Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 11-08-2009, 04:46 PM   #1
Wire Chewer
 
Red Squirrel's Avatar
 
Join Date: Jun 2009
Location: Ontario, Canada
Posts: 3,200
Share |
Red face

20A circuit on 14/2


I have a couple 20A circuits in my house and noticed they're all on 14/2 wire. I know this is against code and should be 12, but it is existing wiring.

My question is, is it safe? Can 12awg handle 20A safely without posing a hazard? I know the code slightly over sizes to be on the safe side. I have two spare 15A breakers so I could switch out the circuits that I think are more likely to hit over 15A, but I wont be able to cover them all. It's not like they're using 20A constantly, but if it really is a big hazard then I will want to fix that, probably by buying some 15A breakers to replace them.

Red Squirrel is offline   Reply With Quote
Old 11-08-2009, 06:13 PM   #2
Remodeling Contractor
 
Join Date: Dec 2008
Location: Sandy Hook, CT
Posts: 3,590
Default

20A circuit on 14/2


it is a big hazard. This means that an overload will burn the wire before the breaker trips. When the wire burns (it is inside the wall) the house burns. The code is a minimum standard not overkill. 14 wire on 15 amp breakers. 12 wire on 20 amp breakers. Size the breakers to whatever wire size is there.

Bob Mariani is offline   Reply With Quote
Old 11-08-2009, 06:16 PM   #3
Electrical Contractor
 
kbsparky's Avatar
 
Join Date: Sep 2008
Location: Delmarva
Posts: 3,361
Default

20A circuit on 14/2


Are either of those circuits connected to an outside A/C unit? There are exceptions where a 20 Amp breaker can be legally connected to a piece of #14 gauge wire.
__________________
-KB

Life is uncertain -- eat dessert first!!
kbsparky is offline   Reply With Quote
Old 11-08-2009, 06:40 PM   #4
" Euro " electrician
 
frenchelectrican's Avatar
 
Join Date: Apr 2006
Location: WI & France { in France for now }
Posts: 5,369
Default

20A circuit on 14/2


Quote:
Originally Posted by Bob Mariani View Post
it is a big hazard. This means that an overload will burn the wire before the breaker trips. When the wire burns (it is inside the wall) the house burns. The code is a minimum standard not overkill. 14 wire on 15 amp breakers. 12 wire on 20 amp breakers. Size the breakers to whatever wire size is there.
Bob.,

If I were you I will becarefull when you stated that word.

Let you know I am not being harsh but give you a head up we sized the breaker with smallest conductor in the circuit so if that person have mixed bag of #14 , #12 , #8 AWG sizes what I do ? size the breaker to the smallest conductor which it is #14.

The other thing KBsparky mention A/C unit there is extempt from the regulations this is used for hardwire A/C plus hardwired motors and it is stated clear in Art 430 for motors Art 440 for HVAC motors so that is one of few spots but again that is limited useage. { typically we will sized by mimuim running amp and max OCPD size per nameplate info on it }

Merci.
Marc
frenchelectrican is offline   Reply With Quote
Old 11-08-2009, 06:49 PM   #5
Member
 
Join Date: Jan 2009
Location: South of Boston, MA
Posts: 17,248
Default

20A circuit on 14/2


Yes, #14 has some spare "room" in the rating
Table 310.16 (cable) lists it as 20a @ 60 & 75 degree, 25a @ 90 degree
That's with an ambient Temp of 86

310.17 (free air) lists it as 25a @ 60, 30 @ 75 degree, 35a @ 90 degree

Each column is different types of wire too

Would I be worried about it? Only if you think you will be pulling 15a+ for a while - continous load
I've pulled ~2600w on a 20a circuit for about 3-5 minutes before it tripped

I would upgrade it when you can...better sooner then later
Years ago there were not as much electronic devices as these days

12awg can handle 20a...I think you are asking about 14g tho
Are you sure its 14g wire....marked ?

Problem with running 15a at higher then its rating is you will heat up the wire
That can possibly cause a fire before the breaker will trip
Scuba_Dave is offline   Reply With Quote
Old 11-08-2009, 10:02 PM   #6
Wire Chewer
 
Red Squirrel's Avatar
 
Join Date: Jun 2009
Location: Ontario, Canada
Posts: 3,200
Default

20A circuit on 14/2


Yeah pretty sure it's all 14 but I'd have to check every single cable to be sure, could be there actually is some 12. This house was built in the 60's so maybe it was not code then and they just used all the same wire. It is labeled "industrial wire" if that matters.
Red Squirrel is offline   Reply With Quote
Old 11-09-2009, 08:09 AM   #7
Member
 
Join Date: Nov 2007
Location: Nashua, NH, USA
Posts: 6,856
Default

20A circuit on 14/2


Quote:
Originally Posted by Red Squirrel View Post
could be there actually is some 12.
The entire circuit has to be 12 or heavier wire before you may use a 20 amp. breaker.
__________________
Stop wasting time re-adjusting the pattern. Have several lawn sprinklers, one for each pattern.
AllanJ is offline   Reply With Quote
Old 11-09-2009, 08:27 AM   #8
Member
 
Join Date: Jan 2009
Location: South of Boston, MA
Posts: 17,248
Default

20A circuit on 14/2


One note, older 12g can be white or black or other sheathing
So don't go by the color of the sheathing
As far as I know it should have some marking unless it is a cloth covering
Scuba_Dave is offline   Reply With Quote
Old 11-09-2009, 11:28 AM   #9
Member
 
Join Date: Sep 2008
Location: SoCal
Posts: 1,794
Default

20A circuit on 14/2


Myself, I would put on a 15a breaker - easy enough to do - peace of mind - and one less thing for a home inspector to tag next you sell the house.
vsheetz is offline   Reply With Quote
Old 11-09-2009, 11:51 AM   #10
Member
 
Join Date: Jul 2008
Location: NW of D.C.
Posts: 5,990
Default

20A circuit on 14/2


Roughly, 20A through a #14 will give you (20/15)^2 = 1.8x the rated temp. rise above ambient, so 60C wire insulation in a 30C environment will be seeing ~84C.

