A few questions for you electrical gurus...

[aka Larry]

My new shop is finally up! Now I'm ready to start on the electrical and I have a few questions. FYI, in the past, I have installed breakers, outlets, switches, etc, but only with Romex, and I'll be using EMT and pulling individual strands in my new shop.

The plan:

For the main feed from the house to the shop I'll be hiring an electrician. I'm planning to use 2-2-2-4 AL MHF inside 1-1/2" conduit. 90A total. Yes, I know it can be direct burial, I want conduit just for extra protection. He will install the panel box in the shop and I will do the rest myself.

I have planned out the circuits to 80% load of the breaker rating. All the 120V outlets will be 20A. The first in the circuit will be a GFCI with the others daisy-chained off of that one.

I'm running (3) separate 240V circuits using #10 THHN wire. One for the air compressor (30A), one for the lift (30A) and one for a future (larger) MIG welder.

I have the chart for maximum wire fill of the EMT so I do know how many conductors I can safely pull.

I bought and EMT bender, but will not be doing offset bends. I'm using the EMT stand-off clips to make it easier on myself.


Now for my questions:

1. Using EMT, the conduit itself can be used as the ground path correct? If so, then for the 120V circuits can I run just two leads and use a grounding tail from each outlet to it's box? The reason I ask is because I'm wondering how the ground bar gets used in the panel box if I don't need a separate ground lead like I would have using Romex.

2. I'm planning to use #12 THHN stranded for the 20A receptacles and lighting circuits. Do you guys just wrap the wires on the screw terminals (like with solid wire) or use crimp-on terminal ends?

3. How far off the floor (per code) minimum do the outlets need to be?

4. Do you guys use those little stick on numbers to keep track of the wires in a particular circuit or do you use another method like with a continuity tester?

5. I don't have a fish tape so I will be buying one. I saw a fiberglass one in Lowes yesterday and thought that would be nice. Good idea or ****? FYI, I will have an outlet every 10 feet around the perimeter so the pulls aren't terribly long, if that matters.

6. Another EMT question, do I *need* to use the lube to pull the wires? It seems like it would just make a mess, but I don't know so I'm asking.


As always, thanks for the help!

 

[pattenp]

#1 - You need a grounding electrode (8' ground rods or ufer) at the shop which will hook to the ground bar in the panel. Make sure EMT is well grounded to the panel by sanding off some of the finish on the panel where the EMT connects.

Edit: Oh.. also the equipment ground from the house hooks to the ground bar in the shop panel. Remember to keep the neutral bar isolated from the ground bar in the shop panel.

 

[Alchymist]

Using the conduit as a ground is acceptable, I PREFER to pull a third green wire myself, just as an added precaution. All it takes is a bumped conduit to lose ground continuity, or a connection rusting up. Just personal preference, mind you, for peace of mind. YMMV.

 

[pattenp]

I totally agree with this.

Using the conduit as a ground is acceptable, I PREFER to pull a third green wire myself, just as an added precaution. All it takes is a bumped conduit to lose ground continuity, or a connection rusting up. Just personal preference, mind you, for peace of mind. YMMV.

 

[BigGMC]

My thoughts:

#2 Stranded can be put under screw heads if properly twisted, but a Sta-kon terminal makes it neater. I prefer back wire devices where there is a clamping plate.

#3 Dont know about hieght requirements in garage. For my build, i dont really plan on having any low outlets. All would be at bench height. I do plan on having some cieling boxes for power drops (retractable).

#5 Fiberglass fish is nice (non-conductive), but it is a bit larger diameter and the head is a bit bigger too. they are more $$. Metal is fine, you just have to mind the hot panel.

#6 THHN wires through EMT will pull very easy. You could probably just push the conductors through from outlet to outlet. No need for lube for the feeder ckts.

 

[Norcal]

My thoughts:

#2 Stranded can be put under screw heads if properly twisted, but a Sta-kon terminal makes it neater. I prefer back wire devices where there is a clamping plate.

