Check my plan for adding wiring to backyard shed, please!

[alan_3301]

I have just had a shed built in my backyard for my hobby stuff, and I need to get it wired for electricity.
Any comments are welcome, thanks. I live in Raleigh, NC.
The shed is 12'x20' and 60' away from house breaker panel. (total length of cable run)

First step, list all electrical equipment I plan on using, right?
1. CNC Router 13 amps absolute max on 240v (typically only 5 amps with peaks up to 7 amps)
2. 120v accessories for router (computer,vacuum pump,cooling pump) (7 amps)
3. Harbor freight 2hp dust collector (20 amps per HF website)
4. bandsaw ( 9 amp)
5. 6" jointer (9 amp)
6. miter saw. (20 amp)
7. thickness planer (20 amp)
8. some kind of indoor lighting, and 1 outdoor floodlight (500w total? ~5amps?)

Now how do I arrange the circuits. Here is how I was imagining the breaker panel.
50? amp main breaker in panel
2 pole 20a breaker feeding nema6-20 receptacle for cnc
20a breaker for dust collector
20a breaker feeding 3 duplex nema5-20 receptacles
20a breaker feeding another 3 duplex nema5-20 receptacles
15a breaker for all lighting.

Does 50 amps sound reasonable for the equipment listed?
An example max load scenario for me would be cnc, dust collector, lighting, and a single extra tool at the same time (20 amps).
This would give me (max load) 13+7+20+5+20 amps = 65 amps. This would never be above 5% duty cycle.
A more reasonable estimation for 100% duty cycle would be 10amps (cnc+accessories) + 20amps (dust collector is it really 20 amps continuous??) + 5amps (lights) = 35 amps or round up to 40 amps to play it safe.

If I plug some values into a online calculator (http://www.csgnetwork.com/wiresizecalc.html) it suggests #8 copper wire for a 60 ft run capable of 60 amps @ 240 volts. If I change to 120 volts it says #6 wire. which should I use?

So, how do I decide the breaker rating, and the wire specs?
Based on my research I think I want:
50 amp breaker in house breaker panel ->
wire?? If I want 240v and 120v I need 3 conductors + ground right?
#8-3 THWN inside 1" grey pvc conduit 18" below grade.
what size for the ground wire?
inexpensive breaker panel in shed.

Anything I'm missing? Or suggestions?
Thanks for your time!

 

[pattenp]

From 30 amps up to 60 amps the equipment ground can be a #10 Cu or #8 Al. You may want to consider aluminum wire for the feeder to save some $$. You can use #6 Al for 50A. I think you should do a minimum of 60A.

 

[alan_3301]

Thanks for the reply.

I found onlline wesbell electronics. They have #6 copper THHN/THWN for .62 per foot.
so with 3 #6's and a #8 ground 60 feet each, i can get the feeder set for less than $140. Think I can beat that? Should be good for 60a then right?
Will all that pull through 1" pvc? The #6 is listed as .249" and #8 as .213"
I know it will fit, I attached a diagram. I'm not sure about airspace requirements or anything like that. Any thoughts?

Also, does anyone know where to get a retaining clip for an old ITA load center?
My house main breaker is backfed (main lug panel), and as I understand it, a clip is required for code.
I'm green at AC electrical (not sure how to pull a breaker yet, do they just pull straight out?)

 

[pattenp]

#6 copper is fine for 60A. The ground only needs to be a #10. The four conductors will fit just fine in 1" conduit.

Now the price. As an example you could use aluminum 2-2-2-4 Mobile Home Feeder which is good for up to 90A and the cost for the wire at Lowes is $1.47 a foot so that's $88. It would take at a minimum 1 1/2" conduit. You can still use a 60A feeding breaker on it if you want. That way you have wiggle room for amp expansion in the future if needed.

 

[wyliesdiesels]

A backfed breaker needs to have a retaining screw which locks it down onto the panel. I'm sure one of the other sparkies can post a pic of what it looks like as I'm on an iPhone and attachments are a pain!

And yes, breakers do just pull out but at an angle. You pull on the bus side of the breaker angling it up and towards the lugside of the breaker where its foot is that locks it into the panel back plate. AND make SURE the breaker is off before removing it!

 

[Norcal]

Thanks for the reply.

I found onlline wesbell electronics. They have #6 copper THHN/THWN for .62 per foot.
so with 3 #6's and a #8 ground 60 feet each, i can get the feeder set for less than $140. Think I can beat that? Should be good for 60a then right?
Will all that pull through 1" pvc? The #6 is listed as .249" and #8 as .213"
I know it will fit, I attached a diagram. I'm not sure about airspace requirements or anything like that. Any thoughts?

Also, does anyone know where to get a retaining clip for an old ITA load center?
My house main breaker is backfed (main lug panel), and as I understand it, a clip is required for code.
I'm green at AC electrical (not sure how to pull a breaker yet, do they just pull straight out?)

