# Grounding Metal Boxes and Outlets - Confused by Something Simple



## ALFisher

Help, please!


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## Ravenworks

I always twist the incoming and outgoing wires together,then pigtail from there to the box and outlet.


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## teamo

Everyone seems to have their own method. On new work I leave the cable that feeds the power to the box extra long. I then twist all of the grounds and lock it all together with a a green wire nut leaving the long one to come through the hole in the wire nut. I wrap the ground screw to bond the box and trim what's left to the correct length, wrapping the end around the green ground lug of the device.


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## ALFisher

Thanks so much for your help. Because neither one of you picked the method someone else told me is acceptable, I am doing it the way I learned how, as it is the closest to what you do and equally safe.


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## J. V.

The answer is none of the above. 
You ground the metal box and the receptacle in each box. Not just at the first one in the circuit.
Like already said. make up all the grounds, neutrals and hots with pigtails for the receptacles. This is when you install the grounding jumper.
I know it's overkill, but it is the right way to do this. :thumbsup:


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## stickboy1375

ALFisher said:


> . When using metal boxes for duplex outlets, are you required to ground to the metal box FIRST before the outlet itself?



When using metal boxes with receptacles the grounding conductor must attach to the box... now we have some options on having to install a grounding jumper from the box to the receptacle or not... 

*250.146 (A) Surface Mounted Box.* Where the box is mounted on the surface, direct metal to metal contact between the device yoke and the box or a contact yoke or a self grounding receptacle shall be permitted to ground the receptacle to the box. 

Basic examples (A) type installation...

















*250.146 (B) Contact Devices or Yokes.* Contact devices or yokes designed and listed as self-grounding shall be permitted in conjunction with the supporting screws to establish the grounding circuit between the device yoke and *flush type boxes*...

What that means is, in option (B) if you buy self grounding receptacles, you don't need a bonding jumper from the receptacle to a* flush* mounted box.

In option (A) If using *SURFACE* mounted boxes, you don't need a bonding jumper if using self grounding receptacles, OR you remove one of the washers on the 6-32 screws on non self grounding receptacles.


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## Jim Port

The incoming and outgoing grounds need to be connected to each other and the box, not by using 2 screws into the box.


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## stickboy1375

Jim Port said:


> The incoming and outgoing grounds need to be connected to each other and the box, not by using 2 screws into the box.


Correct, all grounds entering a box must be physically spliced together.


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## Code05

here ya go. fun reading.

250.148 Continuity and Attachment of Equipment
Grounding Conductors to Boxes. Where circuit conductors
are spliced within a box, or terminated on equipment
within or supported by a box, any equipment grounding conductor(
s) associated with those circuit conductors shall be connected
within the box or to the box with devices suitable for
the use in accordance with 250.148(A) through (E).
Exception: The equipment grounding conductor permitted
in 250.146(D) shall not be required to be connected to the
other equipment grounding conductors or to the box.
(A) Connections. Connections and splices shall be made
in accordance with 110.14(B) except that insulation shall
not be required.
(B) Grounding Continuity. The arrangement of grounding
connections shall be such that the disconnection or the
removal of a receptacle, luminaire, or other device fed from
the box does not interfere with or interrupt the grounding
continuity.
(C) Metal Boxes. A connection shall be made between the
one or more equipment grounding conductors and a metal
box by means of a grounding screw that shall be used for
no other purpose, equipment listed for grounding, or a
listed grounding device.
(D) Nonmetallic Boxes. One or more equipment grounding
conductors brought into a nonmetallic outlet box shall
be arranged such that a connection can be made to any
fitting or device in that box requiring grounding.
(E) Solder. Connections depending solely on solder shall
not be used.


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## Code05

for your added pleasure.

