Needing Electrical Help

[whadeezlrg]

So here's my situation:

-I have a detached shed/garage on my property that I'm considering running a few(3) 1000w gavitas(4.8a @ 240v ea) and a 2 ton mini split(9.8a @ 240v) plus one auxillary 15a 120v circut that will just be running a few wall fans and maybe an inline fan, I'm assuming it wouldn't be running more than 3-5a @120v at any given time so this bring me to a total of 30.2a max at any given time. it is approximately 60-80ft away from the panel, which is about 15-20ft farther from the shed than the existing dryer circut in my attached garage(if the load is just too much I'm all for running a separate 120v 15a to run the aux. components)

-I rent this place and would like to keep things somewhat temporary, mainly meaning my plan is to tie/plug into an existing 30a 240v dryer plug that for whatever reason the previous residents have wired to a 40a 240v breaker(not sure if the wire is 10 or 8 gauge, probably should check because having a 40a supply would give me the 20% cushion on the breaker capacity vs load...would just need to upgrade the receptacle to be rated for 40 as well) I use a gas dryer, the circuit does not get used at all.

-so my plan is this: put a male dryer plug end onto some 8-2 stranded outdoor cable(it's an older house the dryer circuit is hot-hot-ground) bury the cable for the run to my shed(pvc conduit is also another option but im trying to think along the lines of safe temporary) and land the wires into a sub panel in the shed and branch off the circuits I will need from there. If I am only running 2 hots and a ground/neutral from existing circuit to the sub panel will i need to drive a copper grounding rod and tie the sub panel into that and keep the grounded bus bar separate from the ground/neutral that I'm pulling from the existing circut?

- I have taken a couple of classes at the community college for electrical, and have worked for a company doing mainly commercial/retail remodeling with about 30-50% of my workload revolving around basic electrical...my point is I'm somewhat electrically competent, and can make safe connections and understand the basic principles of electricity, but definitely have more to learn.

- I wouldn't be opposed to running 4 lights on a 2-2 flip-flop either, in order to free up more load capacity on the circut

any advice on the subject is greatly appreciated

 

[whadeezlrg]

so rives, where ya at bud?

what about just running some direct burial uf-b 6/3 from the panel on a 50amp breaker and installing a sub-panel? would I be ok doing that @ 100ft without too much voltage drop? would I need to drive some copper ground rod(s) in at the shop and tie my ground block on the sub-panel into it as well as the grounded wire running from the load center? does the neutral block need to be insulated on the sub panel so it's not crossing with the ground?(I think I know that neither are technically carrying current but I just want to know if they need to be isolated all the way back to the load center)

 

[Swollencalyx]

Whadeezrig
So I would run the 6/3 like you said with a 50amp main breaker at each panel just cause I'm over kill for safety. If you're running a "sub-panel" do not run ground rods. You're creating a separate system for the shed. So the ground and the neutral should not be tied together. Green wires to one side. White to the other. They tie back together at your main panel and then go to "earth" ground at your main panel. Hope that helps, licensed journeyman with a passion for the plant. Cheers.

 

[whadeezlrg]

so in order to put a "main breaker" in at the sub panel I'm assuming i just land the hots from the main panel into a 240v single throw 50amp breaker and just bypass the feeder lugs at the top of the sub panel?

 

[Swollencalyx]

so in order to put a "main breaker" in at the sub panel I'm assuming i just land the hots from the main panel into a 240v single throw 50amp breaker and just bypass the feeder lugs at the top of the sub panel?

Yes that is correct. That is called back feeding the panel.

 

[whadeezlrg]

thank you sir!

 

[rives]

Whadeezrig
So I would run the 6/3 like you said with a 50amp main breaker at each panel just cause I'm over kill for safety. If you're running a "sub-panel" do not run ground rods. You're creating a separate system for the shed. So the ground and the neutral should not be tied together. Green wires to one side. White to the other. They tie back together at your main panel and then go to "earth" ground at your main panel. Hope that helps, licensed journeyman with a passion for the plant. Cheers.

