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eHam Forums => Station Building => Topic started by: K3GM on February 25, 2019, 01:11:04 PM



Title: 240VAC passing thru 120VAC outlets..
Post by: K3GM on February 25, 2019, 01:11:04 PM
I'm wiring my shack in a home we moved into recently.  I've got ten surface mounted duplex outlets in a line along a concrete basement wall.  #1 is closest to the panel and #10 is farthest away from the panel.  I'm using 1/2" EMT, outlets are spaced about 16" apart.

Question: If outlet #8 is designated for 240VAC, and both voltages are in the same conduit, can I pass the 240V THHN wires behind each outlet until I get to outlet #8?


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: W9FIB on February 26, 2019, 02:41:19 AM
Sure with 2 comments...

All wire must be rated at 300V. Most THHN in the big box stores is rated at 600V.

And as long as the conduit does not have too many wires in it. There is a maximum fill allowed by NEC. Here is a link to a handy fill chart:

http://www.elliottelectric.com/StaticPages/ElectricalReferences/ElectricalTables/Conduit_Fill_Table.aspx (http://www.elliottelectric.com/StaticPages/ElectricalReferences/ElectricalTables/Conduit_Fill_Table.aspx)


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: K3GM on February 26, 2019, 08:00:08 AM
Thanks, Stan.  I am under the max. allowable conductors in the EMT.  Ok, here's another question:  I am assuming (perhaps in correctly) that I can share the same 12awg, green ground wire in both the 120 and 240 outlets provided the wire guage meets the  current requirements?


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: KX4QP on February 26, 2019, 08:18:04 AM
Thanks, Stan.  I am under the max. allowable conductors in the EMT.  Ok, here's another question:  I am assuming (perhaps in correctly) that I can share the same 12awg, green ground wire in both the 120 and 240 outlets provided the wire guage meets the  current requirements?


Code requirements aside, I'd be cautious doing this -- at the least, I'd check that the ground those are connected to is actually a good ground with low resistance.  If you should get a crossover on the 240V, and have a high resistance in the ground (bad connection at the stake, dry clay around the stake, etc.), you'd wind up with 240V on the chassis of everything grounded to any of the 120V outlets.  Use of GFCI on all the outlets would help here, in that a ground crossover would be instantly cut off at the outlet with the problem.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: K3GM on February 26, 2019, 11:01:06 AM
I can run a separate ground wire for the 240VAC outlet, but both grounds would be essentially connected back at the panel.  While not wired yet, the plan is to use either a GFCI breaker (this is a new dedicated circuit) or a GFCI outlet at the beginning of the chain of plugs.
Here's a shot of the work.
(https://i.postimg.cc/437jC5yp/20190226-140128.jpg)


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: AA4PB on February 26, 2019, 12:06:42 PM
Most of the outlets I've seen have the green ground screw tied to the metal mounting tabs. When you mount them in a metal box, the box gets connected to the grounding conductor. Since you are using metal conduit, all the boxes are electrically connected via the conduit. That means that even if you use separate grounding conductors for 120V and 240V outlets, both types of outlets have their grounds tied together via the conduit anyway. I don't see any issue with using a single grounding conductor.



Title: RE: 240VAC passing thru 120VAC outlets..
Post by: KX4QP on February 26, 2019, 01:45:19 PM
I can run a separate ground wire for the 240VAC outlet, but both grounds would be essentially connected back at the panel.  While not wired yet, the plan is to use either a GFCI breaker (this is a new dedicated circuit) or a GFCI outlet at the beginning of the chain of plugs.

The GFCI outlets I've seen protect only loads connected on their own sockets; to protect the whole string you'd need either all the outlets to have GFCI or you'd need a GFCI breaker.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: KB2WIG on February 26, 2019, 03:08:51 PM


You can use a GFI breaker, or one GFI receptacle. The GFI receptacle will protect receptacles 'past' it on the same ckt, if you wire it correctly.

Check this out.

https://www.do-it-yourself-help.com/gfci-outlet-wiring-diagrams.html


Be careful accepting information online; how do you know I'm not a wazoo when I tell you things?

Check this out,

https://www.mikeholt.com/instructor2/img/product/pdf/1292432628sample.pdf


klc


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: W9FIB on February 26, 2019, 07:41:47 PM
Most of the outlets I've seen have the green ground screw tied to the metal mounting tabs. When you mount them in a metal box, the box gets connected to the grounding conductor. Since you are using metal conduit, all the boxes are electrically connected via the conduit. That means that even if you use separate grounding conductors for 120V and 240V outlets, both types of outlets have their grounds tied together via the conduit anyway. I don't see any issue with using a single grounding conductor.

AA4PB is correct. The EMT bonds the boxes together for the ground provided that it is EMT properly installed from the breaker panel to the last box on the end. Green grounding wires with the green screw are used to tie the ground terminal on the device to the box itself. The cover holding the device being attached with screws to the box is not considered a proper ground per NEC requirements. The big box stores sell these ground wires in a package. Low cost and time saving compared to making your own and buying the green screws.

Per recent code revisions, Arc Fault Circuit Interrupters (AFCI) may be required for most new wiring installations. You would need to verify this with your local building inspector for this application. In my jurisdiction as of 2015 it was not required for my new office/shack at that time. However other parts of my house were required to have them in 2015. But this requirement has been changing with each new NEC code book update. It is worth a phone call. Otherwise GFCI is a good item to use. Info here for those who want to know more: https://www.ecmweb.com/content/arc-fault-detection-your-questions-answered
 (https://www.ecmweb.com/content/arc-fault-detection-your-questions-answered)
BTW Nice looking install based on your pic.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: K3GM on February 26, 2019, 08:12:32 PM
Good info.  Thanks, Stan and everyone.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: KX4QP on February 27, 2019, 08:37:58 AM
From what I read in the provided link, an AFCI doesn't replace a GFCI -- you really need both for safety.  GFCI protects against hot wire contact (shuts off if as much as 10 mA flows outside the protected load circuit), while an AFCI protects against an entirely different kind of fault at much higher characteristic currents.  Then there's the PFCI, which seemingly can only be installed in the receptacle -- but it looks complicated to get AFCI, GFCI, and PFCI protections all on the same receptacle.  You seemingly have to choose which two you'll install (either AFCI or GFCI at the box, and either GFCI or PFCI at the outlet).

This looks like it's heading toward another case of codes wanting to make us so safe we can't do anything.  If code requires all of AFCI, GFCI, and PFCI, there'll be no place you can plug anything in (at least until they start selling receptacles, likely for $100 each, that combine the functions of GFCI and PFCI).


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: K6JH on February 27, 2019, 03:35:06 PM
PFCI? I can't seem to find that one. Can you clue me in?


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: W9FIB on February 27, 2019, 04:04:27 PM
PFCI? I can't seem to find that one. Can you clue me in?
Power Fault Circuit Interruper


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: K6JH on February 27, 2019, 04:52:49 PM
PFCI? I can't seem to find that one. Can you clue me in?
Power Fault Circuit Interruper

Oh, so they are basically looking at the voltage drop to find high resistance in the wiring. Doesn't look like they are generally available yet, or required.

They're gonna take all the fun out of playing with electricity... ;-)


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: KD0REQ on February 28, 2019, 12:06:54 PM
conduit is not recognized as a protection ground in a life-safety environment. corrosion and loose connections break it. as a personal note, you can always exceed the code requirements. what I'd do is pass a over-rated ground wire and use that for all the protection grounds. thus, no ground loops, no differential currents.

the AFCI also has GFI capabilities, and that's now the NEC code standard for all liveable spaces, so don't chain them. you'll have false trips till Hell freezes over.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: W9FIB on February 28, 2019, 12:26:14 PM
conduit is not recognized as a protection ground in a life-safety environment. corrosion and loose connections break it.

Reread the NEC code book. Or site the code that has changed. To my knowledge general electrical construction with EMT when properly installed and bonded is acceptable for ground. Also outlets in a basement unless specifically designed for certain types of special equipment are nothing special.

And btw, a green ground wire can corrode and/or loosen over time, or be physically damaged as well. Same is true for any wires in the circuits.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: K3GM on March 01, 2019, 11:08:57 AM
Update:  My local big box home store had 20A GFCI  outlets for $18.00, and a std 20A breaker for $4.50.  A GFCI/AFCI 20A breaker was nearly $50.00, so I went with the simple GFCI outlet and 20A breaker.  Thanks all for your inputs.  I'll begin pulling wire shortly.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: N9TGR on March 03, 2019, 09:41:52 AM
You are going the right way about it, use #12 thhn and a separate ground wire bonded to your 4x4 box ,there is a 10/24 screw hole in each box for the ground, Splice and pigtail a ground for each outlet . The 240v line will use the same ground wire ,, on my install I used a DP and single pole toggle switch to power down everything when I am finished operating, You could leave one duplex outlet unswitched along the chain if you want to leave your PC running. Switch the hot wires only and never the neutral.
Nice to see people doing it the right way.

Andy N9TGR


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: KB2WIG on March 03, 2019, 10:10:49 AM



You could reall walk tall if you ran #10 AWG in your 20 A ckt.

KLC


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: W9FIB on March 04, 2019, 02:56:50 AM
You could reall walk tall if you ran #10 AWG in your 20 A ckt.
KLC

Waste of money and conduit fill space on such a short run. Its like using LDF50 hardline instead of RG-8 for a 10-15' run on HF.

Plus installing #10 AWG THHN on 20A devices is a pain in the rear. So why go through the aggravation for no gain?

Remember also in NEC code, #12 AWG is already down rated from actual physical ampicity.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: KB2WIG on March 05, 2019, 05:54:07 PM

"  So why go through the aggravation for no gain?  "

Cause it builds character.... ..     Stan, you're probably right, but I've been know to do things the hard way.

From the photo, it looks like an easy job. One can use stranded THHN if it makes things easier. Just make sure whatever you decide will fit onto the terminal screws.

Jim Brown has a nifty website which deals with a lot of noise and RFI issues.This is where the idea of the 10 AWG replacing 12 AWG came from. (Although I did wire my wheel grinder in the garage with 10/2)

http://www.audiosystemsgroup.com/publish.htm

The following may be of interest.
http://www.audiosystemsgroup.com/GroundingAndAudio.pdf

http://www.audiosystemsgroup.com/InfoComm-Grounding2012.pdf

I'll go to places like the homely despot or lowleys for wire or boxes. For breakers, recepticles etc., go to a electrical supply house. You are less likely to be sold crap, although the prices are going to be higher, as the guy behind the counter knows you are not going to spend a few $K every mounth or so. Just don't ask for outlets, as the counter person will secretly hate you.

klc

If I had some LDF50 hardline, I'd be using it......


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: W9FIB on March 05, 2019, 07:38:29 PM

"  So why go through the aggravation for no gain?  "

Cause it builds character.... ..     Stan, you're probably right, but I've been know to do things the hard way.

From the photo, it looks like an easy job. One can use stranded THHN if it makes things easier. Just make sure whatever you decide will fit onto the terminal screws.

Jim Brown has a nifty website which deals with a lot of noise and RFI issues.This is where the idea of the 10 AWG replacing 12 AWG came from. (Although I did wire my wheel grinder in the garage with 10/2)

http://www.audiosystemsgroup.com/publish.htm

The following may be of interest.
http://www.audiosystemsgroup.com/GroundingAndAudio.pdf

http://www.audiosystemsgroup.com/InfoComm-Grounding2012.pdf

I'll go to places like the homely despot or lowleys for wire or boxes. For breakers, recepticles etc., go to a electrical supply house. You are less likely to be sold crap, although the prices are going to be higher, as the guy behind the counter knows you are not going to spend a few $K every mounth or so. Just don't ask for outlets, as the counter person will secretly hate you.

klc

If I had some LDF50 hardline, I'd be using it......

If I would apply that philosophy to my designs/installs...I would lose money with a low bid, or not get the contract as those who would do it right could bid lower if I wanted to actually make money. Both from a material cost and a labor cost.

But if your happy wasting time and money, go for it. NEC codes are to make things safe. Going beyond what is needed is up to you and your expense.

Just make sure that #10 wire is securely tucked under those tiny screws or it will fail inspection. And I have seen a lot of sloppy work get tagged.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: K3GM on March 05, 2019, 08:53:33 PM
For the record, I'm pulling #12 THHN wire.  The most power hungry thing in my shack is an HF amp which runs at 240V, 9A max.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: WB4SPT on March 10, 2019, 01:36:12 PM
conduit is not recognized as a protection ground in a life-safety environment. corrosion and loose connections break it. as a personal note, you can always exceed the code requirements. what I'd do is pass a over-rated ground wire and use that for all the protection grounds. thus, no ground loops, no differential currents.

the AFCI also has GFI capabilities, and that's now the NEC code standard for all liveable spaces, so don't chain them. you'll have false trips till Hell freezes over.

IF you do run a bonding/grounding conductor, it must be attached to each box.   You can't run green or bare wire thru a box and not attach it, EVEN if you use EMT.  I always run a green conductor within EMT.  I don't trust the mickymouse conduit grounding provisions.   


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: N8FVJ on March 16, 2019, 04:05:23 AM
Most of the outlets I've seen have the green ground screw tied to the metal mounting tabs. When you mount them in a metal box, the box gets connected to the grounding conductor. Since you are using metal conduit, all the boxes are electrically connected via the conduit. That means that even if you use separate grounding conductors for 120V and 240V outlets, both types of outlets have their grounds tied together via the conduit anyway. I don't see any issue with using a single grounding conductor.


Technically, you need grounding bushings at each conduit connector and having a ground wire to connect to each electrical box grounding bushings. Cheaper to run the ground wire.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: W9FIB on March 16, 2019, 07:13:01 AM
Most of the outlets I've seen have the green ground screw tied to the metal mounting tabs. When you mount them in a metal box, the box gets connected to the grounding conductor. Since you are using metal conduit, all the boxes are electrically connected via the conduit. That means that even if you use separate grounding conductors for 120V and 240V outlets, both types of outlets have their grounds tied together via the conduit anyway. I don't see any issue with using a single grounding conductor.


Technically, you need grounding bushings at each conduit connector and having a ground wire to connect to each electrical box grounding bushings. Cheaper to run the ground wire.

No you don't. And its not cheaper because in a branch circuit, the EMT fitting nuts bond the conduit to the box. Bonding bushings are required only if the EMT is interrupted by a non conducting material and a green wire run to compensate. And with todays copper prices, adding unneeded wire only adds to the expense with no real purpose other than to look good for those who do not know or understand the NEC code requirements.

Service entrance metal conduit needs to be bonded with bonding bushings. But that's a whole different set of rules than branch circuits.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: KD6VXI on March 22, 2019, 08:50:55 PM
conduit is not recognized as a protection ground in a life-safety environment. corrosion and loose connections break it.

Reread the NEC code book. Or site the code that has changed. To my knowledge general electrical construction with EMT when properly installed and bonded is acceptable for ground. Also outlets in a basement unless specifically designed for certain types of special equipment are nothing special.

And btw, a green ground wire can corrode and/or loosen over time, or be physically damaged as well. Same is true for any wires in the circuits.

In California, you are NOT allowed to use the 'sheath' as ground, except in cases EXPLICITLY allowed.  Like MCH style cable.  That is isolated ground mc cable.

He's right, you are wrong.  At least in California. 

No, I'm not going to go to the truck and get my code book out to cite the code.  You're more than welcome to Google it.  I inky have to prove an I spector wrong, and then they have the AHJ clause to fall back on, 'as interpreted'.


THAT BEING SAID!  Yes, years ago it WAS within code to use the pipe / sheath as ground.  Problem was, oxidation.  Doesn't take much oxidation to have a voltage potential in a fault condition.  Doesn't take many volts to kill you, either.



As to the question of grounding conductors being shared.  This is done all the time.  Code states that you must use wire with an insulation breakdown greater than the highest voltage in the pipe.  You also must use a grounding conductor bug enough to carry the fault current of the largest conductor in the system.  IE, if you have a 240 / 30A plug, you must use a ground wire big enough for the 30A plug, even if you have 3 other 15A circuits in the pipe.

In my jurisdictions, we also MUST ground tail each metal box.  This means a seperate ground wire from the small screw hole in the back of the box tied in to the ground system.  This is SPECIFICALLY because we aren't allowed to use the emt / sheath as ground. Then a ground wire also to each plugs ground screw tied in with the same wires.  As you can see, ground is a big deal.

If you use stranded wire in the pipe you may not use that to each plug.  The connection to the plugs should be in hard drawn copper.  Some jurisdictions also require each plug to have pigtails for each conductor as well.  That provides a point of disconnect so you can work on a single plug without taking the whole system down.

Since your residential, that means you must have 120 volt wire.  We have split phase 120 to make 240 here in residential USA.  In commercial (and I guess limited residences, I have 3 phase in my garage and some places like Arizona also have 3 phase for AC units) you can have 120/208 circuits.

Almost all wire sold in spools is either THHN/THHN-2 or THWN/THWN-2.  In Los Angeles, I have to use the THWN-2 rated wire.

Otherwise, you look good.  I'd use a seperate gfi on each plug.  Then use an AFCI breaker in the panel.  This will help with nuisance trips.  If you plan on high power, go with the AFCI breakers that have the yellow button.  They are RF hardened.

You can use turns through ferrite to quench RF getting into the AFCI as well.  I would NOT recommend using disc caps, as those can break your gfci protection.  And as they age, they can and do cause leakage current that again will nuisance trip the gfi system.

Hope this helps / clarifies.

--Shane
KD6VXI


information given based on 2017 NEC / CEC. 


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: KD6VXI on March 22, 2019, 08:52:28 PM
On bonding bushings, you also must use them on a concentric knockout.  That way the pipe is still at ground potential if the concentric breaks free.

Again, it's the whole not being able to use the pipe / sheath as a ground thing.  The code is pretty freaking clear about it.

--Shane
KD6VXI


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: W9FIB on March 23, 2019, 01:57:53 AM
information given based on 2017 NEC / CEC. 

We are not talking MC cable sheath here. But rather rigid EMT conduit. A whole different class of electrical construction.

Citation please.

I do not find this information being applicable to EMT in my copy of the NEC. With that said, local areas can go beyond the national standard. So a citation of where you got this information would be helpful to teach others new things that have been recently changed by the NFPA.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: W9FIB on March 23, 2019, 02:39:53 AM
On bonding bushings, you also must use them on a concentric knockout.  That way the pipe is still at ground potential if the concentric breaks free.

Again, it's the whole not being able to use the pipe / sheath as a ground thing.  The code is pretty freaking clear about it.

--Shane
KD6VXI

Correct. Which is why areas that commonly use concentric knockouts are most common around service entry equipment and do fall under different construction methods. I even mentioned that earlier. The reason being that the cable size coming into the service entrance equipment can vary in size based on the service rating. So it stands to reason that the entrance piping can vary in size to accommodate the various size service entrance conductors. Flexibility at the expensive service entry equipment is vital.

Another reason for various service entry pipe sizes has to do with the bending radius of the conductors. Using too small a pipe could mean using LBs, elbows, etc. that provide too small of a bending radius for the conductor and must be upsized to accommodate a proper radius. So again flexibility at the expensive service entry equipment is vital.

However, I rarely see outlet boxes have this type of knockout anymore. They come with standard sized holes for direct mounting of EMT fittings. Therefore there are no rings to break so the bond does not break. And if more room is needed, the conduit is upsized and the proper sized boxes are then used that accommodate the correctly sized conduit.

However, you would be correct if you did use such a type of box in place of standard hole size knockout boxes. I avoid them. That way I do not have an added expense by using materials not specifically suited for the job at hand, or extra materials and labor to compensate for using the wrong boxes for common outlets.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: NA4IT on March 23, 2019, 05:52:21 AM
I am a disabled / retired master electrician. Here is what I did regarding conduit and grounding.

1) I ALWAYS ran a green or bare copper ground inside the conduit, bonded to every box under the ground screw location built into the box, with a tail left hanging to connect to grounding screws of outlets and switches. Conduit box fitting can loosen in time.

2) I usually ran solid THHN wire because it's easier to wire. I NEVER used to "push in" connections on the back of an outlet or switch. I always used the screws, and some devices had a hole you put the wire into and then tightened the screw.

3) As long as the 240 circuit is "3 wire" (two hots and a ground) I'm OK with a shared ground. If it is a "4 wire" 240 circuit make sure you size the neutral wire properly (enough to carry the amp rating of the breaker).

4) If the run is short, sometimes you can save money by buying NM cable (12-2w/G) and stripping off the sheath, then putting just the wires in the conduit.

Disclaimer... I offer this as information only. YOU are responsible for how you use this information and the safety of your person.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: KD6VXI on March 23, 2019, 07:09:43 AM
Have you looked at a 4S box lately? I just bought a case, and they have concentric knockouts. If yiu used half inch, you'd need bond bushings.

I can't see from his pictures what types of boxes he has. 

