# Bonding Jumper in 4 square boxes



## Dizzykidd (Aug 3, 2016)

So my question is "is it required to put a bonding jumper in every 4 square box" I'm confused about this because I was taught you had to do that even if you just used the box as a pull box and no splices were made, you had to cut the ground and bond it. Now that made sense until I learned 358.60 that EMT can be used as an equipment grounding conductor. And 250.96 says enclosures shall be bonded where necessary. So to me it seems like as long as the 4 square is connected to EMT that counts as it being bonded. Please let me know if I'm wrong grounding isn't one of my strongest subjects but that's why I'm trying to learn more.


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## backstay (Feb 3, 2011)

I only bond if the box has a power outlet(switch, receptacle or light and using no concentric knockouts.


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## teufelhounden91 (Jul 8, 2012)

In 250.96(A) it says "any RACEWAY...that are to serve as an EGC shall be bonded WHERE NECESSARY to ensure electrical continuity...in the event of a fault"

In other words if you are using EMT as your equipment grounding conductor then I believe the intent of the code is that you check continuity from one into the other and make sure that EMT is continuous. In the event that one of your connectors or couplings is not tightly fastened you may not have continuity all the way in which case not only is everything not bonded but your EGC is no longer an EGC.

In my opinion it's always a good idea to pull a ground wire in. Then you don't have to worry about this. Great question though.


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## Bird dog (Oct 27, 2015)

Somewhere does it say if the voltage is over 250v to ground the box has to be bonded with grounding conductor? That may have been an engineering spec.


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## teufelhounden91 (Jul 8, 2012)

Also 250.148(C) says any metal box needs to be attached to an EGC by "equipment listed for grounding" - EMT is a listed grounding conductor as per 358.60.

The real answer to this is no. If you're using EMT you can get away with not using a bonding jumper...but it's not as reliable of a method IMO. Conduits can come loose and you really need to ensure continuity before trusting it as an EGC. A ground wire in a box isn't going anywhere unless somebody puts real effort behind it 


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## PlugsAndLights (Jan 19, 2016)

Sometimes it's hard NOT to do something even when there's no good reason
to do it. 
P&L


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## MXer774 (Sep 1, 2014)

Is it required? We all know that EMT is permissible to be used as a grounding conductor.

However, the specs for the job could make it a requirement as well as local AHJ's.

Every city around here requires bonding stingers in the 4 square boxes. 

What really gives me a good laugh, I see them being installed on the new hip lighting control systems where a single RJ45 terminates to the room controller switch. No line voltage present in the device box. :hammer:


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## active1 (Dec 29, 2009)

Every once in a while you open a communication box with an unused ground pigtail, what were they thinking. Maybe it was just prefabed and left that way.

A similar question would come up with pull cans with larger conductors.
I never did unless requested IF the EG was not already spliced.
If requested by whoever a lay-in lug was the way.
Yes it's possible a conduit could come apart. 
But if the feed and load side of the raceway are bonded with a EG conductor that runs thru the raceway it would still be bonded on both sides of the raceway.
It would take multiple bad conduit breaks or high resistance connections to leave the can ungrounded.

With grounding bushings while they may or may not be required by code, if requested and used further reduces loss of EG. Of course it depends if used on every connector and where the breaks are.

For splicing many EGs in can / gutters I would always go with a ground bar, with machine screws, and paint removed. Too Often I see wirenut madness without even connecting the can.

For 4sq boxes out here it's bad in some places here. They get by inspection not bonding the 4sq, using MC cables. For service work it's just 1 more thing I can count on doing (splicing in a EG pigtail) in some places.


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## teufelhounden91 (Jul 8, 2012)

Bird dog said:


> Somewhere does it say if the voltage is over 250v to ground the box has to be bonded with grounding conductor? That may have been an engineering spec.



Are you referring to this?

250.97 Bonding for Over 250 Volts.

For circuits of over 250 volts to ground, the electrical continuity of metal raceways and cables with metal sheaths that contain any conductor other than service conductors shall be ensured by one or more of the methods specified for services in 250.92(B), except for (B)(1).

Exception: Where oversized, concentric, or eccentric knockouts are not encountered, or where a box or enclosure with concentric or eccentric knockouts is listed to provide a reliable bonding connection, the following methods shall be permitted:

250.97(1)
Threadless couplings and connectors for cables with metal sheaths

250.97(2)
Two locknuts, on rigid metal conduit or intermediate metal conduit, one inside and one outside of boxes and cabinets

250.97(3)
Fittings with shoulders that seat firmly against the box or cabinet, such as electrical metallic tubing connectors, flexible metal conduit connectors, and cable connectors, with one locknut on the inside of boxes and cabinets

250.97(4)
Listed fittings


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## Bird dog (Oct 27, 2015)

teufelhounden91 said:


> Are you referring to this?
> 
> 250.97 Bonding for Over 250 Volts.
> 
> ...


Yes, Thank you.


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## TGGT (Oct 28, 2012)

If you're pulling straight through don't bother.

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## Dennis Alwon (May 9, 2009)

Is this what you are looking for



> 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(
> ...


.


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## cabletie (Feb 12, 2011)

It used to be required to "maintain continuity" with the available equipment grounds at each junction box. So conduit ground and wire ground went together at each box. 

About ten years ago they changed the wording so you only need to ground the box with the wire ground (maintain continuity) when a splice is made in the box. 

It was very common to skin back the ground and bug it to the box on feeder pull boxes, even without a splice on the feeders. I never see anybody do that anymore. We always pulled a loop in the ground wire for 4" squares, and grounded the box. Now it's only done when there is a splice or device in the box. 

250.148 Continuity and Attachment of Equipment Grounding Conductors to 
Boxes.
If circuit conductors are spliced within a box or terminated on equipment within or supported by a box, all equipment grounding conductor(s) associated with any of those circuit conductors shall be connected within the box or to the box with devices suitable for the use in accordance with 250.8 and 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.


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## cabletie (Feb 12, 2011)

Damit Dennis, 

I saw this post this morning and didn't have time to respond. I finally get to it and you beat me by a few minutes.:laughing:


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## Dennis Alwon (May 9, 2009)

cabletie said:


> Damit Dennis,
> 
> I saw this post this morning and didn't have time to respond. I finally get to it and you beat me by a few minutes.:laughing:


I can delete my post if it will make you feel better.


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## cabletie (Feb 12, 2011)

No, that's ok. Next time I'll have to eat my sandwich with one hand and type with the other. It's a real Pain trying to copy/paste with a phone while eating.


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## cabletie (Feb 12, 2011)

Hey....now that the question has been answered, can we hijack the thread and make it about deleted posts. :jester::laughing:


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