Gounding And Bonding Emt Question

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Phil Devine

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Article 250.118 (4) states that the equipment grounding conductor run with or enclosing the circuit conductor shall be one or more of the following: "Electrical metallic tubing with an additional equipment gromnding conductor." we have an installation where EMT was used throughout the school with a separate equipment grounding conductor. This poses the following questiosn:

How do we interpet Article 250.148? Does each pull box where the conductors are spliced require the box to be bonded to the equipment grounding conductors throughout the conduit run?

Does this mean that even when there are no devices, the box must be bonded to the equipment grounding conductor when the conductors are spliced?
 
Phil Devine said:
Article 250.118 (4) states that the equipment grounding conductor run with or enclosing the circuit conductor shall be one or more of the following: "Electrical metallic tubing with an additional equipment gromnding conductor." we have an installation where EMT was used throughout the school with a separate equipment grounding conductor. This poses the following questiosn:

How do we interpet Article 250.148? Does each pull box where the conductors are spliced require the box to be bonded to the equipment grounding conductors throughout the conduit run?

Does this mean that even when there are no devices, the box must be bonded to the equipment grounding conductor when the conductors are spliced?
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Yes, every box must be bonded if there is a grounding wire present.
 
electricguy61 said:
Yes, every box must be bonded if there is a grounding wire present.
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No, not any longer.

If the box is really just a pull box without devices or terminations the EGC does not have to be bonded to the box.
 
iwire said:
No, not any longer.

If the box is really just a pull box without devices or terminations the EGC does not have to be bonded to the box.
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The explanation in my 2005 handbook says""not spliced or terminated. An example of this provision would be where conductors are run unbroken through a pull box." If there's a wire nut on the grounds, the box must be bonded to the grounding wire. (I believe) The OP asked about a splice box.
 
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electricguy61 said:
The explanation in my 2005 handbook says""not spliced or terminated. An example of this provision would be where conductors are run unbroken through a pull box." If there's a wire nut on the grounds, the box must be bonded to the grounding wire. (I believe) The OP asked about a splice box.
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Correct, if the EGC is spliced within the box or terminated on a device in the box the EGC must also be bonded to the box. If this is just a pull box and the conductors pass through the box without a splice then you are not required to bond the EGC to the box.

Chris
 
The 2008 Handbook states the same thing, that if the wires are unbroken and pulled through, then they do not have to be bonded to the box. What is unclear is when the boxes have splices (with or without devices) then is it necessary?

If the purpose of the grounding conductor is to return a ground fault current and since the EMT by itself can not be used, shouldn't it be bonded to ground at every point possible to between conduit joints and connections for continuity and to ensure it can not be energized?
 
Phil Devine said:
and since the EMT by itself can not be used,
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The NEC allows the use of EMT 'alone' (and many raceway types) to serve as the EGC.

250.118 spells it out, but now I am going in a circle again.
 
electricguy61 said:
If there is a splice in the grounding conductor, there must be a bond as well. No splice, no bond.
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I disagree just a little bit. 250.148 says "Where circuit conductors are spliced...." The splice doesn't have to be in the grounding conductor in order to require the bonding to the box. A splice in any of the circuit conductors would trigger the bonding requirement.
 
eprice said:
I disagree just a little bit. 250.148 says "Where circuit conductors are spliced...." The splice doesn't have to be in the grounding conductor in order to require the bonding to the box. A splice in any of the circuit conductors would trigger the bonding requirement.
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I agree. :)
 
Article 250.118 (4) states that the equipment grounding conductor run with or enclosing the circuit conductor shall be one or more of the following:

"Electrical metallic tubing with an additional equipment grounding conductor."

I don't believe there is an option anymore to just use EMT itseld as the EGC. Therefore, should the conduit be bonded to the separate EGC at each pull or junction box? How do we find out for sure what the code implies?
 
Phil Devine said:
Article 250.118 (4) states that the equipment grounding conductor run with or enclosing the circuit conductor shall be one or more of the following:

"Electrical metallic tubing with an additional equipment grounding conductor."

I don't believe there is an option anymore to just use EMT itseld as the EGC. Therefore, should the conduit be bonded to the separate EGC at each pull or junction box? How do we find out for sure what the code implies?
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Which edition of the NEC are you quoting from?

