Can I connect a #6AWG copper conductors to 20A1P breaker?

[ElectricNewEngland]

I have two Gas Unit Heaters 1/2HP at 120V, which equals 9.8amps each. The farthest heater is 225 feet away from the 120V panel feeding it. Using #8 copper conductors gives me a voltage drop of 2.9%. My company doesn't want to go higher than 3.0% voltage drop, so I want to use #6 copper conductor which will reduce my voltage drop to 1.7%.
Can I use the #6 copper wire with a 20A1P breaker? If not, can I use #8? How would I even know how to look this up? Is there a table in the manufacturer's catalog somewhere? We use Square D breakers, if that helps.
Thanks.

 

[hillbilly1]

If the breaker lugs are too small to accept the #6, there are several ways you can make this work, the easiest is to splice a smaller wire to it in the panel, or set a j-box near the panel and downsize the wire from there, or use a crimp type reducer just to name a few ways.

 

[roger]

If you do not have a SQ D digest available you can go to their web site and get this information. SQ D QO breakers up to 30 amps will accept up to a #8, the best solution would be to do as Hillbilly1 says and splice smaller conductors on to the #6 in the panel.

Roger

 

[Smart $]

If #8 will give you less than 3% drop, why do you want to use #6???

 

[ElectricNewEngland]

If #8 will give you less than 3% drop, why do you want to use #6???

Thank you to all who responded so far. I was thinking of using the #6s just because using the #8s 2.9% voltage drop was very close to the company maximum voltage drop of 3.0%. If they install the conductors with any slack, the home run length becomes longer, which may bring the voltage drop over the 3.0%

 

[G._S._Ohm]

3%

3%

and not 3.0%.

In a tight spot you can debate significant figures.

3, that is 3 x 10^0, means between 2.5% and 3.4%.
3.0, that is 3.0 x 10^0 or 30 x 10^(-1), means between 2.95% and 3.04%.

Also, #6 is 1.3 ohms per, #8 is 2.0. This is a 50% increase and nobody makes 7 AWG. Close enough.

And nobody should report their height as 69.13". It overstates accuracy and precision and measurement repeatibility.

 

[hillbilly1]

Don't forget about startup current since its a motor load, many people undersize their wire because they don't take into account for startup amperage. I always bump it up a little to allow for that.

 

[Smart $]

Thank you to all who responded so far. I was thinking of using the #6s just because using the #8s 2.9% voltage drop was very close to the company maximum voltage drop of 3.0%. If they install the conductors with any slack, the home run length becomes longer, which may bring the voltage drop over the 3.0%

How did you arrive at 2.9%? I'm only getting 2.5% with the values provided.

 

[tkb]

If you are going to upsise to #6 for your current caring conductors, don't forget that the equipment ground needs to be up sized to a #6 also.

 

[mlnk]

grounding conductor is based on cir. breaker size....use #12

 

[roger]

grounding conductor is based on cir. breaker size....use #12

Not true, see 250.122 (not the table)

Roger

 

[tkb]

grounding conductor is based on cir. breaker size....use #12

Not always. When you upsize ungrounded conductor you have to upsize the grounding conductor.

250.122 (B) Increased in Size. Where ungrounded conductors are increased in size, equipment grounding conductors, where installed, shall be increased in size proportionately according to the circular mil area of the ungrounded conductors.

 

[infinity]

Use the #6 and splice on a #12 or #14 next to the breaker.

 

[Little Bill]

If you are going to upsise to #6 for your current caring conductors, don't forget that the equipment ground needs to be up sized to a #6 also.

You don't have to up-size the EGC to the size of the ungrounded, just the same proportion/ratio.

grounding conductor is based on cir. breaker size....use #12

If you up-size the ungrounded, you also have to upsize the EGC

Not always. When you upsize ungrounded conductor you have to upsize the grounding conductor.

250.122 (B) Increased in Size. Where ungrounded conductors are increased in size, equipment grounding conductors, where installed, shall be increased in size proportionately according to the circular mil area of the ungrounded conductors.

 

[tkb]

You don't have to up-size the EGC to the size of the ungrounded, just the same proportion

You would on a circuit with 12 or 10 ungrounded conductors.
The grounding conductors are the same size as the ungrounded so proportionally it would be the same size.

 

[iwire]

You don't have to up-size the EGC to the size of the ungrounded, just the same proportion/ratio.

Correct but in the case of 15, 20 & 30 amp circuits the ratio is 1 to 1. So 6 for the ircuit inductors means 6 for the EGC.

 

[don_resqcapt19]

...And nobody should report their height as 69.13". It overstates accuracy and precision and measurement repeatibility.

Are you saying we can't measure to the nearest 1/8 of an inch? (69.13 = 69 1/8 rounded up) My measuring devices are marked to the 1/16s.

 

[Little Bill]

You would on a circuit with 12 or 10 ungrounded conductors.
The grounding conductors are the same size as the ungrounded so proportionally it would be the same size.

Correct but in the case of 15, 20 & 30 amp circuits the ratio is 1 to 1. So 6 for the ircuit inductors means 6 for the EGC.

I know and understand that. I was speaking to the statement made that sounded like they thought you always upsize the EGC to whatever size the ungrounded conductors were.
I was just trying to clarify the EGC was only upsized proportionally.
But yes, in the case of the smaller OCPD (15-30A) they would be the same.

 

[G._S._Ohm]

Are you saying we can't measure to the nearest 1/8 of an inch? (69.13 = 69 1/8 rounded up) My measuring devices are marked to the 1/16s.

No, it's a different idea and depends on what you're measuring. E.g., a person's height may vary from morning to night and from week to week and so measuring it to the nearest fraction of an inch may mislead you.
Measuring a good quality yardstick, though, you can probably depend on the readings you take within 1/64".

There is another related idea.
Let's say a measurement is given as 2.4 cm, so it means between 2.35 and 2.44 and it's two significant figures.
Well, some people translate this into inches and it comes to ~0.94488. . . ", which implies you know the correct length to 1 part in 100,000. It should be reported with only two significant figures, as 0.94".

 

[infinity]

I know and understand that. I was speaking to the statement made that sounded like they thought you always upsize the EGC to whatever size the ungrounded conductors were.
I was just trying to clarify the EGC was only upsized proportionally.
But yes, in the case of the smaller OCPD (15-30A) they would be the same.

Clarification on this topic is good.

I'm constantly seeing a #12 EGC with #10 circuit conductors and a 20 amp OCPD. :rant: