electrician (tech inside) question

[trampas]

Okay i purchased the 285'/3 #6 wire for my shop run. Just gotta trench the conduit in now, and terminate. I still haven't bought the conduit but i'm thinking a little bit larger than 1" should be great.

My question is, when i do the pull from the sub, w/ approx a 50a dual-breaker... i need to run it to another sub powering up the original grandfathered shop, and the new shop sub also. How would i either 'continue the run' or split it at the second shop subpanel? I'm not pulling permits on this particular stage of the build, because power and panels are already present.. i'm just upgrading and i plan on pulling permits once this leg of the job is complete.

thx! :beer:

[toymoto]

I think I was talkin to ya about this a while back. There are a couple of different ways to branch off to the second shop.

I would recommend putting a pvc junction box in the ground at a convienient place to split the line. You can used split bolt connectors and rubber tape to insulate the connections or just buy connector blocks. We sell Polaris black connectors (http://www.nsipolaris.com/) and they make it pretty easy.

[trampas]

Sounds great - it's okay to do a J-box underground?

[ImNotRight]

I'd probably try to do it where it's accessible..IE above ground.

[toymoto]

AFAIK it's fine in Texas, don't know about Cali. On second thought it may be easier to stub it up and mount the J-box to the exterior of the first shop. It would help kept some of the moisture out.

Like this :D

http://www.texasoffroad.net/albums/lonestar/album301/box.jpg

[steveh]

That's a real bad idea, splitting the line.

How far from the main are these subs? 285' of #6 ??? 50 amps?? BTW, if you do plan on going 285', your only good for 25amps safely

The calculator below recommends #3

go here and get in the ball park
http://www.elec-toolbox.com/calculators/voltdrop.htm

Can't tell ya how to put in 2 subs without more info.

2 ways I would do it:

1) Run both subs separately from the main
2) Daisy chain the subs, IE, run a sub off the main, and another sub of the sub. But you damn well better have the wire sized right!

Also, if it was my shop, i'd want at least a feed capable of 100amps minimum

[toymoto]

IIRC there was not much load on the shops(lights etc.) If you run the sub off of the sub you would be forcing the load through the middle box. That just doesn't sound right. I don't think running a second line is an option since he has already purchased the wire also he would have to go with a 2" conduit just to fit them both in there. Cost of the project would probably triple...

[toymoto]

GEEZ! :eek:

I just did the little calculator thing and it recommends #3, Whatever that guy set that thing on is way off base...ambient temp., wire type, or open/buried cable. It's off somewhere.

[steveh]

Like I said, without the details, it's all speculation. My concern for him is that he purchesed to small of wire if he is expectiong to provide 50amps 285' from the main.

LP, post some details if you want better info

[steveh]

GEEZ! :eek:

I just did the little calculator thing and it recommends #3, Whatever that guy set that thing on is way off base...ambient temp., wire type, or open/buried cable. It's off somewhere.

Are you an electrician? That calc is right!

[trampas]

Nice drawing toymoto. :)

Steve.. i over-bought on the length for other reasons. The main is approx 145' away from sub no. 1 at the first shop. Additional run to no. 2 shop is approx 40'.

I don't mind splitting before the first of the 2 subs, i don't plan on running a business out of either, nor do i plan on running any 220v appliances of any type right away. Possibly a 220v comp but i could run it when no other high-current apps are being run/drawn.. and i don't have such comp yet anyway.

I can understand the 'desire' for 100a - or for that matter, the 'need'. :D Since i'm the one and only person utilizing both shops, only singular draw would be in place from the split. Oh, and having the job-cost triple is not in the cards. ;)

[steveh]

Nice drawing toymoto. :)

Steve.. i over-bought on the length for other reasons. The main is approx 145' away from sub no. 1 at the first shop. Additional run to no. 2 shop is approx 40'.

I don't mind splitting before the first of the 2 subs, i don't plan on running a business out of either, nor do i plan on running any 220v appliances of any type right away. Possibly a 220v comp but i could run it when no other high-current apps are being run/drawn.. and i don't have such comp yet anyway.

I can understand the 'desire' for 100a - or for that matter, the 'need'. :D Since i'm the one and only person utilizing both shops, only singular draw would be in place from the split. Oh, and having the job-cost triple is not in the cards. ;)

Ok, that helps knowing the first run is 145'. #6 is fine at 50amps fo sho. Defintly make it 220, so it's ther if you need it down the road.

So, what do you wnat the other location to have amps wise?

[rusted]

Run the sub-sub configuration. That way all the terminations are up to par and all feeders are protected by overcurret devices.

Remember not to bond the subpanels.

You are going to run a voltage drop with that cable. Voltage drop is NOT a safety issue, it's simply inefficient.

You will have a 6% voltage drop at 50 amps and 240 volts. The drop will be 14.54v, leaving you ~225v.

However, you would be better off running a 1/0 and 100amps, and use the 50amp breaker in the new subpanel for the grandfathered subpanel, and run the #6 to that. Simply a reccommendation.

In any case, avoid a spliced or junctioned feeder.

*edited for bad math.

[steveh]

Run the sub-sub configuration. That way all the terminations are up to par and all feeders are protected by overcurret devices.

Remember not to bond the subpanels.

You are going to run a voltage drop with that cable. Voltage drop is NOT a safety issue, it's simply inefficient.

You will have a 3% voltage drop at 50 amps and 240 volts. The drop will be 7.26v, leaving you ~233v.

However, you would be better off running a 1/0 and 100amps, and use the 50amp breaker in the new subpanel for the grandfathered subpanel, and run the #6 to that. Simply a reccommendation.

In any case, avoid a spliced or junctioned feeder.

Yep, I could not agree more. I just put this one in, with #1, for a second HVAC system and upcoming kitchen remodel: The 2 condiuts going up are empty, so I can fish the Kitchen wiring easily via the attic access

[trampas]

Run the sub-sub configuration. That way all the terminations are up to par and all feeders are protected by overcurret devices.

Remember not to bond the subpanels.

You are going to run a voltage drop with that cable. Voltage drop is NOT a safety issue, it's simply inefficient.

You will have a 3% voltage drop at 50 amps and 240 volts. The drop will be 7.26v, leaving you ~233v.

However, you would be better off running a 1/0 and 100amps, and use the 50amp breaker in the new subpanel for the grandfathered subpanel, and run the #6 to that. Simply a reccommendation.

In any case, avoid a spliced or junctioned feeder.

Steve.. i only want the new shop to have woodworking current draw - tablesaw / radial arm saw / beamsaw / chopsaw / 110v 5h comp / and lighting.

Rob - i'm not going 1/0 so forget it. :D

Now for the rusted questions; ;)

I understand having even more protection by using the sub-sub configuration - however - like installing a multi-outlet 110 box where you never do this, isn't it daisying the draw say if i were to have lights and the like on in shop no. 1?

Bonding the sub's - i don't know what that is.

Voltage drop i can live with. Inefficiency is alright also. I'll procure methodologies to reduce those factors' impacts.

Why avoid a junctioned feeder... why?

[rusted]

Yep, I could not agree more. I just put this one in, with #1, for a second HVAC system and upcoming kitchen remodel: The 2 condiuts going up are empty, so I can fish the Kitchen wiring easily via the attic access

That is good work. Sorry about my calc, I did it one-way the first time, of course.

My new main panel will be a sub from an outside meter base with breakers. I am running my 100amp 1/0 SE shop cable directly from the meter base. Makes for very easy upgrades when I do the outside shop as well.

I am replacing a 6/2 for the HVAC with the 1/0, and running a 6/2 50 for the welder and a 30 6/2 for the HVAC.

I've been a busy busy boy.

Those empty conduits are smart, and you could even drop fish string if you wanted to, but with the box being lower that's not really an issue.

[steveh]

LP, what was you plan for running the wires? Rusted is saying to make sure each leg is protected by an approriatly rated breaker, or you risk burning the shops down .....

[steveh]

That is good work. Sorry about my calc, I did it one-way the first time, of course.

My new main panel will be a sub from an outside meter base with breakers. I am running my 100amp 1/0 SE shop cable directly from the meter base. Makes for very easy upgrades when I do the outside shop as well.

I am replacing a 6/2 for the HVAC with the 1/0, and running a 6/2 50 for the welder and a 30 6/2 for the HVAC.

I've been a busy busy boy.

Those empty conduits are smart, and you could even drop fish string if you wanted to, but with the box being lower that's not really an issue.

LOL! So i'm not the only one who wrenches on th house more than the toys at times .......

I used 2" sch 40 from the main into a 6x6x4 Jbox in the garage. Then went 1.5" sch 40 the rest of the way to the sub. That way if I need to add another run into the garge for a 220 I can.

At some point I will build a large shop, and may just have a new service brought in for it.

[rusted]

Steve.. i only want the new shop to have woodworking current draw - tablesaw / radial arm saw / beamsaw / chopsaw / 110v 5h comp / and lighting.

Rob - i'm not going 1/0 so forget it. :D

Now for the rusted questions; ;)

I understand having even more protection by using the sub-sub configuration - however - like installing a multi-outlet 110 box where you never do this, isn't it daisying the draw say if i were to have lights and the like on in shop no. 1?

Bonding the sub's - i don't know what that is.

Voltage drop i can live with. Inefficiency is alright also. I'll procure methodologies to reduce those factors' impacts.

Why avoid a junctioned feeder... why?

With a feeder running from panel to panel, you can take advantage of ground terminations. For a junction in a ground conductor, the NEC specifies permanent lugs or exothermic welding for certain conductor sizes. Don't even get into that territory. The sub-panel functions as an excellent junction box. The terminals have torque-ratings to make sure of proper bonding mechanical integrity.

For your primary service panel, your nuetral and ground are bonded in that panel. Once you run an overcurrent-protected feeder from that panel, all subsequent panels have SEPERATE ground and nuetral buses. You cannot mount white wires to the ground bus, and cannot mount the equipment ground to the nuetral bus.

All modern panels that can function as a sub-panel have something called a 'bonding screw' If you are buying brand new, this screw is clearly marked. When you are running a subpanel, DO NOT install the bonding screw, and keep your equipment ground and neutral buses seperate as mentioned above.

As you can see, in this situation you benefit from a sub-sub configuration due to proper, SAFE grounding, the creation of a reliable nuetral path, especially for your shop which will run all sorts of motors.

Ok, skip the 1/0, DON'T skip the feeder/subpanel configuration. :D

[trampas]

LP, what was you plan for running the wires? Rusted is saying to make sure each leg is protected by an approriatly rated breaker, or you risk burning the shops down .....


Alright you're confusing me a little (not that hard, given the circumstances :flipoff2: )

I'm pulling 3/6 through 1-1/4" underground pvc conduit - from that point - is what this thread is about - i wanted suggestions from there to power BOTH subs - one sub is already in place - i'm in the shop now looking at the subpanel behind my monitor. :D

[steveh]

I now pass the podium to rusted, who is much better at 'splaining all of this than I am ...

[rusted]

Man I had the whole post typed and my son messed with the mouse. :rolleyes:

Ok, LP, open up the box and let's look inside. Take a look at this box:

Yellow: This is where the entrance cable ground conductor will go.

Green: This is where the branch circuit grounding conductors go. This would include another feeder, liek the one to your grandfathered shop. This is what bonds ground back to your main panel, bonds the panel to ground, and keeps a seperate path from nuetral.

Red: Nuetral bus. This is where all white wires go. No ground wires go here.

Blue: Bonding screw location. Notice, no screw installed. The nuetral is NOT electrically connected to the panel (ground). All the subpanels are wired this way. This is an older QO 100amp panel. Post pics of your guts and let's see.

[trampas]

With a feeder running from panel to panel, you can take advantage of ground terminations. For a junction in a ground conductor, the NEC specifies permanent lugs or exothermic welding for certain conductor sizes. Don't even get into that territory. The sub-panel functions as an excellent junction box. The terminals have torque-ratings to make sure of proper bonding mechanical integrity.

For your primary service panel, your nuetral and ground are bonded in that panel. Once you run an overcurrent-protected feeder from that panel, all subsequent panels have SEPERATE ground and nuetral buses. You cannot mount white wires to the ground bus, and cannot mount the equipment ground to the nuetral bus.

All modern panels that can function as a sub-panel have something called a 'bonding screw' If you are buying brand new, this screw is clearly marked. When you are running a subpanel, DO NOT install the bonding screw, and keep your equipment ground and neutral buses seperate as mentioned above.

As you can see, in this situation you benefit from a sub-sub configuration due to proper, SAFE grounding, the creation of a reliable nuetral path, especially for your shop which will run all sorts of motors.

Ok, skip the 1/0, DON'T skip the feeder/subpanel configuration. :D

Steve, you've both (hell, all of you) been most helpful.

Rob i intended originally to run the sub-sub configg... only toymoto's post got me thinking otherwise.

How do i run an overcurrent-protected feeder from the 1st to the 2nd sub? - i think i need to do some reading :rasta:

[steveh]

LP, the breaker is the over current protection. So, you would add a breaker to the sub with wire feeding the next sub.

And LP, kill the power to the panel before you open it up ... unless of course you are a certified sparky .....

[rusted]

Steve, you've both (hell, all of you) been most helpful.



How do i run an overcurrent-protected feeder from the 1st to the 2nd sub? - i think i need to do some reading :rasta:

The feeder is wired just like a branch circuit. You are allowed in some instances to forgoe overcurrent protection, just forget it in your case, it's dangerous anyway.

So you install a 50amp breaker in your main panel, and that goes to your sub.

The sub then has the ground NOT bonded. And you wire another 50amp branch for your sub panel, which again is wired the same way.

Just remember, no panel BUT the main panel is bonded.\

As you can see, every wire, even the feeders, have their overcurrent protection. This opens up how you can wire them, therefore less rules to memorize.

Also, the ground bonding as you can see accomplishes this: Only at the main panel are nuetral and ground bonded. If you have an electric motor that makes nuetral hot, you could run hot grounded cases on say a drill. But the main house ground is also at the panel, and that will ground anything in your home.

But, as subsequent panels, you have to rely on the feeder cable for a ground. That ground could easily fail, and a hot-nuetral feedback will lead to all your tools being 110v shock devices.

That's just a little theory behind the rules.

[steveh]

I found this jpg, does this help you visulize?

http://danswiringpage.com/diagrams/subpanel.jpg

[rusted]

I found this jpg, does this help you visulize?



There ya go, that makes sense of my garbled crap. :D

[trampas]

So you install a 50amp breaker in your main panel, and that goes to your sub.

done

The sub then has the ground NOT bonded. And you wire another 50amp branch for your sub panel, which again is wired the same way.

see pics

Just remember, no panel BUT the main panel is bonded.

will reinstall new 1st sub if necessary, sounds like it is.

As you can see, every wire, even the feeders, have their overcurrent protection. This opens up how you can wire them.

?


But, as subsequent panels, you have to rely on the feeder cable for a ground. That ground could easily fail, and a hot-nuetral feedback will lead to all your tools being 110v shock devices.

so how do i accompplish this

[trampas]

I found this jpg, does this help you visulize?



Yes! I think i need to install a different 1st sub. This is all becoming clear now, thanks.

[steveh]

I picked up my GE Sub at Lowes. I choose it becuse GE makes 1/2" wide single pole and 1" wide double pole breakers. So they take up half the space.

[seajeeper]

The only reason to run the second subpanel from the 1st sub panel would be the convenience of being able to shut off the power to the second shop w/o shutting it off to the first shop.

It seems that running it from the 1st sub panel only looses you 2 breaker spaces, what does it gain you? (Other than that stated previously)

[Gummi Bear]

OK,

If you're confused, you should be, this can be pretty confusing.

For your feed from shop 1 to shop 2, you'll need to add an additional breaker to the panel (which appears to be full, so it's now time for a bigger panel, with more breaker spaces) Assuming you had the breaker space, you would add a 2 pole 50A breaker (Square D part # QO250) to the panel, and land your two conductors to the breaker (black, red) and the white would land on the neutral bar (isolated from the panel) (grounded conductor) the green (#10 is sufficient) would land on the ground bar.

The decision to feed from the main panel or the sub panel is yours, either way, on a 50A breaker, you will have sufficient overcurrent protection. Just make sure that your conductors and conduit are sized accordingly. I'd look into oversizing the conductors, copper price is finally on the decline, after a 6 month climb earlier this year.

Modern breakers are a thermal magnetic trip, meaning that they will trip, or turn themselves off, if they get too hot, or there is another severe interruption of the current. Having one breaker after another is not necessary, but some folks do insist that it is a good idea. My one big thing, when I design a new building, is that I like to put a main breaker in each panelboard or switchboard if the source is not readily available, for the ability to shut down the panel, without having to run all over creation to do so. Not always necessary, but I am a stickler for safety and ease of maintenance.

For conduit, I'm a big fan of easy, so I oversize all of my conduit. You can have as much as a 40% fill legally (looking at a cross section of the conduit and conductors, the conductors may only fill 40% of the interior of the pipe) For a 3 #6, 1 #10 run, I'd go with 1-1/4" (for the easy to pull factor). With PVC still being cheap, I'd even step it up to 1-1/2 or even 2" just for the future upgrade factor already built in.

150' isn't too bad of a pull, if you plan properly. Have someone show you how to make up a pulling head, and get yourself some pulling lubricant *called pulling soap* You can use a fish tape for a pull with wires that small, but a rope would be easier to pull (1/4" braided rope, with an eye splice at the feed end to make wires up to) I've used everything except an ox to pull wire, if you are gentle, you can use a tractor, 4 wheeler, or even a pickup to do the hard pulling (make damn good and sure that your pipes are strapped securely and the panel is mounted securely if you plan to use any sort of machinery to pull the conductors)


Steve - add a couple of straps to those conduits, other than that, your installation looks pretty decent.

Rusted - you've been studying pretty hard, and are getting a good grasp of the NEC, but my advice to strap on some tools and work in the field still stands. Good luck with your studies.

LasPalmas - if you are still confused, or need any more help, feel free to PM or email me. I'll do what I can to make it a little bit more clear. Steve and Rusted have done a pretty decent job so far though.

[trampas]

For your feed from shop 1 to shop 2, you'll need to add an additional breaker to the panel (which appears to be full, so it's now time for a bigger panel, with more breaker spaces) Assuming you had the breaker space, you would add a 2 pole 50A breaker (Square D part # QO250) to the panel, and land your two conductors to the breaker (black, red) and the white would land on the neutral bar (isolated from the panel) (grounded conductor) the green (#10 is sufficient) would land on the ground bar.

The decision to feed from the main panel or the sub panel is yours, either way, on a 50A breaker, you will have sufficient overcurrent protection. Just make sure that your conductors and conduit are sized accordingly. I'd look into oversizing the conductors, copper price is finally on the decline, after a 6 month climb earlier this year.

Modern breakers are a thermal magnetic trip, meaning that they will trip, or turn themselves off, if they get too hot, or there is another severe interruption of the current. Having one breaker after another is not necessary, but some folks do insist that it is a good idea. My one big thing, when I design a new building, is that I like to put a main breaker in each panelboard or switchboard if the source is not readily available, for the ability to shut down the panel, without having to run all over creation to do so. Not always necessary, but I am a stickler for safety and ease of maintenance.

For conduit, I'm a big fan of easy, so I oversize all of my conduit. You can have as much as a 40% fill legally (looking at a cross section of the conduit and conductors, the conductors may only fill 40% of the interior of the pipe) For a 3 #6, 1 #10 run, I'd go with 1-1/4" (for the easy to pull factor). With PVC still being cheap, I'd even step it up to 1-1/2 or even 2" just for the future upgrade factor already built in.

150' isn't too bad of a pull, if you plan properly. Have someone show you how to make up a pulling head, and get yourself some pulling lubricant *called pulling soap* You can use a fish tape for a pull with wires that small, but a rope would be easier to pull (1/4" braided rope, with an eye splice at the feed end to make wires up to) I've used everything except an ox to pull wire, if you are gentle, you can use a tractor, 4 wheeler, or even a pickup to do the hard pulling (make damn good and sure that your pipes are strapped securely and the panel is mounted securely if you plan to use any sort of machinery to pull the conductors)



Thanks Gummi Bear, you've spelled it out very nice.

I'd like to use the existing panel if possible, and as you can see near to the right is a pair of 20a breakers, (pinned with a finish nail) that are not in use actually. So theoretically i could install a 50a to the next sub there, correct?

Thanks for the info on wire and conduit also. I think i'll go 1-1/2" now that you've shared the legal-fill capacity to me.

[steveh]

Thanks Gummi Bear, you've spelled it out very nice.

I'd like to use the existing panel if possible, and as you can see near to the right is a pair of 20a breakers, (pinned with a finish nail) that are not in use actually. So theoretically i could install a 50a to the next sub there, correct?

Yes, if, the wire feeding from the main to the sub, and from sub 1 to sub 2, is also sized to handle 50amps over the entire length of both runs.

Why is this important? Because if the wire is not up handling 50 amps, it will act as a fuse and melt, likley catching on fire.

[toymoto]

Are you an electrician? That calc is right!


I do sales for an electrical distributor(7 years,mainly Cutler-Hammer and GE) I answer questions like this all day long and apprentice to my father, a master electrician. Also you are right about the calc...kind of. :flipoff2:

Based on a certain set of parameters that is correct but can change drastically by looking at a few key points. The first being the temperature rating of the wire; if he bought the trey cable (vntc) I recommended then it uses THHN (90*C)for the conductors. Which is a 15 ampere difference between UF (60*C)cable.

The second is how the cable is being run. Copper THHN in free air is rated much is rated at a much higher ampacity than in a raceway, cable, etc. #6 in free air is rated 105amps compared to 75amps in a cable, due to the wire being able to dissipate heat in free air.

Looking at the calculator I would say it could skewed by the temp of the wire, probably using UF or TW type wire. But as you see there are factors that change the ratings. The Rule of thumb (http://www.pirate4x4.com/forum/showthread.php?t=253998&highlight=rule+thumb) that we always use is to up the wire size one time for every 100' over the first 100' up to about 400'. Over that you would probably need a Buck/Boost transformer.

Those thin GE breakers will (normally)only fit in the lower portion of the box, it keeps the installer from over loading the panel with too many circuits so be careful.

This seems to have gotten very technical for a fairly simple install BUT you can never be to careful when it comes to your home. There are normally so many unknown factors in answering such questions many times I am forced to generalize the answers. I would suggest buying an Ugly's Reference book, it is very handy for sizing wire, conduit, calculations and so on. :)

[rusted]

Well, that looks like a QO, right?

The green is the bonding location. Your bonding screw is not installed.

However, the red arrow looks like a #4 ground conductor to me, hooked directly to the nuetral bus. Also, it appears that you have both neutral and equipment ground conductors to the neutral bus.

I would make sure that the incoming ground, AND the equipment grounds go to a seperate bus bar mounted directly to the box, like mine in the photo I drew all the arrows on. Just make sure your neutral and grounds are electrically seperated, and mount your neutrals on that bus bar, and you're golden.

[Gummi Bear]

I do sales for an electrical distributor(7 years,mainly Cutler-Hammer and GE) I answer questions like this all day long and apprentice to my father, a master electrician. Also you are right about the calc...kind of. :flipoff2:

:)


Which distributor? What part of the state?




Rusted - definitely a QO, no question about it. But, the ground looks like a bare #6. Pulling a solid #4 is darn near impossible (much cussing required) I'd venture a guess that it is attached either to a ground rod, or a cold water source.

[trampas]

Yes, if, the wire feeding from the main to the sub, and from sub 1 to sub 2, is also sized to handle 50amps over the entire length of both runs.

Why is this important? Because if the wire is not up handling 50 amps, it will act as a fuse and melt, likley catching on fire.