250.146 Connecting Receptacle Grounding Terminal to
Box. An equipment bonding jumper shall be used to connect
the grounding terminal of a grounding-type receptacle
to a grounded box unless grounded as in 250.146(A)
through (D). The equipment bonding jumper shall be sized
in accordance with Table 250.122 based on the rating of the
overcurrent device protecting the circuit conductors.
(A) Surface-Mounted Box. Where the box is mounted on
the surface, direct metal-to-metal contact between the device
yoke and the box or a contact yoke or device that
complies with 250.146(B) shall be permitted to ground the
receptacle to the box. At least one of the insulating washers
shall be removed from receptacles that do not have a contact
yoke or device that complies with 250.146(B) to ensure
direct metal-to-metal contact. This provision shall not apply
to cover-mounted receptacles unless the box and cover
combination are listed as providing satisfactory ground
continuity between the box and the receptacle. A listed
exposed work cover shall be permitted to be the grounding
and bonding means when (1) the device is attached to the
cover with at least two fasteners that are permanent (such
as a rivet) or have a thread locking or screw locking means
and (2) when the cover mounting holes are located on a flat
non-raised portion of the cover.
(B) Contact Devices or Yokes. Contact devices or yokes
designed and listed as self-grounding shall be permitted
in conjunction with the supporting screws to establish
the grounding circuit between the device yoke and flushtype
boxes.
(C) Floor Boxes. Floor boxes designed for and listed as
providing satisfactory ground continuity between the box
and the device shall be permitted.
(D) Isolated Receptacles. Where installed for the reduction
of electrical noise (electromagnetic interference) on the
grounding circuit, a receptacle in which the grounding terminal
is purposely insulated from the receptacle mounting
means shall be permitted. The receptacle grounding terminal
shall be connected to an insulated equipment grounding
conductor run with the circuit conductors. This equipment
grounding conductor shall be permitted to pass through one
or more panelboards without a connection to the panelboard
grounding terminal bar as permitted in 408.40, Exception,
so as to terminate within the same building or
structure directly at an equipment grounding conductor terminal
of the applicable derived system or service. Where
installed in accordance with the provisions of this section,
this equipment grounding conductor shall also be permitted
to pass through boxes, wireways, or other enclosures without
being connected to such enclosures.
FPN: Use of an isolated equipment grounding conductor
does not relieve the requirement for grounding the raceway
system and outlet box.


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## ALFisher

J. V. said:


> The answer is none of the above.
> You ground the metal box and the receptacle in each box. Not just at the first one in the circuit.
> Like already said. make up all the grounds, neutrals and hots with pigtails for the receptacles. This is when you install the grounding jumper.
> I know it's overkill, but it is the right way to do this. :thumbsup:


I realize you ground the metal box and the receptacle in EACH box. My first question was whether the method someone gave to me was correct. Here is the method - connect both the incoming and the outgoing ground to each other - attach those to the receptacle, but not the box, as the receptacle is "connected" to the box via the receptacle's screws.

Based on the responses, the answer to that question is no, that is not correct and should not be done, which is what I believed.

However, now, the latest responses have left me confused again, as it sounds like my method is not correct either. According to the newer responses, I connect the incoming and outgoing to each other and THEN connect to the box and the outlet by pigtail or by leaving the incoming wire longer. Is this correct?


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## stickboy1375

ALFisher said:


> I realize you ground the metal box and the receptacle in EACH box. My first question was whether the method someone gave to me was correct. Here is the method - connect both the incoming and the outgoing ground to each other - attach those to the receptacle, but not the box, as the receptacle is "connected" to the box via the receptacle's screws.
> 
> Based on the responses, the answer to that question is no, that is not correct and should not be done, which is what I believed.
> 
> However, now, the latest responses have left me confused again, as it sounds like my method is not correct either. According to the newer responses, I connect the incoming and outgoing to each other and THEN connect to the box and the outlet by pigtail or by leaving the incoming wire longer. Is this correct?


To keep this real simple and code compliant, splice all your grounds together, add a bonding jumper to the box and device... And you are correct, the DEVICE cannot bond the box, but the box can bond the device if certain requirements are met.


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## Jim Port

It doesn't matter if you leave one long or use a pigtail to the box and/or the device. What matters is that the grounds are connected together and to the box and the device.


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## ALFisher

Got it. Now, reading the code makes more sense too. This site is great. Thanks so much. Now, one day, I learn why (other than the code says so) connecting the two egcs is required rather than connecting both to the box, but I leave that for another day.


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## hammerlane

For basement switch in EMT I grounded the box and the switch.


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## Evstarr

ALFisher said:


> ... Now, one day, I learn why (other than the code says so) connecting the two egcs is required rather than connecting both to the box, but I leave that for another day.