Sorry, but the highlighted information is incorrect. Per NEC article 250.32 (A), if the sub-panel is in a separate structure, then a ground rod is required for the sub.

Also, if you are going to backfeed the sub through a breaker as described up above, the breaker is supposed to be mechanically fastened in place so that you don't wind up juggling a hot breaker if you bump it loose from the busses.

 

[whadeezlrg]

Sorry, but the highlighted information is incorrect. Per NEC article 250.32 (A), if the sub-panel is in a separate structure, then a ground rod is required for the sub.

I thought that I had read the same thing somewhere thus my emphasis on that point, thanks for the clarification

Also, if you are going to backfeed the sub through a breaker as described up above, the breaker is supposed to be mechanically fastened in place so that you don't wind up juggling a hot breaker if you bump it loose from the busses.

Any particular method you would recommend to accomplish this? Obviously screwing through/into a breaker would have to be a bad idea? I would think the options for attachment would be pretty limited in such a critical space.

Thanks, for your input!

 

[rives]

Some panel manufacturers make a screw clip for exactly that purpose. The attached link is for a Square D version, but they are pretty common. What brand load center are you using?

http://static.schneider-electric.us...rs/Accessories-QO-LK-PK-QO-QON/1100HO9902.pdf

 

[whadeezlrg]

I haven't made the purchase yet. In the past I have used square d just because it's the common thing @ the depot, and will likely be going that route this time around as well.
Thanks for your help, much appreciated

 

[rives]

Happy to be of some help!

Talk to the people at HD about what you need - they probably stock them for their panels. A main breaker conversion kit would also do it, but would probably be more costly.

Just for information, my preference is normally for GE - I've found their breakers to be very reliable over the years and the busses are copper where other manufacturers frequently uses aluminum.

 

[Swollencalyx]

Sorry, but the highlighted information is incorrect. Per NEC article 250.32 (A), if the sub-panel is in a separate structure, then a ground rod is required for the sub.

Also, if you are going to backfeed the sub through a breaker as described up above, the breaker is supposed to be mechanically fastened in place so that you don't wind up juggling a hot breaker if you bump it loose from the busses.

Ok you busted me, I should of read the post more clearly. Separate building was key. My bad. Good catch.
Cheers.

 

[whadeezlrg]

ok well here's a little update:

I ended up purchasing a shipping container to build out instead of building my detached shop up. I'm still planning on the same basic setup although I plan on running a total of 4 1000w gavitas @ a total draw of 19.2a@240v + a 2 ton mini split 9.8a@240v with an auxiliary circuit that may draw up to 10a@120v which puts me right under 40amps max load.

I'm planning on running 6/3 UF wire from the panel into the houses' raceway into the attic and across the house, down through the inside of one of the exterior walls and out from near the bottom of the wall into a pvc conduit that drops into the ground about 18" deep from there it as about an 8ft run underground half of which is convieniently located under the container(thinking I'll go direct burial for this stretch), then up through the floor of the container through some more pvc conduit and finally landing in the sub-panel mounted on a wall built inside of the container. I plan on putting 50a breakers on either side of the run.

any advice on pulling that cable into the raceway? I've only ever done commercial work where this stuff is a lot more accessible but getting that cable ran through the raceway directly into the attic is a big deal in order to keep all of this work well hidden

will I be fine running the 6/3 @ a distance of around 100ft total without too much voltage drop?

and I know you were more than clear on this but: will I still need a grounding rod even if I'm running an isolated circuit from the main panel using 6/3? or should I just go with 6/2 and tie in my ground at the container?

the raceway issue is the biggest road block for me at this point, I really don't want to run from the panel into my garage through conduit into my attic as not only is it fairly obvious that there is some kind of electrical work running through it but it would also require more than 360* of total bends thus requiring me to put in extra junction boxes etc...keeping all of this work out of sight is a top priority under safety obviously. fwiw my garage looks more like a finished living room than a typical garage, it's got an open vaulted ceiling, finished sheetrock, painted etc...conduit will stick out like a sore thumb

 

[rives]

How are you planning on making the transition from PVC to direct burial? I think that I would probably keep it all in PVC just to avoid needing to bed the wire and in case you ever wanted to pull it back out. You aren't going to save more than a couple of bucks on the pipe, and it keeps more options open in the future.