Even a handi box can have concentrics.

Im not getting into a pissing contest with you.  As I stated, I based my statements in what I've experienced as a solar installer and electrician for the last 5 years plus in my jurisdictions (California, in many cities and various counties both northern and Southern).

You want to base your answers in a poor homeowner arguing with his insurance company about what he read on the internet, that's fine. What I told him WILL pass code and an inspection almost universally.  Your answer, better be prepared for a fight around here.

That green run of wire is SO expensive....!


Have a good weekend, done with arguing.


--Shane
KD6VXI


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: KD0REQ on March 23, 2019, 10:59:58 AM
ground wires must be able to carry all the potential current rated for all conductors in the box. so, if I didn't misread a post further up... you cannot rely on an existing 14 or 12 gauge ground wire for a 115 volt circuit AND a 240 volt circuit in the same run.

either use an oversize ground lead, or pull a new ground with the new circuit. assuming 20 amp 240 volt and existing 15 amp 120 volt, you need to have protective ground capable of 35 amps carrying current, which is halfway between a #8 and #10 AWG. size up to the #8 and party on.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: K3GM on March 23, 2019, 12:11:36 PM
Thanks again everyone for the advice, debate, etc.  Just to provide some info, the boxes are standard Steel City, 1 gang, old work boxes that are available at the Home Depot for $.99 each.  Each box is not loaded with a ground screw on the inside back of the box.  I will run a ground wire with the hot and neutral conductors. The 240VAC box will be the 5th box from the panel, so it is simple to run a separate and continuous green wire to that box.  I purchased a standard breaker at the panel rather than an AFCI/GFCI breaker as guys in my club are having tripping problems with them.  Experiments are underway to see what can be done to harden them by way of ferrite or possibly something else.

But here's a question:  There is a recommendation by Scott, NA4IT to use NM cable (aka. Romex) and strip the jacket off.  This is a great idea and certainly cheaper than THHN.  But the jacketed conductors inside NM cable aren't identified in any way, and I thought and read somewhere that this wasn't allowed because of that (not trying to sell you short, Scott). Any comments before I buy the wire?


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: AA4PB on March 23, 2019, 12:54:22 PM
The conductors inside Romex cable have color coded insultation on them. 12/3 with ground will have a Red, Black, White and bare (ground) conductor.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: K3GM on March 23, 2019, 01:57:35 PM
I realize that, Bob, but the wire conductors jacket inside NM cable has no identifying nomenclature on it to show that it conforms to a particular set of parameters; like THHN or THWN wire has on its jacket.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: W9FIB on March 24, 2019, 02:43:13 AM
Have you looked at a 4S box lately? I just bought a case, and they have concentric knockouts. If yiu used half inch, you'd need bond bushings.

I can't see from his pictures what types of boxes he has. 

Even a handi box can have concentrics.

Im not getting into a pissing contest with you.  As I stated, I based my statements in what I've experienced as a solar installer and electrician for the last 5 years plus in my jurisdictions (California, in many cities and various counties both northern and Southern).

You want to base your answers in a poor homeowner arguing with his insurance company about what he read on the internet, that's fine. What I told him WILL pass code and an inspection almost universally.  Your answer, better be prepared for a fight around here.

That green run of wire is SO expensive....!


Have a good weekend, done with arguing.


--Shane
KD6VXI

When you bid a job, making extra cost for yourself is self defeating.

Never said you CAN"T get that style of box, simply that you can also get boxes just as cheap without the concentric knockouts and avoid the extra costs.

Its the difference between being an installer that will use anything and a contractor maximizing profit on a bid project and following the rules.

BTW...never did see your citation of the NEC that you were so proud of.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: W9FIB on March 24, 2019, 02:49:17 AM
I realize that, Bob, but the wire conductors jacket inside NM cable has no identifying nomenclature on it to show that it conforms to a particular set of parameters; like THHN or THWN wire has on its jacket.

That is correct as the NM cable is specified and built as a cable assembly. So the ratings apply to the assembly, and the interior parts do not require the same markings as THHN which is installed as an individual component.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: W2RWJ on March 25, 2019, 04:08:59 PM
(https://i.postimg.cc/437jC5yp/20190226-140128.jpg)

Are you going to run into box fill issues between the device, grounding wire, the wire nuts, and pass-through cabling?