Wood slowly chars @ 120C.

http://www.electrician2.com/articles/ampacity.htm

Last edited by Yoyizit; 11-09-2009 at 11:54 AM.
Yoyizit is offline   Reply With Quote
Old 11-09-2009, 01:02 PM   #11
Member
 
Join Date: May 2009
Location: Brooklyn, New York (NYC)
Posts: 1,124
Thumbs up

20A circuit on 14/2


Quote:
Originally Posted by kbsparky View Post
Are either of those circuits connected to an outside A/C unit? There are exceptions where a 20 Amp breaker can be legally connected to a piece of #14 gauge wire.
WADR (With all due respect) Where the "Code" allows oversizing (of 25% (125% of proper wire size) is with the overload protection for motors in an industrial setting. For several reasons. (BTW I'm just stating the obvious) a) A motor draws more at starting time than its running rating; b) The motor has internal Thermal protection; Whereas in a residential setting, the motors are small enough to be covered for the starting load, too.
spark plug is offline   Reply With Quote
Old 11-09-2009, 02:19 PM   #12
Wire Chewer
 
Red Squirrel's Avatar
 
Join Date: Jun 2009
Location: Ontario, Canada
Posts: 3,200
Default

20A circuit on 14/2


Quote:
Originally Posted by Scuba_Dave View Post
One note, older 12g can be white or black or other sheathing
So don't go by the color of the sheathing
As far as I know it should have some marking unless it is a cloth covering
Yeah all wires are green, I was reading off of them. I actually saw one that is 12 coming out of the panel. I'd have to trace it. There's lot of places I can't trace like what is inside the walls so could be it's 14. Think I'll just go ahead and swap the breakers to be on the safe side. The only 20 amp I know is ok is my dishwasher because I ran that cable.
Red Squirrel is offline   Reply With Quote
Old 11-09-2009, 03:31 PM   #13
Licensed Pro
 
Join Date: Mar 2007
Location: SC
Posts: 1,528
Default

20A circuit on 14/2


Quote:
Originally Posted by spark plug View Post
WADR (With all due respect) Where the "Code" allows oversizing (of 25% (125% of proper wire size) is with the overload protection for motors in an industrial setting. For several reasons. (BTW I'm just stating the obvious) a) A motor draws more at starting time than its running rating; b) The motor has internal Thermal protection; Whereas in a residential setting, the motors are small enough to be covered for the starting load, too.
There is no restriction to just industrial settings for HVAC compressors. You treat them the same in residential and commercial.
__________________
"Life is hard. Life is harder when you're stupid." John Wayne
HouseHelper is online now   Reply With Quote
Old 11-09-2009, 04:33 PM   #14
Member
 
Join Date: Mar 2009
Location: Pennsylvania
Posts: 719
Default

20A circuit on 14/2


Quote:
Originally Posted by Red Squirrel View Post
Yeah all wires are green, I was reading off of them. I actually saw one that is 12 coming out of the panel. I'd have to trace it. There's lot of places I can't trace like what is inside the walls so could be it's 14. Think I'll just go ahead and swap the breakers to be on the safe side. The only 20 amp I know is OK is my dishwasher because I ran that cable.
Now your talking, way to go better to be safe than sorry.

If you have any problems with the Fifteens at least you'll still be around to find out what the problem was.
SULTINI is offline   Reply With Quote
Old 11-09-2009, 08:13 PM   #15
Former Contractor
 
PTP WX's Avatar
 
Join Date: Oct 2009
Location: Wisconsin
Posts: 43
Default

20A circuit on 14/2


Our neighbors about 1/2 mile down built a new house a year ago, they left the garage outdoor flood lights on overnight and burned the whole house down, not sure on specifics but the electrical contractor put in 14 gauge on a 20 amp for the floods and it overheated in the garage attic. They just finished rebuilding for the 2nd time.

I have a question on topic about loads and construction. My dad was an electritian for 37 years, and I swear he finds more "issues" with electric than any builder or home inspector. When he built his house about 10 years ago, he ran everything on 12 gauge and in conduit. I thought at the time that it was a little overkill.

Anyhow, with 150 or 200 A service on nearly every home built, why do the builders mix & match 15 amp / 14 gauge & 20 amp / 12 gauge. My service panel is about 1/2 15's and 1/2 20's. Kitchen & Baths on 20's .... Bedrooms on 15's. Now my house is roughly 20 years old, if I want to add a computer and desk light to my sons bedroom I will likely need to fish 12 gauge and rewire 2 bedrooms.

Why can't the builders just run 12 gauge everywhere so there is a little extra when / if needed? Is this some penny pinching electrical engineer deciding that 14 gauge will save $0.11 per foot in construction, or is there a safety concern with having 12 gauge only carrying minor loads?

PTP WX is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Tripping breakers,neutrals,120 volts and 240 volts OH My!!! Stubbie Electrical 17 06-11-2011 06:09 AM
Need a wiring diagram Mooreski Electrical 46 03-12-2011 03:25 PM
Wiring a single pole switch into a 220v circuit rlmorgan Electrical 38 10-15-2008 07:59 PM
Using 14/2 wire on 20 amp circuit mohairy Electrical 1 12-29-2007 06:26 AM
So lost - electrical requirements please help lapsis9 HVAC 4 12-20-2006 08:09 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.