Wire terminals (Sta-Kons®) are not listed to be used w/ wiring devices, devices w/ pressure plate connectors are best when stranded wire is used, but other then "push & pray" backwire terminals, all devices can be used w/ solid or stranded wire.

 

[truckn_r]

1 definately pull a seperate ground conductor.
2 stranded wire shall not be wraped around a screw, per code, 1 would crimp on terminals forks, or preferably buy the recepts with screws and tabs.
3 code does not specify elevation of the floor, housing is usually 16-18", while garages or industrial is around 48- 54" i set mine at 54" for future benches.
4 sticky numbers are nice, but not necessary, sometimes I use electrical tape bands to id wires.
5 fiberglass fish tape is nice whne working around live panels, steel fish tape pushes better though. some fiberglass fish tapes tend to "S" inside the conduit and not push as far.
6 lube is probably not needed, but I like yellow 77 because it stays on the wire andnot all over the floor, pluss im a one man show sometimes and pulling wire by your self is reallybtough without lube.
hope this helps.

 

[aka Larry]

My thoughts:

#2 Stranded can be put under screw heads if properly twisted, but a Sta-kon terminal makes it neater. I prefer back wire devices where there is a clamping plate.

#3 Dont know about hieght requirements in garage. For my build, i dont really plan on having any low outlets. All would be at bench height. I do plan on having some cieling boxes for power drops (retractable).

#5 Fiberglass fish is nice (non-conductive), but it is a bit larger diameter and the head is a bit bigger too. they are more $$. Metal is fine, you just have to mind the hot panel.

#6 THHN wires through EMT will pull very easy. You could probably just push the conductors through from outlet to outlet. No need for lube for the feeder ckts.

Thanks for the input so far guys. Can I use OTS terminal ends like I used in 12V stuff?

 

[Executive]

When using a metallic conduit system as the equipment grounding conductor, properly installed bonding bushings are required wherever a conduit terminates in a concentric or eccentric knockout.

Pull a green wire.

Chris

 

[BigGMC]

.....Norcal says you can't and truckn says you can use sta-kons........
The important thing is to use quality crimps and a quality pair of crimpers, not HF or other bargin bin types.
As I said before, I would use back wire devices.

 

[Mickey O]

I agree with pulling the extra ground wire. Now here's my 5 star recommendation, don't use anything less than 4 x 4 boxes and up size the conduit for the main runs, you need 1/2", use 3/4", it's not that much more expensive and there will come a time you'll be happy you did it. Quality back wire outlets are great, just don't get the cheap ones and avoid the Asian import junk (I'm seeing more and more Asian junk at the big box stores).

There are a pile of free conduit bending books on the internet if you're new to bending.


Here's the Klein one, click me











.

 

[rkevins]

I agree with pulling a green also consider a extra wire in you main runs or a pull string if that is legal) you will be glad you did when you have to add another wire. also you can't have to many receptacles when we did ours we put them 10' and now wish they were 5' or 6'

 

[FluxCore]

Yup, to most of the above, just adding clarity to "back wire devices"..You fersure want back wire outlets when using stranded conductors, or at least pre-bend and tin solder the strands if you plan to wrap them around the terminal screws on outlets...proper back wiring in an outlet designed it is best for stranded, tho

Friend, there are lots of el-cheapo 120V outlets that allow back wiring...The ones to avoid are the type where you push the wire in and it kinda sorta locks in place...Yup, avoid those because they offer only high resistance connections-those push in backwire types use a simple thin springy brass blade to' lock' the wire in place....What you want are "hospital grade", or "industrial grade"....These are designed for back wiring and provide a screw driven clamp that works especially well on stranded stuff with out tinning.

Proper outlet selection, and proper series wiring using stranded 12AWG will allow you to daisy chain a whole series of outlets with 20 amp capacity (providing only one is loaded at a time to that level)

Yeah, the hospital or industrial grade outlets are 5 bucks each, but you will never buy them again.


