EMT connector grounding?

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Kyle1974

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I am in the process of wiring a small buisness and don't understand the requierments for grounding EMT connectors at pull boxes, service pannels, and switch/rec. boxes. I understand that it is needed for the switch and rec boxes but junction/pull boxes?:-? and if so where can I get the grounding connectors? :-? Sorry for all the question but I am trying to get this right the first time. Thanks for any info you can offer Kyle.
 
Kyle1974 said:
I am in the process of wiring a small buisness and don't understand the requierments for grounding EMT connectors at pull boxes, service pannels, and switch/rec. boxes. I understand that it is needed for the switch and rec boxes but junction/pull boxes?:-? and if so where can I get the grounding connectors? :-? Sorry for all the question but I am trying to get this right the first time. Thanks for any info you can offer Kyle.
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First off. Do you own a copy of the currently adopted NEC for your area?
 
Kyle1974 said:
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but junction/pull boxes?:-? and if so where can I get the grounding connectors? :-?
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In the sense of a junction box it can be as small as (or smaller) than a 4" sq box.
If theres not a ground screw attachment hole in the box then you drill and tap a hole or drill for a bolt/nut & use proper size lug for the junction box, determined per the largest ground wire that enters the junction box, and that size should run home to point of service.
It might just be 12 and 14 AWG's Use 12 to box and continue to PoS home.
If 12's and 8's then use 8 in junction box ground(bonded) and continue to PoS home.
 
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Unless I'm mistaken, if there are no splices in the box, direct grounding is not required.
 
LarryFine said:
Unless I'm mistaken, if there are no splices in the box, direct grounding is not required.
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Why would I have to directly ground a splice box. If I have emt going into a 4 inch square box isn't the box grounded??? What does a splice have to do with the scenario?
 
Dennis, read 250.148.

FWIW, here is the NECH commentary;

Where a metal box is used in a metal raceway system and there is a wire-type equipment grounding conductor installed in the raceway, it is not required that the wire-type equipment grounding conductor be connected to the pull box, provided the box is effectively grounded by the metal raceway and the circuit conductors are not spliced or terminated to equipment in the metal box. An example of this provision would be where conductors are run unbroken through a pull box.
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Roger
 
roger said:
Dennis, read 250.148.

FWIW, here is the NECH commentary;

Roger
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Thanks Roger -- I have always grounded the boxes even with no splice but I didn't realize I had to with a splice.
 
I have the 2005 NEC book and will receive refresher training and receive my 2008 copy in August. So if I am reading this right only if there is a slice in the box I have to ground it? Someone had told me that each EMT connector had to have a bonding jumper to the box it connects is this true? Which section in the NEC book can I reference this?
 
I am sorry this is still bothering me. If the metal raceway is sufficient as a ground then the box is effectively grounded. If we don't pull an egc then we are fine however if we pull an egc we must ground the box if there is a splice. Odd.......

Also I am not quite sure about the commentary

Where a metal box is used in a metal raceway system and there is a wire-type equipment grounding conductor installed in the raceway, it is not required that the wire-type equipment grounding conductor be connected to the pull box, provided the box is effectively grounded by the metal raceway and the circuit conductors are not spliced or terminated to equipment in the metal box. An example of this provision would be where conductors are run unbroken through a pull box.
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The purple text, IMO, is saying that if the conductors are not splice to equip. in the box or not terminated to equip. in the box. The following sentence says an example is......Thus there must be other examples--- not sure what they are other than a splice without equipment in the box.
 
Dennis Alwon said:
I am sorry this is still bothering me. If the metal raceway is sufficient as a ground then the box is effectively grounded. If we don't pull an egc then we are fine however if we pull an egc we must ground the box if there is a splice. Odd.......equipment in the box.
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It used to be that if you pulled a wire EGC you had to bond it to the box splices or not.

Then it was changed so that if it was just a pulling point (the same as an LB for example) you would not have to bond it.
 
iwire said:
It used to be that if you pulled a wire EGC you had to bond it to the box splices or not.

Then it was changed so that if it was just a pulling point (the same as an LB for example) you would not have to bond it.
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But why? If the box is already bonding with the emt and an egc is not required then why require a redundant ground?
 
Dennis I would guess it is because the more paths back the lower the impedance will be .
 
Dennis Alwon said:
But why? If the box is already bonding with the emt and an egc is not required then why require a redundant ground?
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Why not?

If I run a single 12 AWG 20 amp two wire circuit in EMT can I install a 14 AWG green in addition to the EMT?
 
iwire said:
Why not?

If I run a single 12 AWG 20 amp two wire circuit in EMT can I install a 14 AWG green in addition to the EMT?
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I don't have a problem with doing it but I don't understand the requirement. Why not is not a good answer. I am asking why the nec would require a redundant ground only if it is available.
 
Dennis Alwon said:
I am asking why the nec would require a redundant ground only if it is available.
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So that it doesn't appear as though we're wasting material. :roll: :grin:

Roger
 
Kyle1974 said:
I have the 2005 NEC book and will receive refresher training and receive my 2008 copy in August. So if I am reading this right only if there is a slice in the box I have to ground it?
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If the conductors are spliced or if they are connected to a device or piece of equipment in or supported by the box.

Kyle1974 said:
Someone had told me that each EMT connector had to have a bonding jumper to the box it connects is this true?
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No, this is false.

Kyle1974 said:
Which section in the NEC book can I reference this?
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250.148, this article section is the same in 2005 and 2008.

Roger
 
The 2008 NEC clarifies that the EMT itself will serve as the conductive path and is an equipment grounding conductor. As pointed out, tighten the fittings and you are done.
However, if you choose to pull a wire type equipment grounding conductor, you are allowed to pull thru a box with out bonding to the box, if there are no splices or devices in the box. If there are, then you bond to that box. This rule was added in the 2005 NEC.
 
splices in box

splices in box

I WILL BE RUNNING 1/2" emt in a warehouse for 10 lights i will use a egc so every junction must be bonded to the ecg if it has splices in ti. if i don't use egc i would bond the egc from the light to the box it inters?
 
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