Ahh it's only important because i am frugal. :D Yep, i will make the additional 40' run from sub1 to sub2 in 6/3. Hence the overpurchase. Thx, Steve. :)

[trampas]

Well, that looks like a QO, right?

The green is the bonding location. Your bonding screw is not installed.

However, the red arrow looks like a #4 ground conductor to me, hooked directly to the nuetral bus. Also, it appears that you have both neutral and equipment ground conductors to the neutral bus.

I would make sure that the incoming ground, AND the equipment grounds go to a seperate bus bar mounted directly to the box, like mine in the photo I drew all the arrows on. Just make sure your neutral and grounds are electrically seperated, and mount your neutrals on that bus bar, and you're golden.

Ok, for the record, QO i'm not familiar with. You guys with your over -technicalized posts... just keep going that direction - it will never be TOO much information.

Rob, what's that allen-headed screw doing near/at/below the bonding location? The ground is a solid bare #6 running to a rod just outside this shop. The question i'm now having - seeing all the informative posts is; can i add "bars" to this sub-panel, or do i need another panel altogether to accomplish the sub-sub neutral-path ground-isolated configuration.

thanks.

[Gummi Bear]

Ok, for the record, QO i'm not familiar with. You guys with your over -technicalized posts... just keep going that direction - it will never be TOO much information.

Rob, what's that allen-headed screw doing near/at/below the bonding location? The ground is a solid bare #6 running to a rod just outside this shop. The question i'm now having - seeing all the informative posts is; can i add "bars" to this sub-panel, or do i need another panel altogether to accomplish the sub-sub neutral-path ground-isolated configuration.

thanks.


QO is a series of load centers made by Square D. Quality stuff.

The allen head screw is fastening the neutral/ground bar to the bonding lug (where the bare #6 is attached). Not something that you should ever need to monkey with. There should be a white wire attached to the ground bar from the feed at the main panel (I hope it's there)

About the ground bar. You can pick up an ground bar at an electrical supply house. Plop down at the counter, get your sack of popcorn (some supply houses will give out free popcorn, just a perk :D ) and order up. You can also pick up ground bar kits at your local HD or Lowes (HD carries Square D, I know for sure, Lowes never seems to have what I need, so I avoid it).

Remove the bare ground wires from the bar that is in the panel now, add a second ground bar and put them there. When you mount the ground bar, I'd suggest piloting the hole. A self tapping screw is no longer an approved ground means, so drill and tap the can (yes, you can tap that can for a 8-32 screw to mount the bar, just pay attention)

[trampas]

The allen head screw is fastening the neutral/ground bar to the bonding lug (where the bare #6 is attached). Not something that you should ever need to monkey with. There should be a white wire attached to the ground bar from the feed at the main panel (I hope it's there)

About the ground bar. You can pick up an ground bar at an electrical supply house. Plop down at the counter, get your sack of popcorn (some supply houses will give out free popcorn, just a perk :D ) and order up. You can also pick up ground bar kits at your local HD or Lowes (HD carries Square D, I know for sure, Lowes never seems to have what I need, so I avoid it).

Remove the bare ground wires from the bar that is in the panel now, add a second ground bar and put them there. When you mount the ground bar, I'd suggest piloting the hole. A self tapping screw is no longer an approved ground means, so drill and tap the can (yes, you can tap that can for a 8-32 screw to mount the bar, just pay attention)

Excellent, thanks for the post.

No, the feed from the earlier panel (found just today that it's the "home subpanel" this feed is from, i'm about to go and snap a picture and post it) does not have it's white wire going to the neutral bar. It goes (along with the black wire) directly to the 50a seen on the extreme right in the pic. So, i should rewire the configuration and put the white wire to the neutral bar, isolate and install a ground bar, but where do the other 2 feeders actually go now? Sorry, this is all investigatory for me!

[trampas]

Here's the picture of the house sub, in the garage.

The 40a dual-20 in the upper center is where i am pulling the new #6, the 10ga was pre-existing.

There is no ground isolation bar in this panel either.

Guess i'll be doing some significant changes throughout.