Oh, and if it was my shop, I'd wire it for 200 Amps and be done with it

 

[FluxCore]

I agree with pulling a green also consider a extra wire in you main runs or a pull string if that is legal) you will be glad you did when you have to add another wire. also you can't have to many receptacles when we did ours we put them 10' and now wish they were 5' or 6'

LOL, perhaps I'm ****, but I placed duplex outlets on every other wall stud...32" centers, 48" high...All 20 amp hospital grade.

I freaking HATE needing to STOP to rig an extension cord when I'm working on a project. If I'm near a wall, I want an outlet in arm's reach, yaknow?

I did the same with the ceiling...it's 8" high...shop is 24X26, but there are 22 duplex oulets in the ceiling

But that's just me.....If ever I hire a drywaller, he is gonna cuss me, huh?

 

[Speedy Petey]

Wire terminals (Sta-Kons®) are not listed to be used w/ wiring devices,

Do you have anything to support this claim?

 

[FluxCore]

Oh, and pull a green thru every leg....bond it at every outlet and fixture BECAUSE you are running inside conduit and metal boxes....I've experienced hot conduit...shunt that potential to Earth and not you.

I finally found the cause...it was an improperly stripped black that had a nick in the insulation.....when the outlet was pulled out of the box, the nick closed up, but when you forced the outlet back in the box the nick opened up and shorted to the back of the metal box lighting the whole run up....made my hair crackle whenever I touched a box or run of conduit....I finally saw a tiny black spot in the metal box and then looked to see the black lead insulation was nicked and only opened when outlet was forced into box and mounted.

 

[Charles (in GA)]

Don't use stand off clips on the walls, that looks tacky. I use them only in locations where nothing else works, or it is mostly out of sight If doing enough, either learn to do offsets, or easier, buy offset box fittings for the EMT to the box.

Offset box to EMT fittings

As far as bending conduit goes, HERE is a good document on bending EMT.

Charles

 

[Mickey O]

Wire terminals (Sta-Kons®) are not listed to be used w/ wiring devices

Do you have anything to support this claim?

I sure hope he's wrong*, I've used thousands of those connectors inside electrical panels for industrial controls, do I have to go take them off?











* Actually I know he's wrong

 

[wellpoison]

i agree with everyone else, pull a green ground, its just an added caution incase of rust, loose connection etc. plus it doesn't count against the number you can pull in a conduit or splice in a box (dont think you will have that problem anyway).

you can wrap the stranded around the terminal or use the crimp type.

i would put your receptacles about bench height, think about all the stuff that will be sitting or leaning on the walls so your going to want to use them without moving anything, i believe if you keep them high enough you wont have to use tamper resistant ones either. hopefully someone can chime in on that exact height.

you wont need any soap, most likely you wont even use the fish tape too much either.

offset bends are pretty easy once you get the measurements right, if you have a smart phone the app called ibend pipe is really helpful. i would get it even if you dont do offsets.

 

[Executive]

i agree with everyone else, pull a green ground, its just an added caution incase of rust, loose connection etc. plus it doesn't count against the number you can pull in a conduit or splice in a box (dont think you will have that problem anyway).

you can wrap the stranded around the terminal or use the crimp type.

i would put your receptacles about bench height, think about all the stuff that will be sitting or leaning on the walls so your going to want to use them without moving anything, i believe if you keep them high enough you wont have to use tamper resistant ones either. hopefully someone can chime in on that exact height.

you wont need any soap, most likely you wont even use the fish tape too much either.

offset bends are pretty easy once you get the measurements right, if you have a smart phone the app called ibend pipe is really helpful. i would get it even if you dont do offsets.

Every conductor in a conduit "counts" as part of the fill calculation. The EGC does not count toward derating as it is not a current carrying conductor.

If you don't know what you are talking about don't give advice.


