Splicing different gauge wire

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  #1  
Old 01-18-13, 05:11 PM
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Splicing different gauge wire

Is it OK to splice two 14 gauge copper (standard household wire ) in a junction box (in the house) with marrettes to a 10 gauge wire? This 10 gauge connected to main breaker panel 30 amp .The two outdoor rated 14 gauge wires go through an underground conduit to the garage to a two 15 amp breaker box in the garage about 30 feet away?
 
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  #2  
Old 01-18-13, 05:28 PM
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No; the #14 is too light for the 30a breaker.
And making the connection would be very difficult, though otherwise legal.

A house I used to own had 3 #12 wires connected to a 50a breaker. If one shorted it could easily have started a fire without tripping the breaker.
 
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Old 01-18-13, 06:23 PM
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Everything in your post is in violation and especially in the first case dangerous. A #14 wire must be protected by a 15 amp breaker. You can not run two power sources to the garage. I suspect what you are trying to do is twin the wires because you don't want to buy the correct size wire. You aren't allowed to do that for wires that small.
 
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Old 01-18-13, 07:58 PM
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If the 15A wires are the ungrounded conductors on a multiwire circuit (e.g. the red and black wires on a 14-3 cable), then you can replace the 30A breaker with a double pole 15A breaker (both poles tied together).
 
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Old 01-18-13, 07:59 PM
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There is nothing wrong with joining 2 #14s to a #10 wire, as long as you use the correct size wire nut
AND.....as long as the #10 wire is protected by a 15 amp breaker or fuse. BUT.....the OP has described something that is not only unsafe and a fire hazard, but a code violation as well.

Mod Note: Post referred to has been deleted because it seems to support unsafe practices.
 
  #6  
Old 01-19-13, 10:40 AM
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10 gauge spliced to two 14s

Thanks everyone for advice yesterday.How about this way.---

Splice the two 14s to the 10 in a junction box where the conduit comes through the back wall.Connect the 10 to a 15 amp breaker in main panel for house ? The garage is at back of house.Conduit about 30' long .The 10 gauge runs through enclosed ceiling to main breaker at front of house about 25'.And do I need to have a separate breaker in the garage to meet code?
 
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Old 01-19-13, 10:43 AM
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I am not sure if the CEC requires a disconnect.
 
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Old 01-19-13, 01:44 PM
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What are trying to accomplish by doing this?

What wires will be in each conduit (number, color and size)?

What will be connect to the wires at the garage?
 
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Old 01-20-13, 08:43 AM
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Just want to install outlets and lights .Will just run some simple tools from the outlets .Nothing heavy duty.
 
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Old 01-20-13, 08:54 AM
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Ok.
Originally Posted by nashkat1
what wires will be in each conduit (number, color and size)?
.
 
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Old 01-20-13, 09:01 AM
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Yes. You can do what you suggest in your 2nd proposal as long as the breaker is changed to 15 amp. You should also tag the #10 wires so that somebody later on in life does not change it back to a 30 amp. Splicing the #14 and #10 wires with a nut is fine as long as it is rated for the combination of wires.

A better option, IMO, is to install an fused pullout disconnect like you would use for an air conditioner, or install a small sub panel, where it comes out of the back wall. Then you can run your branch circuits from the 30 amp feeder (fused to 15 amp) and you would some spare capacity for later.
 
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Old 01-20-13, 02:10 PM
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Thanks.- I have the sub panel with two 15 amp breakers.I'd like to do your second preferred suggestion .Putting the sub panel at the back wall where the two wires go through conduit to garage.Is that to code ? I read somewhere that all boxes have to be together in one location?
 
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Old 01-20-13, 02:30 PM
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Unless the conduit is metal there should be three wires, a hot, a neutral, and a ground. Or did you really mean two cables? There shouldn't be two cables from the main panel to the sub panel though. Can you clarify what you mean?

What you should have if it is 120 volts only is a black wire, white wire. and a green wire, (if PVC conduit) through the conduit to the subpanel. Since the subpanel is almost certainly intended for 120/240 only half of it will be used. You will need to add a ground bar bonded to the case and isolate the neutral bar. If this is a detached garage you will also need an eight foot ground rod.
 
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Old 01-20-13, 02:47 PM
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I see you'er in Canada. The info here is from the US NEC which is very close to Canada's electrical code but there are some differences that I may not be aware of. Be sure to check with your local authorities.

Services are required to be grouped in the same location, sub-panels are not. As Ray mentioned, you should have 3 wires unless the conduit is one that is listed as a ground, such as EMT. If you are not sure, or it is a conduit not listed for ground, you will need to add a ground wire to your run. Also, if you do not have a white wire (which is likely for a 30 amp circuit) you would need to add a white for a neutral.

Also, as Ray mentioned, your sub-panel is likely split for 120/240 volt use. You can either connect two hots and a neutral for 120/240 volts, or only one hot and a neutral for 120 volt only. You can add a jumper from the hot to both lugs to energize all spaces of the sub-panel. You won't have 240 volts but at least you can use all the spaces.

Of course all equipment needs to be rated for the location you intend to install them in.
 

Last edited by Tolyn Ironhand; 01-20-13 at 06:41 PM.
  #15  
Old 01-20-13, 06:38 PM
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Thanks for the help guys much appreciated .
 
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