There is supposed to be more secure contact between the conductors if they are twisted together and crimped or nutted than relying on the grounding screw to hold them tight as it may vibrate loose. If the screw loosens or one conductor slipped out from under the screw, continuous ground would be lost. 

Same idea as not double tapping a breaker or Putting two hots on one device screw. 

A conductor may be looped around a screw on its way elsewhere but if it is cut it must be properly terminated.


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## J. V.

hammerlane said:


> For basement switch in EMT I grounded the box and the switch.


The tape around the device makes me laugh. But hey, whatever floats your boat. :laughing:


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## ALFisher

J. V. said:


> The tape around the device makes me laugh. But hey, whatever floats your boat. :laughing:


Why is this funny? I have seen several folks do this in metal boxes.


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## stickboy1375

ALFisher said:


> Why is this funny? I have seen several folks do this in metal boxes.


Yeah, and its funny to come across.


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## rjniles

hammerlane said:


> For basement switch in EMT I grounded the box and the switch.


I do not like using 2 connections under a ground screw, not sure it meets code. I would leave that bare ground long, wrap on the ground screw and continue to the recep.

I only use tape on a receptacle when I install a a GFCI recep. in an old (small) metal box. No reason in the 4" box you have.

I assume you are using the EMT as a sleeve and not running NM all the way.


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## rjniles

Another point to the OP: 

If you run the bare ground to the receptacle and try to use a self grounding receptacle to ground the box, you lose the box ground if you pull out the receptacle. Or down the road if someone changes the self grounding receptacle to a standard non- grounding, you lose the ground to the box.


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## stickboy1375

rjniles said:


> I do not like using 2 connections under a ground screw, not sure it meets code.


It's a violation...


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## stickboy1375

rjniles said:


> Another point to the OP:
> 
> If you run the bare ground to the receptacle and try to use a self grounding receptacle to ground the box, you lose the box ground if you pull out the receptacle. Or down the road if someone changes the self grounding receptacle to a standard non- grounding, you lose the ground to the box.


You can't bond the box via the device, but you can bond the device via the box... What you speak is a code violation so its a moot point.


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## rjniles

stickboy1375 said:


> You can't bond the box via the device, but you can bond the device via the box... What you speak is a code violation so its a moot point.


I was trying to explain the rational behind the code.


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## stickboy1375

rjniles said:


> I was trying to explain the rational behind the code.


Why not just stick to the facts? The box must be bonded....


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## rjniles

stickboy1375 said:


> Why not just stick to the facts? The box must be bonded....


You are getting a little testy


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## stickboy1375

rjniles said:


> You are getting a little testy


Absolutely not... black and white words.... no need to add emotion to that. 

I was trying to keep it simple and clean...


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## hammerlane

rjniles said:


> I only use tape on a receptacle when I install a a GFCI recep. in an old (small) metal box. No reason in the 4" box you have


That piece of tape only cost a nickel.



rjniles said:


> I assume you are using the EMT as a sleeve and not running NM all the way.


EMT is a sleeve for the vertical drop.


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## hammerlane

J. V. said:


> The tape around the device makes me laugh. :laughing:


Glad you are amused. 



J. V. said:


> But hey, whatever floats your boat. :laughing:


I don't know where you fish but water typically floats mine.


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## Bobaker

This is interesting because it seems everyone has an opinion but few facts. If you're mounting metal boxes on wood studs, what is grounding the metal box going to achieve? If metal studs, that's different. 
Researching this pigtail question previously brought up similar lack of knowledge responses. NEC 300.14 refers to pigtails for multi-wire circuits but does not apply to single circuit runs, except California. The device can be used as a means of continuity in the circuit. Even in multi-wire circuits the wire can be looped without pigtailing 14.b. 
If you ground the box make sure the device is labeled self grounding so you don't have to run the ground conductor (wire) to the device (receptacle). Tie the grounds together , use a green ground nut, secure ground wire to box. Done!

Many people miss apply Codes by either not understanding what is being referred to, failing to look at the Code Section heading they are reading from, or applying what they learned on one job that does not apply to other situations, or receiving poor instructions from someone else when they started their trade. I have been an Inspector and have 8 ICC certifications, 7 licenses, plus 40 yrs experience.


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## Desertdrifter

Do you have shiny armor too?