I'm new here and like the forum but I am surprised at the volume of wrong advice in the electrical section. I always recommend hiring a pro for electrical work, probably not the best idea on a DIY forum. My recommendation here is to know what you can do and know what you can not. Be careful

Chris

 

[MrMark]

There's tons of wrong advice on every subject on every forum. You have to weed through all the bad advice to find the gems. Electrical forum is no different except there seems to be a haughty attitude on this forum sometimes.

 

[Speedy Petey]

There's tons of wrong advice on every subject on every forum. You have to weed through all the bad advice to find the gems. Electrical forum is no different except there seems to be a haughty attitude on this forum sometimes.

I beg to differ. The consequences of a botched electrical job are FAR more serious than lets say plumbing or painting. Think about it.
It's one of the only things that even a seemingly minor mistake can kill you.

Too many people loose sight of that, or stupidly ignore it all together.

If this is haughty I am FINE with that.

 

[aka Larry]

OK guys, let's not get out of hand.

Like I said, I am hiring an electrician for a portion of the job. For the DIY part I have consulted him and he has pointed out a few items that I need to meet the code. Like you guys, he also recommends pulling one green wire for insurance, and I'm OK with that.

Don't worry, I plan to have him check all of my work before it's all done.

 

[sberry]

I'm new here and like the forum but I am surprised at the volume of wrong advice in the electrical section. I always recommend hiring a pro for electrical work, probably not the best idea on a DIY forum. My recommendation here is to know what you can do and know what you can not. Be careful

I will whole heartedly disagree. Hiring a contractor is no guarantee of anything especially for the uninformed and second there are thousands of installations done correctly from these forums, hundreds of thousands now have some concept further than a 12 on a 20, thousands now know where the agree wire goes vs doing it the way they did it yesterday and 3rd,,, and this is a big one,,, could include myself here on occasion but there are enough know it alls that people must not listen to in real life that if a guy slips up with a period someone lets him know.

Ideally is to correct without making it personal, some guys here good at that and there are at least a half a dozen regulars frequent this forum that are legitimate masters.

I am going with Norcal on this, in common residential wiring they are not to be used, this is different than many industrial controls. Second to that Norcal is current, he has been to the school, bought the books, has read them,,, in detail, I believe holds a masters. If I was at the casino would take that bet with odds.

As for outlets, I agree back stabs are out for the most part, I got no use for them, clamps are the best but where guys got box space rarely install more than a 50 cent recept. I must have 300,,, maybe more, maybe closer to 500 in service and can't recall the last time I replace a faulty one and have several that are extremely high duty/service cycle on work benches, used thousands of times a year and as I can recall the only replacement I have had was physical damage or poor appearance. In a common home garage all this doesn't add up to a pinch of ****. I do like better recepts on occasion in remodel, etc, romex and tight boxes where there is no room for pigtails for feed thrus, in a 4x4 not much of an issue.

As for the guy with hot conduit, obviously something was missing,,, might not have been right by the careless installer anyway and rust and even loose connects are not much of an issue in fixed garage wiring. My building is steel, used the pipe for most of it, on occasion I run a green for special circumstances. Recently I actually pull it and add a green to a circuit where the emt went under floor, maybe it never rusts off,,, who knows, its something I cant see, probably not much of an issue as some of it was gfci for recepts, I recall there was a light circuit,,, but again this is all steel with boxes and pipe bolted to building. It was free as we had the box open, while we were there we put in a green wire we have in stock.

 

[MrMark]

I beg to differ. The consequences of a botched electrical job are FAR more serious than lets say plumbing or painting. Think about it.
It's one of the only things that even a seemingly minor mistake can kill you.

Too many people loose sight of that, or stupidly ignore it all together.

If this is haughty I am FINE with that.

yada yada yada. Electrical work is the most forgiving medium in the world, on an electrician level. Stuff is messed up beyond belief by electricians every day and yet the lights still turn on. A bad brake job will kill you just the same as an open neutral and yet we don't see the same high and mighty on the other forums.