Looking for electrical info / help

Gator

Gator

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I have a 12 X 16 mini barn that functions as a garage for my motorcycle and a hobby / workshop. I get power from an outside outlet in the pic below, just to the right of he white chairs using a standard 3 prong drop cord. From there it branches off into two different power strips inside the building.

What I have for hardware in the building is -
two 4 ft LED lights
small table top drill press
desktop light with magnafier
very small grinder / buffer
charger for cordless drill
pancake air compressor
Battery Tender
Work Sharp knife / tool belt sander-tool sharpener
box fan

I never have all of the items turned on at once. There's nothing that requires 220 volts.

What I want to do is run a permanent power source from the breaker box on the right side of the picture to the building so I can stop using the drop cord. From the breaker box to the corner of the kick-out is 8 feet. From that corner to the building is 26 feet.

There is an empty 20 amp breaker that was used for a swimming pool pump we no longer have. I have a general idea what needs to be done but when it comes to electricity I know my limitations.

The questions I know to ask are-
What gauge wire do I need?
Does it need to go through a conduit?
Is the 20 amp breaker sufficient?
Is a small breaker box needed inside the building

Fell free to tell me what I don't know.


Gar1.jpg
 
If it were me I'd take 30 amps into a 2 breaker box. The wire one side on 1 breaker and the other side on another.

10g wire is good for 30a. You can get direct burial 10g wire. No conduit needed that way
 
You can get direct burial cable as mentioned above. Need to consult the NEC tables, but off hand, 12 gauge is good for 20Amps but I don't know if that still applies to a burial application. If I recall correctly, the burial depth is 18" through ground, not under a patio or driveway. If you do run it in conduit, still use a direct burial or "wet" type cable as it will get water in it. It doesn't sound like you are planning on running anything that would be considered a continuous load (on more than 3 hours) except generalized lighting. You also need to take into account the temperature rating of the breaker / lugs. Unless otherwise specified assume 60 deg. Note also that cable type UF (underground feed) is in the 60 deg column, where as a THHW or XHHW (W meaning Wet) in a conduit could push a higher ampacity if the lugs support it.

Are you planning on running this as a branch circuit off the breaker or are you going to run it as a feeder, meaning into another breaker? If you do, be sure to keep the ground bonded.

Here is a page discussing calculating the wire sizing and and also has a chart that shows 20A for 12 gauge. I found an older NEC table that was higher, but it had a ** note for 15A / 20A protective devices.

https://www.electricallicenserenewa...cation-Courses/NEC-Content.php?sectionID=32.0
 
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When it comes to electricity remember one thing. Overkill. In other words plan for more than you need because your plans will change. Circuits are not to be loaded more than 80%. Or at least that was the rule way back when. It may be different now.

If you really want to get technical you can figure current draw on all the items that you use and go from there. If not. "Overkill".

If it was me I would scrape the 20 amp breaker to begin with and put at least a 30. You said you don't need 220 but run it anyway. The benefit is you will have it plus you can split things up and have them on different circuits.

Distance is another thing. 26 ft. to the building and 8 ft.to the corner is 40 ft. Add at least another 6 ft. from the panel to the ground plus where ever it has to go inside your building. All that translates into voltage drop. There are charts to figure voltage drop on a certain size wire over a certain distance. On 30 amp you need 10 gauge wire ( I think, It has been along time since I worked in electrical field so codes may have changed.)

Here is a calculator. Drop in 12o v. ,10 gauge wire cooper wire(don't use aluminum I don't care how good a deal you get on it) , at 30 amps and 50 ft. and you lose 3.73 v. Change the distance to 75 ft.and the drop goes to 5.59 v.

http://wiresizecalculator.net/calculators/voltagedrop.htm

Yes on the box in the building. You wouldn't want something stupid to happen and have to run to the house to shut of the juice.

I will stop there now since between me an the others I am sure you are totally confused. :p
 
LeeMajors said:
If it were me I'd take 30 amps into a 2 breaker box. The wire one side on 1 breaker and the other side on another.

10g wire is good for 30a. You can get direct burial 10g wire. No conduit needed that way
Click to expand...

So if I go to a 30 amp breaker in my main electrical box is it as easy as just taking out the 20 amp and plugging in a 30 amp?

