wire gauge question

[Digital2k2]

I added a 15 amp circuit breaker to run a dehumidifier that draws 6.6 amps so it wouldn't overdraw from an already loaded circuit.

It took 50 feet of 14 gauge wire.. I'm thinking it might have been better if I used 12 gauge since this thing runs a lot during the summer and there would have been less line loss.

Anyone with experience in wiring know if 12 gauge would be worth it considering the 50ft length and that there's a 24/7 load of 6 and a half amps on it?

I'm not sure if there's some formula to figure out optimum wire gauge giving the length of wire and load? If it were just a 25 foot run I wouldn't think twice about it.

Thanks for any input

 

[Pablo]

We've been over this 2-3 times here.

I'll just leave it at this: Use 12awg wire. The cost is slightly higher, but it's just better in the long run. You can still use a 15A breaker if you like, or do it right with a 20A breaker.

 

[MGregoir]

14 gauge wire would only allow for a 2% voltage drop over that course of 50 feet at 6.6 amps. 12 gauge is about 1.5%. That's very good, and basically overkill. I wouldn't worry about going to 12 gauge wiring to the point of going back and changing it.

 

[XS650]

Considering it's installed I wouldn't bother changing it.

You can find tables that recommend wire gauge vs load and distance.

Personally, I wouldn't even consider installing a new 15 Amp 14 gauge circuit. The additional cost for 12 gauge is small and some time in the future, the 12 gauge may be needed for something else.

 

[Al]

I never run anything except 12 gauge-period.

One other thing, buy it in no less than 250 ft. rolls.

 

[oilyriser]

Starting current will be about 15A for that dehumidifier.

 

[tom slick]

you can run up to 85 feet of 14awg with a 15 amp 24/7 at 100% load and be within NEC guidelines. At 50 feet a 15 amp load only needs 16awg, but NEC dictates 14awg.

bottom line, you are at overkill with 14awg.

 

[Papa Bear]

14 gauge and conventional oil ...nothing more is needed.

Maybe "wanted" but not needed.

 

[Digital2k2]

Originally Posted By: MGregoir
14 gauge wire would only allow for a 2% voltage drop over that course of 50 feet at 6.6 amps. 12 gauge is about 1.5%. That's very good, and basically overkill. I wouldn't worry about going to 12 gauge wiring to the point of going back and changing it.


Interesting.. so about .5% difference in voltage drop. I wonder if say over a 5 year period there would be a difference amounting to a number of kilowatt hours in energy consumption from line loss?

This is a 20 year old box and all I could find for it was a 15 amp breaker after looking for a long time. Felt like I struck gold when I snapped that thing in there and it fit like it was made just for that box. Since it's only there for running a dehumidifier, when I bought the line I just wasn't thinking about voltage dropping even 2%

.

The funny part is I got the UF-B outdoor rated cable because the insulation was thicker around it, but didn't even think to buy 12 gauge wire.. (it runs from the garage into the crawl space)

I was wishing I'd thought of that when checking the voltage drop with the dehumidifier running.

But hey it's still better than that other outlet I had it running off of down there that 1/3rd of the lights in the house are on also.
If we plugged the vacuum cleaner into the wrong outlet it'd trip the breaker haha.. 12.5 amp vac, 6.6 amp dehumidifier plus a couple hundred watts of lights = bad for 15 amp circuit.

<we need one of those for a house =p

 

[oilyriser]

I may be wrong about the surge. I just checked an 8-yr old dehum, and it takes 8.5A starting and 7.3 running. That's using one of those cheap digital watt meters, and I'm not sure how many samples per second those things do.

 

[The_Jeff]

You can count on an inrush current of 2-3x rated when starting an electric motor, but the wiring and breakers can, and are in fact designed to, take it.

 

[TallPaul]

14 gauge is fine for that application.

Yeah, running all 12 gauge is a great idea, but I hate the pain in the neck making connections with the thicker wire. 14 gauge is easy to connect to devices like switches etc.

 

[The_Jeff]

True, just use the side screws-- those backstab outlet and switch connections are bad news.

 

[TallPaul]

Yeah, I never use the backstabs.

 

[XS650]

Originally Posted By: TallPaul
14 gauge is fine for that application.

Yeah, running all 12 gauge is a great idea, but I hate the pain in the neck making connections with the thicker wire. 14 gauge is easy to connect to devices like switches etc.


That's good if you are a builder trying to squeeze the last few cents out of materials and labor costs.

If I'm wiring something for myself, I'll take the extra time and cost for a 12 gauge circuit every time. Maybe if I was running a circuit from an already overstuffed box...

 

[Papa Bear]

Perhaps in the kitchen where we use frying pans and microwave ovens but even there the 14 ga is fine for 15A circuits. The rest of the house with CF bulbs and LCD tv's would never approach 14 ga max threshhold. Anything more than 14 ga really isn't necessary.

We buy that expensive "monster" cable to wire our stereo speakers while the wiring inside the speakers is lucky to be #22.

But being human we do need to get the warm fuzzies by overdoing things once in a while.

 

[XS650]

Originally Posted By: Papa Bear


But being human we do need to get the warm fuzzies by overdoing things once in a while.

I hope you aren't accusing anyone on BITOG of ever getting obsessive.

 

[Papa Bear]

All I can say is the high price of Lithium is affecting the cost of my meds...

 

[Pablo]

That's not funny.