If a loadcenter was built before the retaining clip requirement, there will be no clips avail. BTW, never heard of a ITA, but ITE was a common make before Siemens dropped the name.
Edit:
If a backfed breaker was installed to the code in effect at the time the work was done, it does not have to be upgraded, the retainer clip was 1st required in 384-16(f) in the 1990 NEC.

 

[zmaxmotorsports]

How big is the service you will be feeding the shed off of from the house?

 

[alan_3301]

Thanks for the replies guys.

Yeah sorry it is ITE not ITA. I was thinking of getting a Siemens retainer clip to see if it would fit, but I don't see where it would go. If not necessary then I wont worry. If the inspector doesn't say anything, then I wont ask.

I said main lug panel earlier, but I guess there are no lugs. The busses go straight up past the first row breakers. Maybe the lugs would clamp on to the top of the buss. Shouldn't matter though, as I don't plan on touching any of that.

The panel is listed as 150a, but it has a 125a main breaker.
The service wire is 1/0 aluminum.

 

[Norcal]

If you can please post a picture of your panel.

 

[alan_3301]

Here you go.

 

[Norcal]

Someone removed the main lugs & backfed a breaker, & there may be a retainer clip, but it cannot be seen unless the adjacent breaker is removed, the clip fits between the 2 poles of the breaker at the backside where it plugs into the bus, the panel label does call for a "MBR-1" retainer clip.

 

[wyliesdiesels]

Here you go.

How many wires are there feeding that panel? Is there a disconnect at your meter socket or do the wires come straight from the meter?

 

[Deckape]

How many wires are there feeding that panel? Is there a disconnect at your meter socket or do the wires come straight from the meter?

It looks like the "Main" feed is the first double breaker on the right side (2 heavy black wires). I don't see any room to add anything else to this box as shown. He has 20 breaker positions including the feed. He'll need a sub-feed box off the mains to even have something tap into for power.

Alan, Did you think about solar or wind power? The right system could let you run the shop for free once it pays for itself.

 

[alan_3301]

How many wires are there feeding that panel? Is there a disconnect at your meter socket or do the wires come straight from the meter?

2 black wires and the bundle of neutrals.
The wires from the the meter come through the center lower knockout. No disconnect between the meter and the panel.

 

[alan_3301]

It looks like the "Main" feed is the first double breaker on the right side (2 heavy black wires). I don't see any room to add anything else to this box as shown. He has 20 breaker positions including the feed. He'll need a sub-feed box off the mains to even have something tap into for power.

Alan, Did you think about solar or wind power? The right system could let you run the shop for free once it pays for itself.

Yesterday I removed 4 15a breakers from the lower right, and added 2 tandem 15a breakers and a 2 pole 60a breaker in their place.

 

[alan_3301]

I picked up some 2-2-4-6 RHW-2 rated wire Individual red,black,white,green conductors. There is no sheath or jacket on the wires, just lightly twisted together. Is this a problem?
I understand it is ok for individual THWN wires inside a condiuit, but I guess the MHF is joined together in a cable by the insulation. Am I ok here?

 

[pattenp]

I picked up some 2-2-4-6 RHW-2 rated wire Individual red,black,white,green conductors. There is no sheath or jacket on the wires, just lightly twisted together. Is this a problem?
I understand it is ok for individual THWN wires inside a condiuit, but I guess the MHF is joined together in a cable by the insulation. Am I ok here?

Not sure how you plan to run it to say that you are okay. The individual wire twisted into a cable such as the Mobile Home feeder can be direct buried or run within conduit. Where the cable is exposed such as exiting the ground to enter the structure and also when inside of the structure the cable needs to be in conduit.

This is MHF so I assume what you got looks similar to this...

 

[alan_3301]

Ok it looks just like that, but with the colors I said earlier. I was under the impression MHF was 4 conductors inside a single insulation. Maybe I was thinking of URD. Or maybe I am not sure of any of this? I was thinking it would have a nylon jacket keeping all the wires held together.

I was going in 1.5" conduit from box to box, 16" underground. so everything will be protected.

Thanks, I should be ok, I just didnt want the inspector to look at it and ask where the jacket was, or "what is this stuff". I know if something loooks unfamiliar, they may be weary, even if specs are perfectly acceptable.

 

[pattenp]

You're thinking SER cable. SER has the outer jacket and is only for above ground and can be run the same as NM without conduit.

Check your depths, NEC is 18" deep to top of the conduit, so you need trench at 20".

 

[alan_3301]

Thanks for the heads up on the depth, not sure why I thought 16". Maybe I will just go full 24". I need the exercise anyways.

Thanks again for all your help!

 

[pattenp]

Just an FYI. For the aluminum wire use Noalox anti-oxidant compound on the wire ends at the connections.

 

[alan_3301]

I pulled the wire today, actually I pushed it through.
I ran a pull string and tied it to the wire, but it slid right through with no problem.
Took about 20 minutes by myself to push the 2-2-4-6 through 60' of 1 1/2 sch 40 conduit. It has 2 90 degree bends and a 45 degree bend.
Just posting in case anyone searches. I was worried it'd be a pain, but it was easy!