'
 
noway2 said:
You can get direct burial cable as mentioned above. Need to consult the NEC tables, but off hand, 12 gauge is good for 20Amps but I don't know if that still applies to a burial application. If I recall correctly, the burial depth is 18" through ground, not under a patio or driveway. If you do run it in conduit, still use a direct burial or "wet" type cable as it will get water in it. It doesn't sound like you are planning on running anything that would be considered a continuous load (on more than 3 hours) except generalized lighting. You also need to take into account the temperature rating of the breaker / lugs. Unless otherwise specified assume 60 deg. Note also that cable type UF (underground feed) is in the 60 deg column, where as a THHW or XHHW (W meaning Wet) in a conduit could push a higher ampacity if the lugs support it.

Are you planning on running this as a branch circuit off the breaker or are you going to run it as a feeder, meaning into another breaker? If you do, be sure to keep the ground bonded.

Here is a page discussing calculating the wire sizing and and also has a chart that shows 20A for 12 gauge. I found an older NEC table that was higher, but it had a ** note for 15A / 20A protective devices.

https://www.electricallicenserenewa...cation-Courses/NEC-Content.php?sectionID=32.0
Click to expand...


I'm not quite clear on your question. I think what I should do is to pull power from the main box and install a smaller breaker box in the storage building. No idea what you mean by keeping the ground bonded.

.

.
 
LeeMajors said:
Yes. If you buy the supplies and dig the trench ill come by and show you whats needed
Click to expand...

That's a pretty awesome offer. It may be a while on this, got a few other projects going on. I may be in touch sometime in the future.

.
 
Gator said:
I'm not quite clear on your question. I think what I should do is to pull power from the main box and install a smaller breaker box in the storage building. No idea what you mean by keeping the ground bonded.
Click to expand...

In all fairness, there are plenty of inspectors who don't know what keeping the ground bonded means, either. And many people don't use the terminology correctly or consistently, which leads to confusion.

If it's a simple feed from a circuit breaker in the main box to the shed, then the ground is properly bonded because everything supplied from the main box breakers is bonded through the main box. (Presuming, of course, that the original panel was properly installed.)

If, however, he's NOT using a breaker to supply power to the shed and instead is splitting power off before the breakers in the main box to feed a small breaker box in the shed, the bonding is still something that has to be dealt with. Sub panels, which are connected to a bonded main panel, cannot also be bonded. The bonding is ONLY through the main panel. The reason for this is to prevent establishing a bond circuit between the two panels which could become current carrying under fault conditions.

For some reason, some professionals in the field don't/can't understand what bonding is and what it does...and unfortunately, some inspectors in the field are likewise ignorant on this. Bonding is there for a very important safety reason, which is essentially to conduct faults to ground. And it's vital that the bond NOT become part of a normal current carrying circuit which would result in the bond being energized outside of fault conditions. Neutral, for example, is intentionally part of a current carrying circuit. The bond is not.
 
If you’ve been running everything off a drop cord with no issues, a 20 amp circuit with receptacles on #12/2+Ground direct burial “romex” will be sufficient and the simplest way to go.

Accepting offers of help is the better way to go.

(Warning: you shouldn’t put standard 15/20 amp receptacles on a 30 amp breaker - you’ll need a mini breaker box in your shed.)
 
@amnesia and I did a similar project at his old place a couple of years ago.

Lots of good advice thus far in this thread.

If it were me, I would....

1. trench in two pvc conduits from the house to the outbuilding. I would use 1” for one run and 3/4” for the other. The 1” would be used for pulling your power wires. It’s large enough so that if you wanted to increase your power service to 60a in the future all that you would have to do is pull new wires. The second conduit would be available to pull Ethernet for security cameras, coax for Tv, etc.

2. At a minimum I would install a 240VAC 30a service.

3. I would install a breaker box in the outbuilding rated for at least 60a.

Conduit is cheap. Using it instead of direct bury wire provides you with more flexibility in the future. And in my opinion 30a 240 is the minimum power available that I’d want. Your compressor will require a 20a circuit just for itself.
 
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one more thing to consider- you'll probably want two circuits in your shop with some lights and outlets on one and some on the other. That way if you're running a saw or other power equipment and the breaker trips, you won't be stuck in the dark with a spinning blade.
 
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