What size wire is code?

[pioneergal]

We have trenched 200 ft.from the 200 amp service pole to our 16 X 24 storage building.

I would like to have a few wall plugs and a light inside, an outside light and maybe a freezer inside.

DH had thought about 1/0 but was concerned that it would be overkill plus the price is expensive.

Do we have an alternate choice of wire that won't break the bank?

We just doesen't like spending mega bucks on a building that won't be used on a daily basis. 

[glenn kangiser]

Wire size calculator shows #4 for 20 amps.   200 feet one way.

http://www.gorhamschaffler.com/wire_size_calculator.html

That should easily carry a freezer and extras.

A more complicated calculator considering code better, but result is the same.  You must fill in the second step on this one and increase to #4 to get acceptable drop(2.1%), but #6 is only 3.3%

http://www.electrician2.com/calculators/wireocpd_ver_1.html

[MountainDon]

Using my electrical designers calculator with the 200 ft distance and keeping to  maximum of 3% voltage drop, my calculator indicates the following wire sizes for different loads:

15 amps 6 AWG

20 amps 4 AWG

30 amps 3 AWG

40 amps 2 AWG

60 amps 1/0 AWG

[bayview]

  I always go a little overboard. . . In case I want to add other circuits later on . . .

[phalynx]

I'm not so sure that calculator works well.  I put in 200 amps at 2' and it says I can run #14......    Not me...

[glenn kangiser]

Looks like it has it's limits -- and I don't know where they are.  Found it on the net.

Looks like the range we are talking about matches the other calc. and Don's though... but good point.

[MountainDon]

All these calculators are based on the same principles, the same mathematic formulae, the same electrical resistance laws, etc. I believe that when working with 'normal' distances they provide credible results.

My calculator is a stand alone computer program that retails for a crazy price, aimed at professional electrical designers. It'll do things I have no idea about. I didn't buy it, but hit upon a completely innocent way to make it work past the trial period.  <insert halo smiley here>

http://www.edreference.com/

[Willy]

Wire size calculator shows #4 for 20 amps.   200 feet one way.

http://www.gorhamschaffler.com/wire_size_calculator.html

That should easily carry a freezer and extras.

A more complicated calculator considering code better, but result is the same.  You must fill in the second step on this one and increase to #4 to get acceptable drop(2.1%), but #6 is only 3.3%

http://www.electrician2.com/calculators/wireocpd_ver_1.html

Yes #4 alum is OK but it would be better to run it #4-#4-#4 and you could feed it with 240 volts and split it at the building in a panel to have 2 -20 amp 120 volt circuits with a combined load of 40 amps total. The neutral will be fully loaded when only one side is at 20 amps but if both sides are drawing 20 amps the load will be zero amps on the neutral. Due to the long run the neutral needs to be full size since it can be loaded up to the full load very easy with only 2 circuits. Now that is what I would do if I wanted to run motor loads, ballests ect off the circuit. If you drop the wire size down to #6 AL you can carry a full 15 amps each side (2-circuits 30 amp total load) with out voltage drop problems besides a regular house 120 volt plug outlet should not be loaded up over 15 amps anyways unless you have a 20 amp rated outlet. The branch circuit should be rated at 125% of the load it is going to carry as to not over heat the breaker or wiring. Mark

[glenn kangiser]

Sounds good, Mark -- what about a ground -- Pull from the main box ?  Smaller?  I only do enough wiring to be dangerous.

[Willy]

Sounds good, Mark -- what about a ground -- Pull from the main box ?  Smaller?  I only do enough wiring to be dangerous.

Since it is a seperate building the grounding is needed to be made at the building by 2 - 8 ft ground rods and the neutral bonded inside the panel to the #6 ground wire going to the ground rods. The small panel should also be bonded to any metal plumbing inside it. As long as there isn't over 6 breakers in the panel you won't need a main disconect. Mark

[glenn kangiser]

Thanks a million, Mark.  I've always been a bit vague on the time that was necessary - haven't read the electrical code in years.

[Willy]

Thanks a million, Mark.  I've always been a bit vague on the time that was necessary - haven't read the electrical code in years.

Grounding and Bonding are 2 sections of the NEC Electrical code that is realy very hard to understand. Both are related but very different. Bonding is when you connect the metal parts of non electrical stuff to the panel so in case they become energised they will trip the breaker or bleed off the electricity to ground. Grounding is when you connect electrical items metal parts to the ground rod. Now bonding the Neutral to the Ground helps make the neutral better and adds to all the other grounds in the power grid to make it a good neutral. The Grounding System is made of several things. It can be Ground Rods in the Earth, Re/Bar inside Concrete or a ground brought from another panel that is the main panel and going to a sub panel in the same building. This is when you isolate the Neutral from the Ground after it leaves the Main Panel. You do this to a Mobil Home also to keep the neutral seperate from the ground inside the panel that is in the Mobil Home. This gives electrical shorts a path back to the Main Service(Meter Location) Disconect to trip the breaker/bleed to ground instead of energising the metal frame and tin on the trailer! They do not want you getting killed grabing the metal door handle on a trailer standing in the rain tring to get in!! When you take power from the main building and go to another building like a shop the panel in the new building becomes a little service and needs it owns ground rods installed and all metal pipes Bonded to it. I hope I said this in away you can understand the code a little better. Now what I said in a few words is told in the NEC with probley 100 pages of print!!!! Mark

[glenn kangiser]

That helps a lot, Mark. Thanks.