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No splice made. Does metal j-box need to be grounded

23K views 54 replies 17 participants last post by  Minus08 
#1 · (Edited)
Going to install a ceiling hung garage heater. Will be hung very close to the load center which is in garage.

Using a surface mounted j-box to transition from 10-2 NM cable to greenfield.

Going to strip sheating off of about 5 foot of NM cable once it enters j-box before running individual conductors into greenfield.

So is there a need to ground the j-box at this time since no splice is being made?

Thanks
 

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#4 ·
It does not matter. It is a metal box, the NEC requires that it be grounded to the incoming ground from the panel.

If you want to just leave the grounds tied together without attaching to the metal junction box that is your choice. Lets hope no one decides to touch the box while standing in a puddle of water on the garage floor.
 
#14 ·
A few things:

1) Any metal raceway system MUST be bonded!
2) You do not have to cut your ground wire to do this. Simply loop your bare conductor around a green screw in the metal box, and you're good to go!

3) Some folks would argue that the individual conductors from within a non-metallic sheathed cable are not listed for use within other raceway systems. But romex cable is allowed to be sleeved inside of EMT for physical protection. I personally don't believe that sleeving it inside of greenfield or other conduit will cause anything to "burn down" however. Metal flex is more protection than plastic sheathing any day.
 
#19 ·
YES, you certainly DO need to ground the box. ALL metallic boxes MUST be grounded. Want the code section?

Yes, it is non-complaint to strip off part of the sheathing to do what you propose.
Yes, it is still done all the time for short sections of a few feet or less. (I never said that)
 
#20 ·
...Yes, it is still done all the time for short sections of a few feet or less. (I never said that)
Exactly. While a technical violation may exist, it really is not hazardous. The rule that allows for NM cable to be sleeved in conduit requires the sheathing to remain until it enters the final outlet box.
 
#21 ·
gregzoll said:
I understand what you are talking about, but I do not think that you know what you are talking about what you are wanting to do. Here is a clue, Greenfield is no longer used. MC or Metal Conduit is what is used now. It contains a Ground, Neutral and Hot. Even if Greenfield was in use, it would have a Neutral & Hot, with the outer jacket having a bonding strip in it still for ground. How did you plan on pulling five feet of wires from a romex, which is illegal to begin with, inside of something that already has wires inside? So again, suggest that you have a licensed electrician do the work, due to you seem to not understand how to properly wire this.
Greenfield is empty flexible metallic conduit... BX has wire in it and is no longer used at least most places. If it's legal to use nm cable (romex) where you are then do it but leave a loop of wire in that j box in case you need to tap it later and loop the ground around a ground screw without cutting it.
 
#22 ·
Evstarr said:
Greenfield is empty flexible metallic conduit... BX has wire in it and is no longer used at least most places. If it's legal to use nm cable (romex) where you are then do it but leave a loop of wire in that j box in case you need to tap it later and loop the ground around a ground screw without cutting it.
May want to go back and look that term up. Greenfield is the original term for BX. That is where it came from. Flexcon is what the empty metal corrigated is, without any wiring inside.

Two totally different creatures.
 
#25 ·
Kleenex, Xerox, Q-tips, Greenfield. :wink:

Armored cable (AC) was first listed in 1899 for the Sprague Electric Co. of New York, and was originally called “Greenfield Flexible Steel-Armored Conductors,” after one of its inventors, Harry Greenfield. There were originally two experimental versions of this product, one called “AX” and the other “BX,” with the “X” standing for “experimental.” The “BX” version became the one that eventually got produced, and hence the name “BX” stuck, which also became the registered trade name of armored cable for General Electric, who later acquired Sprague Electric. Armored Cable first appeared in the NEC in 1903. (Source Underwriters Laboratories).
 
#26 ·
gregzoll said:
May want to go back and look that term up. Greenfield is the original term for BX. That is where it came from. Flexcon is what the empty metal corrigated is, without any wiring inside.