[Gummi Bear]

Here's the picture of the house sub, in the garage.

The 40a dual-20 in the upper center is where i am pulling the new #6, the 10ga was pre-existing.

There is no ground isolation bar in this panel either.

Guess i'll be doing some significant changes throughout.

Since your stuff is existing, it will technically be grandfathered (exempt) But, since you are making upgrades and changes, it is a good idea to do things like we've discussed. (these changes came about in the 1999 version of the NEC)

Keep the white wires on that bus bar. Get a ground bar, and remove all of the bare (and green) ground wires from the neutral bus, and attach them to the ground bus (along with the bonding ground wire, the bare #6 or so)

Explaining this stuff over the net is a lot more difficult than the actual task, if you were closer, I'd come over and drink some of your beer and walk you through the procedure. :D

FYI - if the white and black are attached to a breaker on the feed side, don't disconnect the white and put it on a ground bar, it is being used as a current carrying conductor, you'll cause a short, and a fantastic fireworks show.


If you don't already have one, pick up an electrical tester. For the money, something like a 'Wiggy' is good (~$20 at an electrical supply, or even HD) It is rated to test up to 600V, and is pretty failproof. ALWAYS test a circuit and verify that it is off before you work on it, and LOCK OUT and TAG OUT the feeding source (put a safety tag on it, to alert others that you are working on the circuit, a home made sign is better than nothing) Put your faith in NOBODY, always test a circuit, don't assume that it's off because someone told you so. Wear your safety glasses, copper fragments don't come out with a magnet (they have to cut and dig them out, it sucks)


I've been tangled up in 277V, and blew out all of my fillings while it threw me off the top of an 8' ladder (yeah it sucked, and could've killed me). I've also had copper shavings in my eye, none of it is fun. Just please, be safe.

[trampas]

Since your stuff is existing, it will technically be grandfathered (exempt) But, since you are making upgrades and changes, it is a good idea to do things like we've discussed. (these changes came about in the 1999 version of the NEC).

understood!

Keep the white wires on that bus bar. Get a ground bar, and remove all of the bare (and green) ground wires from the neutral bus, and attach them to the ground bus (along with the bonding ground wire, the bare #6 or so).

okay.. i'm with all of that.

Explaining this stuff over the net is a lot more difficult than the actual task :D

lol, i am finding this to be correct. :D

FYI - if the white and black are attached to a breaker on the feed side, don't disconnect the white and put it on a ground bar, it is being used as a current carrying conductor, you'll cause a short, and a fantastic fireworks show.

i'm not clear on this. Do you mean the white/black to feed my new sub - or the white/black that is feeding THIS panel?


If you don't already have one, pick up an electrical tester. For the money, something like a 'Wiggy' is good (~$20 at an electrical supply, or even HD) It is rated to test up to 600V, and is pretty failproof. ALWAYS test a circuit and verify that it is off before you work on it, and LOCK OUT and TAG OUT the feeding source (put a safety tag on it, to alert others that you are working on the circuit, a home made sign is better than nothing) Put your faith in NOBODY, always test a circuit, don't assume that it's off because someone told you so. Wear your safety glasses, copper fragments don't come out with a magnet (they have to cut and dig them out, it sucks).

Gotcha. I do own a Fluke 80 series, and have a 600v wiggly also.


I've been tangled up in 277V, and blew out all of my fillings while it threw me off the top of an 8' ladder (yeah it sucked, and could've killed me). I've also had copper shavings in my eye, none of it is fun. Just please, be safe.

I know, voltsxamps=watts. :goofball:

Thanks for all the help so far!

[steveh]

btt, this is a great thread for some of the q's on shop wiring

[trampas]

fwiw dept.

I eventually ended up leaving the neutral connected to the ground bus, at BOTH panels. Reason being is, i found the home is not really grounded. No REAL ground wire enters the ground i mean. Only pipe bond is present at the house, so when i pulled to the new shop, i continued the white/ground bus again, and ran a seperate ground at the shop w/ 2 8' ground rods connected with a single ground run. In a newer (grounded) home, i can see isolating the neutrals from start to finish.

:)