My 2008 NEC has no such wording.

Here is a direct copy of what my 2008 NEC section 250.188 says.

250.118 Types of Equipment Grounding Conductors.
The equipment grounding conductor run with or enclosing the circuit conductors shall be one or more or a combination of the following:
FPN: For effective ground-fault current path, see 250.2 Definition.
(1) A copper, aluminum, or copper-clad aluminum conductor. This conductor shall be solid or stranded; insulated, covered, or bare; and in the form of a wire or a busbar of any shape.
(2) Rigid metal conduit.
(3) Intermediate metal conduit.
(4) Electrical metallic tubing.
(5) Listed flexible metal conduit meeting all the following conditions:
a. The conduit is terminated in listed fittings.
b. The circuit conductors contained in the conduit are protected by overcurrent devices rated at 20 amperes or less.
c. The combined length of flexible metal conduit and flexible metallic tubing and liquidtight flexible metal conduit in the same ground return path does not exceed 1.8 m (6 ft).
d. Where used to connect equipment where flexibility is necessary after installation, an equipment grounding conductor shall be installed.
(6) Listed liquidtight flexible metal conduit meeting all the following conditions:
a. The conduit is terminated in listed fittings.
b. For metric designators 12 through 16 (trade sizes through ?), the circuit conductors contained in the conduit are protected by overcurrent devices rated at 20 amperes or less.
c. For metric designators 21 through 35 (trade sizes ? through 1?), the circuit conductors contained in the conduit are protected by overcurrent devices rated not more than 60 amperes and there is no flexible metal conduit, flexible metallic tubing, or liquidtight flexible metal conduit in trade sizes metric designators 12 through 16 (trade sizes through ?) in the grounding path.
d. The combined length of flexible metal conduit and flexible metallic tubing and liquidtight flexible metal conduit in the same ground return path does not exceed 1.8 m (6 ft).
e. Where used to connect equipment where flexibility is necessary after installation, an equipment grounding conductor shall be installed.
(7) Flexible metallic tubing where the tubing is terminated in listed fittings and meeting the following conditions:
a. The circuit conductors contained in the tubing are protected by overcurrent devices rated at 20 amperes or less.
b. The combined length of flexible metal conduit and flexible metallic tubing and liquidtight flexible metal conduit in the same ground return path does not exceed 1.8 m (6 ft).
(8) Armor of Type AC cable as provided in 320.108.
(9) The copper sheath of mineral-insulated, metal-sheathed cable.
(10) Type MC cable where listed and identified for grounding in accordance with the following:
a. The combined metallic sheath and grounding conductor of interlocked metal tape?type MC cable
b. The metallic sheath or the combined metallic sheath and grounding conductors of the smooth or corrugated tube-type MC cable
(11) Cable trays as permitted in 392.3 and 392.7.
(12) Cablebus framework as permitted in 370.3.
(13) Other listed electrically continuous metal raceways and listed auxiliary gutters.
(14) Surface metal raceways listed for grounding.
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Chris
 
Phil Devine said:
Article 250.118 (4) states that the equipment grounding conductor run with or enclosing the circuit conductor shall be one or more of the following:

"Electrical metallic tubing with an additional equipment grounding conductor."
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Phil I do not think any NEC edition has that wording, are you working from a locally amended NEC?
 
Phil Devine said:
"Electrical metallic tubing with an additional equipment grounding conductor."
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I can't find that wording in my 2005 or 2008 NEC. Mine just says "Electrical metallic tubing." Is that as amendment by the jurisdiction?
 
eprice said:
I disagree just a little bit. 250.148 says "Where circuit conductors are spliced...." The splice doesn't have to be in the grounding conductor in order to require the bonding to the box. A splice in any of the circuit conductors would trigger the bonding requirement.
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So if the EGC's were spliced, but the circuit conductors were not, no connection to the box would be required.
 
infinity said:
So if the EGC's were spliced, but the circuit conductors were not, no connection to the box would be required.
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Hmmm interesting point. The way the section is worded, I think that is what it actually says. It depends upon whether or not the EGC is considered to be a circuit conductor. There is no definition in the NEC for "circuit conductor".
 
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