GEC in Trough/Gutter

[JasonCo]

Just wanted to shoot a quick question before work tomorrow. So I have a service lateral coming into a Trough. Here it taps into separately housed meters and service disconnects. Each meter enclosure is separately nippled from the gutter. Unfortunately the bottom knockouts of my meter enclosures are 2" and my nipples are 1.25". So I had to use reducers. I understand that in my service equipment one side of the nipple must be bonded per code anyways, so I'm just going to do the meter side b/c of the KO/reducers. Is it okay to daisy chain my bonding jumpers? So basically I have my neutral bonded to the gutter, and a GEC is sent to Earth. I'll then have ONE bonding jumper that goes through nipple one (meter 1), hits the bonding bushing. Then it goes back through the same nipple, then through nipple 2 (meter 2), bonds with bonding bushing and then daisy chains to the other meters using this method. Is this okay to do? I don't see why not, but maybe I'm missing a code or something, just want to make sure.

 

[texie]

There is an easier way to do this. Since the meters have a bonded neutral and the wireway is bonded to neutral you only need to bond one end of the 1.25 nipple. Use a clean punched hole on the wireway with a sealing locknut on the outside and a grounding locknut on the inside. This will comply with 250.92 and avoid needing bonding bushings and jumpers. This will save you a lot of work and material cost.

 

[tom baker]

Yes you can daisy chain, size of bonding jumper is based on largest ungrounded conductor

 

[JasonCo]

There is an easier way to do this. Since the meters have a bonded neutral and the wireway is bonded to neutral you only need to bond one end of the 1.25 nipple. Use a clean punched hole on the wireway with a sealing locknut on the outside and a grounding locknut on the inside. This will comply with 250.92 and avoid needing bonding bushings and jumpers. This will save you a lot of work and material cost.

Yes but my side of the nipple that is on the meter side, the smallest KO is 2", so I was forced to use a 2" to 1.25" reducer for each meter housing, which by code forces me to use a bonding bushing.

I did bring up the idea of using a grounding lock ring with my boss last week. My bosses argument is that it might fail inspection because an inspector might not like the idea of a grounding lock ring being used on a 2" to 1.25" reducer. He just didn't want to take the risk. I tend to agree, I can see an inspector failing it. The lock ring ground screw would be making contact with the reducer, not the meter housing. An inspector could make the argument that there isn't a good enough bond.

Edit: Or maybe I'm wrong? Maybe it isn't required to use a bonding bushing or grounding lock nut on a reducer. Hmm I need to look more into that, maybe all this time I'm thinking wrong?

 

[JasonCo]

The way I see it with a reducer washer, there's no way it can make good bond with the metal housing. The reducer washer is making contact with the paint, not the metal. I'm forced to use a bonding bushing, if anything to guarantee a green tag. That's why I'm forced to go with the plan in my OP.

 

[texie]

Yes but my side of the nipple that is on the meter side, the smallest KO is 2", so I was forced to use a 2" to 1.25" reducer for each meter housing, which by code forces me to use a bonding bushing.

I did bring up the idea of using a grounding lock ring with my boss last week. My bosses argument is that it might fail inspection because an inspector might not like the idea of a grounding lock ring being used on a 2" to 1.25" reducer. He just didn't want to take the risk. I tend to agree, I can see an inspector failing it. The lock ring ground screw would be making contact with the reducer, not the meter housing. An inspector could make the argument that there isn't a good enough bond.

Edit: Or maybe I'm wrong? Maybe it isn't required to use a bonding bushing or grounding lock nut on a reducer. Hmm I need to look more into that, maybe all this time I'm thinking wrong?

Isn't the other end of the nipple attaching to a clean punched hole? You only need to have 250.92 bonding on one end.
No, bonding lock nuts are worthless with reducing washers.

 

[JasonCo]

Isn't the other end of the nipple attaching to a clean punched hole?

You're right it is. I see what you're saying. I just thought it was code that you are required to bond if you are using reducer washers.

Edit:

250.92 (B) Method of Bonding at the Service. Bonding jumpers meeting the requirements of this article shall be used around impaired connections, such as reducing washers or oversized, concentric, or eccentric knockouts. Standard locknuts or bushings shall not be the only means for the bonding required by this section but shall be per mitted to be installed to make a mechanical connection of the raceway(s).