What kind of "raceway" are you referring to? Is this just a stud-wall opening, is there some form of metal raceway like a gutter, or what? Usually when you pull wire into conduit, you use a special lubricant that won't damage the insulation over time. If your conduit run can be extended from panel-to-panel, you could use individual conductors rather than a UF cable, and it would be easier to pull - having the conductors all in one jacket like that makes it difficult to go around corners where some strands need to get longer, and the ones on the inside of the bend get shorter as you go around the bends. If you need to break the run up because of physical constraints and have to stay with the UF cable as a result, be sure and oversize the conduit by a fair margin - it's cheap, and it will be a lot easier.

#6 wire is rated for 60+ amps with most types of insulations. The voltage drop for a 60a load, 240v, for a 100' run is under 2.5%, so you are in good shape. You are allowed 5% on residential installations, but it is best to stay with the industrial requirement of staying under 3%. Any HIDs will be a lot happier and will see fewer restarts from voltage sags.

Yes, you have to have a ground rod with a separate structure. You are getting your terms tangled up a bit - you would only use 6/2 if you wanted a 240v-only service, and you would still need 6/2 w/ground. You will need 6/3 w/ground for what you are doing so that you will have a neutral, (2) hot wires, and a ground. They make the cables both with and without the ground wire, so you need to keep your terms straight.

 

[whadeezlrg]

How are you planning on making the transition from PVC to direct burial? I think that I would probably keep it all in PVC just to avoid needing to bed the wire and in case you ever wanted to pull it back out. You aren't going to save more than a couple of bucks on the pipe, and it keeps more options open in the future.

I was under the impression that it's frowned upon to run sheathed cable through conduit for over a certain length that I believe was less than the 16' or so that I would need outside of the exterior wall...I honestly didn't have a 'plan' on how I would terminate the conduit. Conduit for that stretch seems much more logical for sure, but since I'd like to run the cable down from the attic through the inside of the wall and be able to 'hide' the conduit that's exiting the stucco wall by having it exit fairly close to ground level...or I just say screw it and run romex thru the attic and catch a junction box and run conduit from the attic out of the wall and run some THHN through the conduit, that would surely be the easiest way to run it...what do you recommend for splicing #6 wire?

What kind of "raceway" are you referring to? Is this just a stud-wall opening, is there some form of metal raceway like a gutter, or what? Usually when you pull wire into conduit, you use a special lubricant that won't damage the insulation over time. If your conduit run can be extended from panel-to-panel, you could use individual conductors rather than a UF cable, and it would be easier to pull - having the conductors all in one jacket like that makes it difficult to go around corners where some strands need to get longer, and the ones on the inside of the bend get shorter as you go around the bends. If you need to break the run up because of physical constraints and have to stay with the UF cable as a result, be sure and oversize the conduit by a fair margin - it's cheap, and it will be a lot easier.

All of the wiring for the house goes directly up and out of the panel into a drywall/plywood 'box' that runs the length of the garage towards and into the attic, from that point the cable's all go to their destinations, I'm assuming that raceway is probably the wrong term...I used steel raceways on the retail jobs that just dropped wire from the T-bars down to cash registers etc.

I'd like to run this cable through the same channel if possible? I honestly don't know if it's only accessible during initial construction of the house or what

#6 wire is rated for 60+ amps with most types of insulations. The voltage drop for a 60a load, 240v, for a 100' run is under 2.5%, so you are in good shape. You are allowed 5% on residential installations, but it is best to stay with the industrial requirement of staying under 3%. Any HIDs will be a lot happier and will see fewer restarts from voltage sags.

