bonding metal boxes

[tdawg]

ok if u have a metal raceway ran from a feeder panel to a maybe a 12 by 6 can and ur feeding receptacles or lights from there via mc cable or Emt does that can need to be bonded or grounded. I see people who do and dont . Some say if u make taps in the can yes some say if its a straight pull no . Is ther a definite answer via NEC.

 

[stickboy1375]

By "can" do you mean junction box? and yes it has to be bonded... 250.4(B)(3)

 

[tdawg]

yes junction box

yes junction box

Is the junction box not bonded through the metal Emt .Is that not a code wise good ground path?

 

[stickboy1375]

EMT is an approved grounding means...

 

[Bea]

If using EMT no but if MC is ran to Can it must be bonded to can.

 

[celtic]

...but the jacket of MC is not - unless listed as such. [330.108; 250.118(11)]

 

[tdawg]

does voltage make a difference

does voltage make a difference

whether or not its greater or lesser than 250 volts makes the difference

 

[infinity]

So this is what you have:

Panel feeds junction box with EMT-
From JB to various loads with MC cable.


The box is grounded via the EMT. If over 250 volts and concentric or eccentric KO's are used with the EMT than a bonding jumper is required. The EGC within the MC cables are required to be bonded to the box.

 

[don_resqcapt19]

If there is an EGC in the wiring method it must be connected to the box even where the raceway is an EGC in itself.

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 spliced or joined within the box or to the box with devices suitable for the use in accordance with 250.148(A) through (E).

 

[infinity]

If there is an EGC in the wiring method it must be connected to the box even where the raceway is an EGC in itself.

That is true if the circuit conductors are spliced. If they pass straight through then the EMT is permitted to ground the box.

 

[peter]

I had this situation:
6 3/4" EMT coming into the box
~15~17 MC cables [various 12-2 and 12-3 and 12-4] going out.
All the terminations were at most 3 or 4 wires per wirenut.
Except I had about 22 ground wires to connect.
So I bought a ground bar and used that for all the grounds and simultaneously bonded the box also.

Question?
What if the box is plastic and the pipes metal? What if the box is metal and the pipes plastic?
~Peter

 

[don_resqcapt19]

Peter,

Question?
What if the box is plastic and the pipes metal? What if the box is metal and the pipes plastic?

If the box is plastic, then the conduits that are leaving the box would have to be bonded. If the raceways are nonmetallic and the box is metal it would have to be bonded.
Don

 

[Bea]

If there is an EGC in the wiring method it must be connected to the box even where the raceway is an EGC in itself.

If you have isolated grounds they do not have to be bonded to metal box

 

[don_resqcapt19]

Bea,

If you have isolated grounds they do not have to be bonded to metal box

Yes, per the exception, but the box still has to be bonded to an EGC. That conductor may be the metallic raceway.
Don

 

[mid tenn elect]

a little more clarification, please

a little more clarification, please

I have two circuits, both are 208/240, 3 phase, 4 wire, 60 amps. They both leave the power panel thru 1 1/4" EMT (8 wires total). The first circuit (4 of those wires) will wire nut at a 6" X 6" metal box and feed A/C unit one, where I will provide a bond between the box and the ground wire for circuit one. The second circuit will "pass thru" the first 6" X 6" metal box and, via 3/4" EMT, wire nut in the second 6" X 6" metal box and feed A/C unit two, where I will also provide a bond between box and circuit two's ground. Am I required to cut circuit two's ground wire in box one and ground it in box one, before sending it on to box two ? I read 250.148, and don't belive it requires me to, my business partner thinks otherwise.

 

[LarryFine]

Am I required to cut circuit two's ground wire in box one and ground it in box one, before sending it on to box two ?

Not if box two's conductors are unbroken in box one. With EMT and metal boxes, you don't need to bond either box (barring KO issues) at all, specs aside.

 

[Pierre C Belarge]

KOs in boxes manufactured today are listed as suitable for grounding means and are not required to have additional bonding means, over or under 250 volts.

Take a look at BGUZ for junction boxes and QCIT for outlet boxes.

Also reference 250.97 exception - the first paragraph.

 

[infinity]

Am I required to cut circuit two's ground wire in box one and ground it in box one, before sending it on to box two ? I read 250.148, and don't belive it requires me to, my business partner thinks otherwise.

No as long as the circuit conductors are not spliced and pass through unbroken. If they're spliced within the box than the EGC would be required to be bonded to the box.

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 spliced or joined 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.

 

[tdawg]

grounded or ungrounded system

grounded or ungrounded system

the nec code requirement you are referring to is correct via ungrounded systems not grounded systems

 

[infinity]

the nec code requirement you are referring to is correct via ungrounded systems not grounded systems

Which post are you refering to?