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: AA4PB on March 25, 2019, 05:01:21 PM
I realize that, Bob, but the wire conductors jacket inside NM cable has no identifying nomenclature on it to show that it conforms to a particular set of parameters; like THHN or THWN wire has on its jacket.
Is the inspector going to pull the wires out of the conduit to check for the proper markings? If you need a few inches of THHN for a jumper do you have to make sure you cut a piece that includes the marking? Around my area you can use a white wire for a hot lead if you mark each end with a piece of black tape or a black magic marker. I've never seen anyone worry about the markings on the wire - but every area is different.

In my area places like Home Depot sell THHN by the foot off a reel although for as much as you will probably need it might be less expensive in bulk rolls.

It's probably going to be a problem pulling around those four 90's going around the post.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: K3GM on March 25, 2019, 08:26:56 PM
......It's probably going to be a problem pulling around those four 90's going around the post.
The photo doesn't show it well, but there are inside and outside pull elbows at the four corners.

Your other comments regarding jacket nomenclature are certainly valid.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: K3GM on March 25, 2019, 08:42:13 PM
Are you going to run into box fill issues between the device, grounding wire, the wire nuts, and pass-through cabling?

Remains to be seen.  This is a second residence, so I work on it sporadically when I'm there. The only wire nut in each box will be a Greenie for the ground run, while each loop outlet hot and neutral screws will serve as the "gozinta" and "gozouta" for each box.


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: K3GM on April 20, 2019, 04:13:34 PM
Follow up:
If I could have a do-over.... The "handy boxes" I used were way too small for four 12 guage wires, two conduit fittings, and a greenie wire nut for grounding.  It was impossible to pass the 240V wires thru the boxes.  While I was able to cram everything in, I should have used 4x4 boxes with a cover for one duplex outlet.  They would have provided adequate room for everything plus the 240V wires.  I know this because the #1 outlet which holds a GFCI outlet would not fit in the handy box.  I replaced it with a 4x4 box, and then getting everything in was a breeze.  So I'm going to run a separate conduit for the 240V line.  Live and learn I guess....


Title: RE: 240VAC passing thru 120VAC outlets..
Post by: W3TDH on June 17, 2019, 06:53:59 PM
conduit is not recognized as a protection ground in a life-safety environment. corrosion and loose connections break it. as a personal note, you can always exceed the code requirements. what I'd do is pass a over-rated ground wire and use that for all the protection grounds. thus, no ground loops, no differential currents.

the AFCI also has GFI capabilities, and that's now the NEC code standard for all liveable spaces, so don't chain them. you'll have false trips till Hell freezes over. 

There is no gentle way to say this.  You are misinformed. 

The only place that Electro Metallic Tubing cannot serve as the only Grounding (Bonding) Electrode Conductor is in patient care areas of healthcare facilities.  All patient care areas of such facilities must have two independent Equipment Grounding Conductors either of which would otherwise be adequate on their own.  There are several places you cannot use EMT at all but that is a totally different situation.  The only application that allows the wire Equipment Grounding Conductor to not be bonded to the box through which it passes is were the wire EGC is serving Isolated ground receptacles.  Those are only used to supply equipment that is so sensitive to electrical noise on it's ground that it will cause operational failure. 

AFCI Breakers do provide Ground Fault Protection of Equipment because they will open on any leakage current which exceeds 30 miliamperes.  The required trip level for Ground Fault Circuit Interrupters is 5 miliamperes.  So unless you are talking about one of the combination AFCI GFCI breakers; which are now readily available even at big box stores; the two types of circuit breakers serve different functions.  Since an unfinished basement is not defined as an living area by the building codes they are not required to have AFCI protection.  All unfinished basement areas are required to have GFCI protection of all 120 volt receptacles including the required 20 ampere circuit for laundry outlets if present.  Since concrete floors are definitely conductive you may want to install a two pole GFCI breaker on the 240 volt circuit. 

As for the likelihood of nuisance tripping of GFCI receptacles that protect the receptacles that are attached to the load terminals of the receptacle it is no worse than the likelihood of nuisance tripping of a GFCI breaker.  All of the principles of operation are the same.  The only difference between the two devices is where they are located.  One is in the box were the first receptacle needing protection is located.  The other is in the electrical panel that supplies that circuit. 

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W3TDH