Awesome

Yes, you have to have a ground rod with a separate structure. You are getting your terms tangled up a bit - you would only use 6/2 if you wanted a 240v-only service, and you would still need 6/2 w/ground. You will need 6/3 w/ground for what you are doing so that you will have a neutral, (2) hot wires, and a ground. They make the cables both with and without the ground wire, so you need to keep your terms straight.


Ok, I knew that was going to be the answer, I was honestly just thinking that since I'd be adding a grounding rod that it was possible that I would only need to carry 2 hots and a neutral from the main and I'd pick up the ground from the rod, thus requiring 6/2(which wouldn't have worked anyways since the bare wire is a #10 bare copper, so oops!)...if that makes sense? gonna go ahead and go with the 6/3 and a grounding rod!

do you happen to know how deep the ground rod needs to be driven?

Also, does the neutral bus bar need to be insulated from the sub panel or just isolated meaning that ONLY neutral wires can be connected to it? I'm assuming that any screw's that mount it to the panel would deem any insulation useless?

Anyways, Thank you so much man! I really appreciate it! you should get paid for all of the advice you give out on the subject! I'd like to buy you a beer or something one of these days!

I'm probably going to have more questions as this progresses as well, so thanks in advance! I'll try to keep my terms straight next time

 

[rives]

8' copper-clad ground rods are standard, usually there is a foot or so left exposed.

It is both insulated and isolated, meaning that it is mounted on non-conductive standoffs and the only wires that get landed on it are the neutral wires. Panels that are used for a main either have a bonding jumper that ties the neutral buss to the can, or there is a long screw (typically anodized green) that will insert through the buss all the way into the back panel.

Holler anytime. If I happen to miss your post update for some reason, drop me a PM.

 

[Swollencalyx]

do you happen to know how deep the ground rod needs to be driven

Also, does the neutral bus bar need to be insulated from the sub panel or just isolated meaning that ONLY neutral wires can be connected to it? I'm assuming that any screw's that mount it to the panel would deem any insulation useless?

Anyways, Thank you so much man! I really appreciate it! you should get paid for all of the advice you give out on the subject! I'd like to buy you a beer or something one of these days!

I'm probably going to have more questions as this progresses as well, so thanks in advance! I'll try to keep my terms straight next time[/QUOTE]

Ground rods come in 8ft lengths. Use 2 of them with #6 bare copper between them in one continuous cut. And yes the green bonding screw will be used. So that the neutral and the ground are tired together.
Sounds like you are headed in the right direction. Stay safe

SC

 

[rives]

And yes the green bonding screw will be used. So that the neutral and the ground are tired together.
Sounds like you are headed in the right direction. Stay safe

SC

No, the bonding screw is not used. It is a sub-panel, not a main, and should be done per the drawing in post #14. The only place that the neutral and ground are bonded together is at the main.

 

[whadeezlrg]

hey rives, not sure if you noticed but I asked some other questions in my last reply to your post in Blue. getting close to getting started on this, probably within the next week or so. thanks again.

 

[rives]

Hell, I completely missed it - I just thought that it was the quote from above!

I don't recall ever seeing an exclusion on putting a sheathed cable into conduit. Multi-conductor sheathed cable is frequently used in industrial work, but it is stranded wire and would lend itself to pulling much more easily. Split-bolts, lugs or barrel connectors are normally used for splicing larger wire. If you have big crimpers, then crimp-on lugs or barrel connectors would probably be the fastest, but split-bolts are very common. Make sure that you get plenty of tape on any of them - as the wire heats up under load, it is pretty easy for a sharp spot in the connection to eventually squirt it's way through the tape and then ground out, particularly if the spliced area is pushing against a sidewall of the junction box. I normally use varnished cambric directly over the joint and then use Scotch 33 or 88 over the top of that, but cambric would be hard to source outside of an industrial supply house and it's expensive as hell.

I wouldn't want to run unjacketed wire through a wooden raceway.... Can you run some flex through that portion? A raceway doesn't need to be accessible in the future, but any splices have to be kept accessible.

Make sure that you spec 6/3 w/ ground.