wire size too large?

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dwagener

Member
Location
coarsegold,CA.
this question has come up twice in the last couple of months,once for led lighting and once for hvac split system control wiring.for the led wiring I cannot remember the reason because it did not make sense to me that you could not increase the size of the wire for proper lighting.the hvac tech was having problems with his units working properly and said it was because we had used 12 gauge wire instead of 18 or 16 gauge which he recomended.has anyone ever heard of this?just curious
 

charlie b

Moderator
Staff member
Location
Seattle, WA
Occupation
Electrical Engineer
Sounds like pure nonsense to me. The only effect a larger wire would have on the operation of the circuit would be to reduce (by a very small amount) the voltage drop along the conductor. That will not stop a light or an HVAC system from working properly.
 

bphgravity

Senior Member
Location
Florida
I agree with Charlie.

I cannot think of a single application where the installation of conductor larger than required would result in a hazard or create a functionality problem. Other than the potential of problems terminating a larger conductor than necessary and the potential greater cost of a larger conductors, you would only benefit from the larger conductor sizing.
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
Pure non-sense. A person who claims this is not very knowledgeable on the subject.
 

charlie b

Moderator
Staff member
Location
Seattle, WA
Occupation
Electrical Engineer
In addition, an HVAC person who claims this is the reason his unit is not working properly is merely trying to pass the blame to somebody else, so he does not have to pay for the repairs to his own equipment.
 
I agree that the wire size has absolutely nothing to do with this. With the exception that perhaps the wire terminals for the connections might not support larger wire, there's nothing wrong at all.

Ironically, I got a call from a hotel owner who was told that the control wiring for his top-floor HVAC systems was too small. The place was a year old and the original installers had used typical brown-jacketed thermostat wire for these runs. The longest one was about 30 feet. His HVAC 'technician' insisted that we replace these runs with 12 gauge minimum. Yeah, OK.
 

Electric-Light

Senior Member
It's entirely possible someone used stranded 12AWG and in the process of making it 18 AWG for the purpose of connecting to thermostat, some whiskers stuck out and shorting to each other.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
For LED lighting we use typically use #12 MC cable for the loads spliced to a the driver which has #20 AWG conductors. Oh and it works just fine. :roll:
 
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