# Code requirment exposed work grounding etc.



## joedreamliner787 (Sep 27, 2011)

Hi guys,
I got into an argument with another electrician because after looking at his work he did not ground the j-boxes for the exposed work, instead he pig tailed the grounds and went right to the outlets without making an additional pigtail going to the box itself and he argues the EMT serves as a ground and when you screw the duplex ring to the box it's grounded. I said no you have to add a pig tail and ground the box. He said "show me in the code where it states that" Do you guys know exactly where that is? I looked in bonding etc but there is just too much to look at. I'm on the job now and sending this from my phone and I want to prove this guy wrong.


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## 480sparky (Sep 20, 2007)

*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 or nut 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 flush-type boxes.


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## sbrn33 (Mar 15, 2007)

480sparky said:


> *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 or nut locking means and (2) when the cover mounting holes are located on a flat non-raised portion of the cover.
> 
> ...


Learn something new every day. Wonder if the regular ones are listed now.


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## 480sparky (Sep 20, 2007)

sbrn33 said:


> Learn something new every day. Wonder if the regular ones are listed now.


Racos come with a pair of 6-32 screws & nuts.


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## Bbsound (Dec 16, 2011)

Wouldn't the EMT ground the box? A egc is not even required by NEC correct?


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## 480sparky (Sep 20, 2007)

Bbsound said:


> Wouldn't the EMT ground the box? A egc is not even required by NEC correct?


An ECG *is* required. You can use EMT as an EGC, however.


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## electricmanscott (Feb 11, 2010)

Bbsound said:


> Wouldn't the EMT ground the box? A egc is not even required by NEC correct?


This is really about bonding the receptacle to the box or the other way around.


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## don_resqcapt19 (Jul 18, 2010)

If you have installed an EGC of the wire type, it must be bonded to the box. Metal to metal contact or self grounding recepacles cannot be used to bond the EGC of the wire type to the box. Those two methods can only be used for the required bonding of the receptacle.


> *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).


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## electrictim510 (Sep 9, 2008)

... Oops. Didnt read OP right.


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## Bbsound (Dec 16, 2011)

electricmanscott said:


> This is really about bonding the receptacle to the box or the other way around.


Right, my point being that a grounding conductor (in addition to the EMT) is not even required (by NEC in MOST applications), thus the receptacle properly mounted to the box is grounded.


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## Bbsound (Dec 16, 2011)

480sparky said:


> An ECG *is* required. You can use EMT as an EGC, however.


Yes you are correct, I was thinking EMT as a raceway, not as a conductor.


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## electricmanscott (Feb 11, 2010)

Bbsound said:


> Right, my point being that a grounding conductor (in addition to the EMT) is not even required (by NEC in MOST applications), thus the receptacle properly mounted to the box is grounded.


But if there is an EGC it has to connect to the box which isn't the case here. The receptacle must be bonded to the box, how that happens could be a few different ways. Regardless of the method used the EGC itself has to attach to the box.


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## 480sparky (Sep 20, 2007)

Bbsound said:


> Right, my point being that a grounding conductor (in addition to the EMT) is not even required (by NEC in MOST applications), thus the receptacle properly mounted to the box is grounded.



Only if the conditions of 250.146 are met.


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## Bbsound (Dec 16, 2011)

480sparky said:


> Only if the conditions of 250.146 are met.


why I said "properly mounted"


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## McClary’s Electrical (Feb 21, 2009)

It seems only one person(don) read the op closely. This is not about grounding the receptacle like 480 posted. Its about whether the box is required to have the egc bonded to the box. If it is a wire egc then yes, it is required to be bonded to the box. If there is no wire egc, your conduit can be your egc, and THEN the article 480 posted applies to ground the receptacle. But that's not what the op was about anyway.


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## Shockdoc (Mar 4, 2010)

But if the receptacle contact yoke affixes directly to box mount even a standard ( not self grounding) device is acceptable. I cut in about 25 gem boxes and did not pigtail one device, the existing set back boxes got pigtailed..

Does it have to be bonded to box outside of 517 ?


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## McClary’s Electrical (Feb 21, 2009)

Shockdoc said:


> But if the receptacle contact yoke affixes directly to box mount even a standard ( not self grounding) device is acceptable. I cut in about 25 gem boxes and did not pigtail one device, the existing set back boxes got pigtailed..
> 
> Does it have to be bonded to box outside of 517 ?


