Wire Size, Bigger Always Better or at Least OK??

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  #1  
Old 02-27-05, 07:34 AM
Jwichman
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Wire Size, Bigger Always Better or at Least OK??

Finishing my basement project. I have 1 existing light circuit with 10 statndard incandescent fixtures on it. Four fixtures in the garage that won't change, two outside that won't change, and four in the basement that will go away and be replaced with four incandescent fixtures and three 75W max recessed fixtures.
Prior tearing out the four old fixtures, placed my new roughin boxes and ran all new 12ga wiring from the new boxes to new switches and the to a new junction box. I then killed the 20amp breaker at the panel and ran the existing feeder to the new junction box to tie into my new light circuits. At this time I found the existing feeder wire to be 14ga, not 12 as I initiially though. Thus I have a 20 amp breaker and 14 ga wire feeding my basement, then 12ga wire feeding my light fixtures. Is this OK or do I have to replace the new 12 ga with 14?

Thanks,
 
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  #2  
Old 02-27-05, 09:08 AM
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This is NOT okay. It is a fire hazard.

Replace the 14 gauge wire with 12 gauge, or replace the 20 amp breaker with a 15 amp breaker.
 
  #3  
Old 02-27-05, 09:20 AM
Jwichman
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Replacing the 20amp breaker with a 15amp will definetly be the easiest to replace. Once that is done is there anything wrong with mixing the 14ga wire and the 12ga wire (12ga is at the end of the run)?
 
  #4  
Old 02-27-05, 09:46 AM
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It is 'nice' to mix wire sizes, but it is neither required nor a safety issue to mix wire sizes as long as the circuit is protected for the smallest wire. So if you have a mix of 12ga and 14ga wire in a branch circuit, and you protect it with a 15A breaker, then you are fine.

One of the reasons that people don't like mixing wire sizes is that if things get changed in the future, some of this 12ga wire might get connected to a 20A circuit, with the installer not noticing that this also connects 14ga wire.

-Jon
 
  #5  
Old 02-28-05, 05:56 AM
Jwichman
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I replaced the 20 amp breaker with a 15amp, a pretty simple fix. However once I got into the panel I found what appeared to be several 14ga wires landed on 20amp breakers. Didn't find any gauge markings on the wires themselves to tell for certain, but eyeballing they looked like 14ga to this rookie. Anyway to tell for certain the gauge of the wire? Is there any circumstance where 14 gauge wire is suitable for a 20amp circuit?

I also found a small transformer landed on one of the breakers and just hanging inside the cabinet by it's leads. This particular breaker already had a circuit wire landed on it, and the transformer was the second wire landed there. Would this be for doorbell? Should ther xformer be located inside the panel? I'm sure it ought to be mounted somewhere rather than just hanging by it's leads?? Can you land more than one wire on a breaker, even if it is a low voltage xformer?

Thanks for all your help.
 
  #6  
Old 02-28-05, 06:41 AM
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If the circuits in question control residential lights or receptacles then 20 amp circuit breakers are not allowed for 14 gauge wire. Look at the cable where these wires exit. Is the cable marked?

A transformer should not be hanging loose anywhere. It should be mounted to the outside of the panel, or on a separate junction box somewhere.

Some circuit breakers allow for two wires to be connected to them. Some don't. Does the breaker have positions for two wires?
 
  #7  
Old 02-28-05, 07:08 AM
Jwichman
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Moving the transformer outside the panel will be easy enough. There is a recepticle mounted on the side of the panel to which I should be able to mount the transformer to and parallel from for power.

There was only one lug on the breaker to which to wires were landed. My guess is that it is not allowed?

All of my breakers prior to installing the 15 amp are 20 amp or gretaer. Most of the breakers are 20 amp for the majority of the circuits. From a prior post I was told that 15 amp rated recepticles can have a 20 amp breaker however 14 ga wire is not acceptable in this situation?
 
  #8  
Old 02-28-05, 07:32 AM
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"There was only one lug on the breaker to which to wires were landed. My guess is that it is not allowed?"

I would agree, not allowed.


"From a prior post I was told that 15 amp rated receptacles can have a 20 amp breaker however 14 ga wire is not acceptable in this situation?"

Correct. 15 amp receptacles can be on a 20 amp circuit breaker. However, a 20 amp circuit breaker MUST have 12 gauge (or larger) wire. By larger I mean smaller gauge number, which is physically larger diameter wire.
 
  #9  
Old 02-28-05, 07:35 AM
Jwichman
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Thanks, for the info. I will have to do some further investigation on the actual wire sizes in my panel.
 
  #10  
Old 02-28-05, 09:32 AM
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One simple way to distinguish 12 gauge wire from 14 is to remove it and try to bend it with your thumb and finger on the bare part. (Of course you will make sure this wire is de-energized.) You will find the #14 wire fairly easy to bend, and the #12 almost impossible. No tools allowed for this test - you get the right tool and amost anything is easy to bend.

Modern wiring should always be marked on the insulation. Older wire, you're on your own. FYI, if you have any knob & tube, it is almost always #14.

Juice
 
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