AC Wiring: 14 Gauge/3 Extension vs. 14/3 Romex & Box


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Old 05-30-20, 09:03 AM
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AC Wiring: 14 Gauge/3 Extension vs. 14/3 Romex & Box

In terms of safety, is there any practical difference between running a 14 gauge (grounded) extension rated for 15 Amps, verses wiring 14 gauge Romex and mounting an outlet box near the load (in my case, a small dehumidifier)?

I see warnings about extensions getting hot, or being a shock hazard, but if the gauge is the same, what difference does it make? (Other than bonehead factors like tripping over an extension, etc.)

Is this a matter of stranded wire vs solid copper in the Romex? Is there in fact a difference? Thanks.
 

Last edited by krisak; 05-30-20 at 09:42 AM. Reason: clarity
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Old 05-30-20, 10:38 AM
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Hi, if you are planning on the extension cable to be permanent install the itís not allowed, gauge for gauge there is no difference,if thatís what youíre asking.
Geo
 
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Old 05-30-20, 10:45 AM
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Wire size being the same the only difference would be the insulation around the wires. The wires in Romex (NM-b) are THHN which insulation is rated at 90C degrees (however, Romex can only be used at the 60C degree). You would have to look at the rating on the extension cord jacket to see what it is rated at.

If that cord is also rated at 90C then they are equivalent and there is a minimal risk using the cord on a temporary basis.
 
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Old 05-30-20, 11:16 AM
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I've seen lots of damaged extension cords. Not just the wires but the ends too. Why do so many have black scorch marks on them? Many others have the ground pin broken off, mostly intentionally.
 
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Old 05-30-20, 12:04 PM
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Electrically there is no difference. However the extension cord would be subject to damage. If this is more than a temporary use you should install the NM in wall with the receptacle.
 
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Old 05-30-20, 06:44 PM
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Yes, that's what I meant by boneheaded. My brother had a habit of cutting off grounding pins, or using grounding adapters without connecting the ground. (Come to think of it, I've never seen one used correctly in the wild.)
 
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Old 05-31-20, 04:49 AM
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I see warnings about extensions getting hot, or being a shock hazard, but if the gauge is the same, what difference does it make? (Other than bonehead factors like tripping over an extension, etc.)
I think you captured a large percentage of the population with the 'bonehead' comment. Though, more often, it's probably someone just not understanding how electricity works. You and I understand that a dehumidifier or space heater would need to use a heavy-duty, well-made, 14ga extension cord. But how many others would plug a 1500w space heater with an 18ga zip cord extension. Possibly run behind a bookcase which is pinching the wire? Oh, and the female end of the cord was made in china and is a bit off, so doesn't have enough spring to hold in the plug securely.
 
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