breaker and you suspect it might be a 14 awg wire, then you should change out the circuit breaker to a 15a circuit breaker. The reason being is that you are now modifying this circuit and therefore have to correct it. Also you need to use the same wire size that the circuit started with, unless it is a correction factor for voltage drop which in this residential application is not the case.

[VideoJoeKnows]

@Chewylu103 All the breakers in the subpanel are 20 amp & I do not want to change this. If the existing wiring is fine to run the existing AC unit, then I can install a larger wire but not a smaller one than the existing. I think code might be to have no breaker smaller than a 20 amp breaker (for these condos?) but all 20 amp breakers should have a wire size of 12 gauge & no smaller. The inspector may have missed it. Thanks for your comments. Joe :0

[Chewylu103]

@VideoJoeKnows If the wire is 14-2 on a 20 amp breaker, that would be wrong and would warrant changing it if you must use that circuit or running a new circuit, you cant just go up to a 12-2 on a 20 amp circuit that is run in 14-2 its wrong to start with and its just adding to the mess. now if you are wrong in the video and that is actually a 12-2 you are getting your power from then what you are doing is fine. I am reading the code book now about the only 20a circuits in a condo.

[VideoJoeKnows]

@Chewylu103 It appears that the actual wire coming into the initial box is a 14-2 w/ground. If so, they should've installed on a 15 amp breaker. I added 12-2 w/ground to run the added timer. That would be OK to do in this instance as I am increasing the size wire & not decreasing what was existing. I believe the existing AC unit can be run on a 15 amp circuit so I would think the actual 14-2 w/ground will hold & will never be in need of a 20 amp breaker so it should work. Thanks. Joe :0

[VideoJoeKnows]

@Chewylu103 The timer is also rated for a 15 amp circuit so I should be fine. I could've run a 14-2 w/ground it looks like. I had the 12-2 w/ground handy so I thought I would be safe either way. Thanks again for all your input as it will be beneficial to any viewer who reads these comments. Joe :0

[Chewylu103]

@VideoJoeKnows Code requires you to stick with the wire you started with its not "ok" to code. I cannot condone your decision to use the 12-2 strictly because you say it is safer because its not. The safer way would be to use the correct size wire which is 14-2, reason being that later down the line someone could open that up that box and be like great! i have a 20 circuit here with 12-2 and put something rated for 20 amps on it, who knows what will become of that circuit later down the line.

[Chewylu103]

@VideoJoeKnows There are codes and standards in place for a reason so that at any point later down the line another electrician can pick up where the last guy left off and know that it is all up to par. People need to know just because the wire is bigger does not mean its right, it throws off the next guys perception of the circuit thus creating a fire hazard. hypothetically if you had a load rated for 12-2 on your 14-2, your 14-2 could possibly burn up and create a fire.

[VideoJoeKnows]

@Chewylu103 You are correct. Hypothetically if anyone added to this circuit & saw that the previous installer used 12-2 wire, they might make the assumption they could add additional 20 amp rated items to this circuit & thus create a potential fire hazard since the initial wire/cable installed was only 14-2 which should've been installed with a 15 amp breaker. Thanks for your additional comments. Joe :0

[Chewylu103]

@VideoJoeKnows National Electrical Code also states that if you change it you fix it, so you are obligated to change out that breaker to the correct sized breaker.

[VideoJoeKnows]

@Chewylu103 Thanks for your attention to details. Joe :0

[strumpeteer]

@Chewylu103 IMO, using a 12G wire on a 15amp breaker is fine.

In the future, even if the idiot electrician, who assumes that a circuit is

automatically on a 20A breaker just because he sees a 12G wire,

will eventually learn that it's actually on a 15A breaker when he goes

to the panel to turn off the power to that circuit (assuming that he

doesn't work on live circuits. )

[Chewylu103]

@strumpeteer yes i agree using a number 12 on a 15amp breaker is fine, because the wire is oversized for that breaker and the breaker will trip before current reaches the wires ampacity. My concern was that he was giving out false information, he said that the 14 was on a 20 amp breaker if i remember correctly, its wrong to just add a 12awg potentially masking a problem. because you see the breaker at 20 amps, the wire at 12 and run 20amp equipment. boom, 14awg melts, possible fire.

[VideoJoeKnows]

@Chewylu103 The electrician probably checked the load on the AC unit, when intstalled, & determined that a 14 gauge wire was ok?... as the AC unit has been here for around 6 years & nothing has happened to it.....yet! The AC was not upgraded but if it ever was, should not be any larger than what's there now. The breakers were in a condo & maybe the requirement was that this condo was not to have any 15 amp breakers in the sub-panel?....not sure. Thanks for your comments. Joe :0

[strumpeteer]

@Chewylu103 ....and even if the careless electrician

doesn't check which breaker goes to what circuit, a 15A breaker will

obviously trip before overloading the 14AWG with 20amp rated

stuff.:)

[Agapecate]

thank you Joe for your great advices

great work

kasia

[VideoJoeKnows]

@Agapecate Thank you for continuing to check out "joe". The more you watch, the more you'll know!!....lol :0

[Kittielips]

Gosh...How have you managed to guage this? Get your top off and grease yourself down!

5*****.

Jennie. x.

[VideoJoeKnows]

@Kittielips There you are. Where have you been keeping yourself lately?  Joe :0

[Kittielips]

@VideoJoeKnows

I locked myself in the bedroom because I put the hinges on back to front.....Back to D.I. Y. school for me!

Jennie. x.

[VideoJoeKnows]

@Kittielips Glad to hear you were able to get out of the bedroom......pesky hinges. I guess that means you haven't been watching enough of "joe"!!.....lol :0

[VideoJoeKnows]

@thedelih Thanks for your comments. Hope this helps you determine what size wire you need for your project. Joe :0

[67tr876]

15 amps you need 14 Gage , 20 Amps 12 Gage ,30 amps 10 Gage

[VideoJoeKnows]

@67tr876 Thanks for your input. Joe  :0

[WannaBeDj100]

@67tr876 Whata bout voltage drop? after so far of a run you get more voltage drop on a smaller wire? So there for, I think you have to up your wire gage to account for this? (Am I right or wrong?) I think this is true

[67tr876]

@WannaBeDj100 No voltage drop is something that is going to be there if you have more then one thing on a line. Voltage will not go down do to smaller wire. Voltage drop is when you have a load on a line. AC power can go a long way with out voltage drop is its not loaded. DC power drops volts after long runs but both have nothing to do with smaller wire and that making the volts drop.