 Yoke contact is acceptable for grounding the receptacle from an already grounded box but yoke contact is not acceptable to ground a box from an already grounded receptacle


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## joedreamliner787 (Sep 27, 2011)

Wow this post got a lot of hits. Thanks to all first and foremost but if EMT is to serve as the EGC then is the EMT in the panel required to have a ground nut that is bonded to the EGC buss? Now my additional concern is simple, if for some reason a forklift hits a j-box with product (I have seen this happen) and he or she knocks the EMT out of the box connector and there is no EGC ran thru the conduit then that means anything after that point is disconnected and not grounded. Some of the drivers don't even know if they hit something. At least having the EGC wire ran and boned to the box if for some reason the EMT is pulled away from the box connector by a few inches at least everything is most likely still grounded. Now on a surface mount box (exposed work) with a receptacle screw and nut installed to the mulberry duplex cover (top and bottom of receptacle) if the two diagonal cover screw screws are removed and the mulberry pulled away from the box that duplex is no longer grounded. I was taught by a great electrician to run an EGC in the EMT and pig tail the grounds in addition to bonding the box, that electrician is my dad :thumbsup:


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## Bbsound (Dec 16, 2011)

joedreamliner787 said:


> Wow this post got a lot of hits. Thanks to all first and foremost but if EMT is to serve as the EGC then is the EMT in the panel required to have a ground nut that is bonded to the EGC buss? Now my additional concern is simple, if for some reason a forklift hits a j-box with product (I have seen this happen) and he or she knocks the EMT out of the box connector and there is no EGC ran thru the conduit then that means anything after that point is disconnected and not grounded. Some of the drivers don't even know if they hit something. At least having the EGC wire ran and boned to the box if for some reason the EMT is pulled away from the box connector by a few inches at least everything is most likely still grounded. Now on a surface mount box (exposed work) with a receptacle screw and nut installed to the mulberry duplex cover (top and bottom of receptacle) if the two diagonal cover screw screws are removed and the mulberry pulled away from the box that duplex is no longer grounded. I was taught by a great electrician to run an EGC in the EMT and pig tail the grounds in addition to bonding the box, that electrician is my dad :thumbsup:


I always run a grounding wire for a recpt circuit, even in EMT and I have never seen a spec that did not require one. 

We were just answering your question as per the NEC.


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## KGN742003 (Apr 23, 2012)

Wow this post got a lot of hits. Thanks to all first and foremost but if EMT is to serve as the EGC then is the EMT in the panel required to have a ground nut that is bonded to the EGC buss? Not usually, unless some other condition is present. An eccentric knockout and over 250 volts for instance. Now my additional concern is simple, if for some reason a forklift hits a j-box with product (I have seen this happen) and he or she knocks the EMT out of the box connector and there is no EGC ran thru the conduit then that means anything after that point is disconnected and not grounded. Some of the drivers don't even know if they hit something. At least having the EGC wire ran and boned to the box if for some reason the EMT is pulled away from the box connector by a few inches at least everything is most likely still grounded. If the install is subject to physical damage EMT is unacceptable right? Now on a surface mount box (exposed work) with a receptacle screw and nut installed to the mulberry duplex cover (top and bottom of receptacle) if the two diagonal cover screw screws are removed and the mulberry pulled away from the box that duplex is no longer grounded. Why would it need to be grounded in that situation? Surely it can be reasonably assumed that the receptacle won't be in use. I was taught by a great electrician to run an EGC in the EMT and pig tail the grounds in addition to bonding the box, that electrician is my dad :thumbsup: Great advice which certainly won't hurt anything, and may be a better install in some cases.


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## RHWilks (Jul 14, 2012)

For my Evil Purpose, I install a EGC in every conduit.. bond the box and pig tail up to the device. I was doing a remodel in a wood framed apartment building, that was ran in EMT, with out a EGC installed..I found a conduit apart.. grabbed one side and then the other to pull it back together, and got the daylights knocked out of me. There was short down the line that was looking for a path to ground. buildings move.. People don't tighten fittings. EGC is a safety measure in my mind.


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## Magnettica (Jan 23, 2007)

RHWilks said:


> For my Evil Purpose, I install a EGC in every conduit.. bond the box and pig tail up to the device. I was doing a remodel in a wood framed apartment building, that was ran in EMT, with out a EGC installed..I found a conduit apart.. grabbed one side and then the other to pull it back together, and got the daylights knocked out of me. There was short down the line that was looking for a path to ground. buildings move.. People don't tighten fittings. EGC is a safety measure in my mind.




An EGC is a vital component to a solidy grounded electrical system. 



> *Solidly grounded.* This type of grounding system is most commonly used in industrial and commercial power systems, where grounding conductors are connected to earth ground with no intentional added impedance in the circuit. A main secondary circuit breaker is a vital component required in this system, although it has no bearing in other grounding systems. This component is large in size because it has to carry the full load current of the transformer. Back-up generators are frequently used in this type of grounding system in case a fault shuts down a production process. When this happens, the generators become solidly grounded. However, it’s important to note that the generators aren’t designed for the larger short circuit current associated with solidly grounded systems.
> 
> A solidly grounded system has high values of current ranging between 10kA and 20kA. This current flows through grounding wires, building steel, conduit, and water pipes, which can cause major damage to equipment and shut down production processes. When a line-to-ground fault occurs, arcing can create flashes–generally in the terminating box. In this enclosed area, water is turned to steam, causing the terminating box. To locate the fault, all you need to do is follow the smoke.
> 
> ...


http://ecmweb.com/content/basics-grounding-systems


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