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## stickboy1375

Bobaker said:


> If you're mounting metal boxes on wood studs, what is grounding the metal box going to achieve?
> 
> I have been an Inspector and have 8 ICC certifications, 7 licenses, plus 40 yrs experience.


You should be able to answer your own question then.... :whistling2:

If you don't know why we bond a metal box after 40 years, i'm kind of scared.


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## rjniles

Bobaker said:


> If you ground the box make sure the device is labeled self grounding so you don't have to run the ground conductor (wire) to the device (receptacle). Tie the grounds together , *use a green ground nut*, secure ground wire to box. Done!
> 
> Many people miss apply Codes by either not understanding what is being referred to, failing to look at the Code Section heading they are reading from, or applying what they learned on one job that does not apply to other situations, or receiving poor instructions from someone else when they started their trade. I have been an Inspector and have 8 ICC certifications, 7 licenses, plus 40 yrs experience.


Or any other color wire nut, does not have to be green.

This post is 2 years old.


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## Cletis

Don't forget in 2017 I think you have to bond the nails on your blue carlon boxes as well...


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## Stubbie

> This is interesting because it seems everyone has an opinion but few facts. If you're mounting metal boxes on wood studs, what is grounding the metal box going to achieve? If metal studs, that's different.


 In reply to the first sentence ... BTW... this thread is 2 years old ..  Anyway we posted the relevant NEC code articles, did you not read them? Those are the facts .. :thumbsup: The next sentence/question (underlined) I have no words for other than .. as the saying goes .. there aren't stupid questions just stupid answers .. 

I'd love to hear you explain why wood negates grounding the metal box and if it's attached to metal studs it makes things all different ... :huh: 



> I have been an Inspector and have 8 ICC certifications, 7 licenses, plus 40 yrs experience


.
Which only means that it doesn't matter how much training and education you have or how many licenses you have .. you can still misunderstand the basic fundamentals of bonding metal ' likely to be energized ' with the EGC.


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## Stubbie

I hope he isn't wanting to play the grounding / bonding twist ...


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## jells

Don't want to stir up a hornets nest, but got a question after reading this thread that came up on a search. Is there any reason one can't wrap the incoming ground round the green box grounding screw THEN connect it to the outgoing and device pigtail? Seems to me it's one less pigtail to crowd the box with.


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## Jim Port

One longer grounding conductor can wrap the ground screw and splice to any other grounds and connect to the device. In fact, that is the idea behind the Greenie wire nuts.


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## jells

Jim Port said:


> One longer grounding conductor can wrap the ground screw and splice to any other grounds and connect to the device. In fact, that is the idea behind the Greenie wire nuts.


I guess it's taste, but I'd rather continue to use a 4 hole push in connector with 2 pigtails rather than use that greenie nut.


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## tylernt

jells said:


> Is there any reason one can't wrap the incoming ground round the green box grounding screw THEN connect it to the outgoing and device pigtail? Seems to me it's one less pigtail to crowd the box with.


You can if you have at least 180° of wrap around the screw. I've done it, I like it, it's neat and clean and it has passed inspection. It's called a "rabbit ear". You can even rabbit-ear multiple devices with a continuous super-long ground conductor.

I believe it's also acceptable to rabbit-ear neutral and hot conductors, but it's a pain to strip off a little chunk of insulation from the middle of a wire.


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## jells

tylernt said:


> You can if you have at least 180° of wrap around the screw. I've done it, I like it, it's neat and clean and it has passed inspection. It's called a "rabbit ear". You can even rabbit-ear multiple devices with a continuous super-long ground conductor.
> 
> I believe it's also acceptable to rabbit-ear neutral and hot conductors, but it's a pain to strip off a little chunk of insulation from the middle of a wire.


Thanks for the confirmation. Yeah, it would have to be extraordinary circumstances to do it for a hot or neutral. 

I gotta say, "passed inspection" means little to me since I discovered in a 10 year old subpanel that passed that the neutral was bonded and multicircuit breakers were on the same leg. At least around here there's a "hand wave pass" when the inspector & electrician are of long acquaintance.


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## tylernt

jells said:


> I gotta say, "passed inspection" means little to me ... there's a "hand wave pass" when the inspector & electrician are of long acquaintance.


Agreed. I'm a "clueless homeowner" rather than an "experienced electrician" though, so I feel I get a little more scrutiny. In this case the inspector definitely looked in my JB.


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