# Metal boxes with Romex



## ddsrph (Nov 23, 2013)

I have done a little wiring always using romex and plastic or fiberglass boxes. If I use metal boxes with romex and romex connectors do I have to ground the metal boxes to the romex ground with a wire lead or is the box automatically grounded by the receptacle or switch?

Thanks
JM


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## garlicbreath (Jun 25, 2012)

Ground them.

Sent from my Motorola MicroTAC 9800X


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## Stubbie (Jan 7, 2007)

ddsrph said:


> I have done a little wiring always using romex and plastic or fiberglass boxes. If I use metal boxes with romex and romex connectors do I have to ground the metal boxes to the romex ground with a wire lead or is the box automatically grounded by the receptacle or switch?
> 
> Thanks
> JM


You always connect the egc (equipment ground wire) of the romex to the box. If the receptacle or switch is the self grounding type and you use it in a proper metal box you would not be required to connect it, via the green screw on the metal yoke, to the egc of the romex. 

If this is unfinished walls like in a basement and the switch or receptacle mounts to a metal cover with surface mounted metal box and/or your dropping down from joist height to the switch/receptacle locations let us know. Some other requirements take effect in these situations.


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## Anti-wingnut (Oct 18, 2009)

Most adopted codes require switches the receptacles to be hard grounded with wire


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## Stubbie (Jan 7, 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.​* (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.​ Informational Note: Use of an isolated equipment grounding​ conductor does not relieve the requirement for grounding​ the raceway system and outlet box.


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## Stubbie (Jan 7, 2007)

I just noticed in my first reply that I mistakenly identified switches as self grounding. Switches when mounted in metal device boxes are considered effectively grounded by the yoke to box contact and using two 6-32 mounting screws.*
(B) Grounding.​* Snap switches, including dimmer and​
similar control switches, shall be connected to an equipment​ grounding conductor and shall provide a means to​ connect metal faceplates to the equipment grounding conductor,​ whether or not a metal faceplate is installed. Snap​ switches shall be considered to be part of an effective​ ground-fault current path if either of the following conditions​ is met:​ (1) The switch is mounted with metal screws to a metal​ box or metal cover that is connected to an equipment​ grounding conductor or to a nonmetallic box with integral​ means for connecting to an equipment grounding​ conductor.​ (2) An equipment grounding conductor or equipment​ bonding jumper is connected to an equipment grounding​termination of the snap switch.


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## Anti-wingnut (Oct 18, 2009)

Stubbie said:


> I just noticed in my first reply that I mistakenly identified switches as self grounding. Switches when mounted in metal device boxes are considered effectively grounded by the yoke to box contact and using two 6-32 mounting screws.


Some areas are requiring a jumper wire as an amendment to the locality accepted code


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## TimPa (Aug 15, 2010)

did not know about self grounding devices - thanks will watch for that.

suspect that they specify surface mounted boxes because those stud mounted behind drywall, flush mount (?) do not always allow a standard device strap to physically contact a metal box, if the box is installed too deep in the wall. the screw does not then qualify as a connection as far as I know.


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## ddsrph (Nov 23, 2013)

Thanks to all for the replies. Would I be safe to just run the ground wire in all cases? The block house will have only receptacles on the walls that contact the block. All switches and most receptacles will be on interior walls and I may just use fiberglass boxes here. I want to use the narrow depth metal on perimeter walls due to unconventional framing on these walls. Would it also be advisable to use ground fault breakers on the perimeter wall receptacles instead of trying to use ground fault receptacles? It will only take two circuits to cover all the receptacles required on perimeter walls.On the interior walls I would use GFI receptacles, with one serving several standard ones.

Thanks
JM


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## Stubbie (Jan 7, 2007)

Connecting the egc of the romex to the receptacle or switch green grounding screw would be acceptable in all situations but you *must *always include a connection to the metal box.

The NEC states the minimum safety standards for electrical installations.


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