Two totally different creatures.
I don't believe that's correct greenfield were the inventors but they never called it bx. Bx got it's name cuz it was invented in da bronx
 
#31 ·
Im guessing they want you to sleeve the gf over the wire up into the ceiling and strap the gf to the rafter before it drops through the ceiling.
Sounds kind of hacked to me id go with the 4sq box idea myself,but what do I know? :laughing:
 
#34 ·
I personally see no problem running the bare ground wire in the gf,its same as pulling ground wire through conduit in my book anyway.
Just bond it with a ground screw in the junction box and the heater :)
I would get a couple more screws to hold that junction box though :)
 
#37 ·
I would get a couple more screws to hold that junction box though :)
Thats not the final set up...I have lots of drywall scraps so I just shot a piece into my workbench, popped a hole in it and attached the j-box(with 1 screw) just to show what I want to do.

Figured a picture is worth a thousand words.

didnt think someone would think the photo was my final answer:laughing:
 
#38 ·
I can't really add much to the options but being a little overboard on appearance I would use a 'lay in' grounding lug instead of the wrap around method.
I'm not actually sure that a connection to the box is necessary if the fmc is less than 6 feet in length it would bond the box back to the heater terminal box where the bare equipment ground of the nm would terminate.

I think it would give me more piece of mind to catch the box though.
 
#42 ·
For the difference in cost and ease of finding the ground screw it is probably easier to use the screw. Those lugs are nice in a trough tho or to bond multiple panels.
 
#44 ·
I do not agree regarding grounding the wires or cable that only passes through the box requiring the grounding jumper. It is only required to use the ground pig tail when a device is located at the box or it is the very last box in the run. See articles 408.40 and 250.148. As long as the cable or wire is intact as it passes through, there is no code requiring you to cut, strip and make this connection. The only time this is required is if the box contains a device, the cable or wire is not intact and it is the last box in the run with a receptacle or other device. We do not interupt wire runs in pull boxes. If connections are made in the box, then the ground jumper may be required.

As for the NM (Romex) entering the back of the box. As long as you use a connector, the NM cable can pass through the drywall. This is also true for block walls, brick walls or any other type of wall. As long as the NM cable is not subject to physical damage you can install it most anywhere that is dry. See article 334.

I am also in agreement that the term "Greenfield" is just a brand name, and it's true definition is FMC. (flexible metallic conduit) I still call it Greenfield and if you ask for Greenfield at the supply house you get FMC. See article 348.
 
#45 ·
I am also in agreement that the term "Greenfield" is just a brand name, and it's true definition is FMC. (flexible metallic conduit) I still call it Greenfield and if you ask for Greenfield at the supply house you get FMC. See article 348.
I agree with the box bonding also, plus it may get grounded from the heater.

Didja see post #25? The name certainly has been passed around throughout the years but I found the history interesting.
 
#48 · (Edited)
OK...we did the install before the New England/Balt game and had a couple beers AFTERWARDS.

-new breaker installed
-drywall cut in joist cavity next to panel
-joist drilled to run 10-2 romex from breaker to the hole in drywall
-hole drilled in 3/4" piece birch plywood then installed over hole in drywall
-rear knockout punchout out in j-box
-cable clamp intalled
-romex pulled into j-box, secured with clamp,
-j-box secured to plywood
-greenfield connectors install on j-box and heater
-romex from j-box looped once in j-box and sleaved thru greenfield
-connections made at heater
-breaker on
-heat on
-beer open
-Baltimore Ravens lose....good day.


Thanks for all advice here and yes I know we still need the 4" square cover. Also we left the sheathing on the romex in the j-box.
 
#49 ·
I also enjoyed the game, and am still working on the beer. The only thing I would have done different is the plywood backboard and the box would have been up higher, out of the way. The backboard was unnecessary. I would have mounted the box to a stud for appearance sake. But it looks safe and compliant. :thumbsup:
 
#55 ·
I would rotate the box so the flex feeds from the top.
JB:
that was the idea when we first planned it but then after hanging the heater and seeing how far down the heater hung, feeding the GF from top of box would of required kind of making an "S" to route GF into heater. With leaving the sheathing on romex inside GF, I think the GF would of really looked rough then. But initially the top feed out of the box was the idea.
 
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