 

[texie]

Oh... I see what you're saying. I just thought it was code that you are required to bond if you are using reducer washers.

Edit:

The washers are fine if the other end is bonded per 250.92 and the meter socket has a bonded neutral.

 

[JasonCo]

Yes but I still need to use a bonding jumper for the reducing washers as per 250.92 (B)?

 

[kwired]

Yes but I still need to use a bonding jumper for the reducing washers as per 250.92 (B)?

The other end of the nipple is bonded, the meter socket is bonded to the grounded conductor, so you really are not bonding around anything because both items you are trying to join together already are joined by the grounded conductor, you are only improving the parallel path through the raceway at the most.

If you do use grounding bushings use them in the gutter line them all up and run a straight bonding jumper through all of them instead of in and out of each meter enclosure.

 

[texie]

Yes but I still need to use a bonding jumper for the reducing washers as per 250.92 (B)?

NO

 

[JasonCo]

Well why are we just ignoring that code? I understand the fundamentals as to why you wouldn't need to, but that code says other means of bonding must be used for reducer washers. There is no exceptions listed in the code book. I do understand what you are saying, but why are we ignoring that 250.92 (B) rule, regardless of it's actual practicality?

 

[kwired]

Well why are we just ignoring that code? I understand the fundamentals as to why you wouldn't need to, but that code says other means of bonding must be used for reducer washers. There is no exceptions listed in the code book. I do understand what you are saying, but why are we ignoring that 250.92 (B) rule, regardless of it's actual practicality?

We are not ignoring anything, the nipple is bonded the meter can is bonded the only way the washers get any better bonding is if you attach something directly to them somehow. Bottom line is you are not depending on the washers to make any kind of bond. The grounded conductor is already bonding the meter can the nipple is or can easily be bonded in the gutter and only needs bonded at one point - usually one of the ends.

 

[JasonCo]

Believe me I 100% agree with you. I completely agree that bonding the reducer washer is completely pointless if you bond the other end of the nipple and both neutrals are bonded. Trust me I understand 100% and agree 100%. With that said, I just don't understand how we aren't ignoring that rule? The rule clearly states all reducer washers must be bonded, regardless of it's practicality. There is no exceptions listed in the NEC. I'm all for doing it the way you are saying, because it makes perfect sense. I have no argument if an inspector decides to fail me for ignoring 250.92 (B), technically speaking correct? This is all I'm saying, I absolutely agree with both of you though.

 

[kwired]

Believe me I 100% agree with you. I completely agree that bonding the reducer washer is completely pointless if you bond the other end of the nipple and both neutrals are bonded. Trust me I understand 100% and agree 100%. With that said, I just don't understand how we aren't ignoring that rule? The rule clearly states all reducer washers must be bonded, regardless of it's practicality. There is no exceptions listed in the NEC. I'm all for doing it the way you are saying, because it makes perfect sense. I have no argument if an inspector decides to fail me for ignoring 250.92 (B), technically speaking correct? This is all I'm saying, I absolutely agree with both of you though.

The washers are bonded - if RGS conduit with locknut on both sides it is bonded by the locknut(s). What is potentially impaired is washer to the meter enclosure connection especially if paint is not removed but meter enclosure is already bonded by the grounded conductor. Putting a grounding bushing on that end of the nipple doesn't change anything when grounded conductor was there to begin with.

 

[JasonCo]

Yeah true. I feel like for service entrance conductors they should put in exceptions for this, just so people like me don't sit here and complain haha

 

[texie]

Believe me I 100% agree with you. I completely agree that bonding the reducer washer is completely pointless if you bond the other end of the nipple and both neutrals are bonded. Trust me I understand 100% and agree 100%. With that said, I just don't understand how we aren't ignoring that rule? The rule clearly states all reducer washers must be bonded, regardless of it's practicality. There is no exceptions listed in the NEC. I'm all for doing it the way you are saying, because it makes perfect sense. I have no argument if an inspector decides to fail me for ignoring 250.92 (B), technically speaking correct? This is all I'm saying, I absolutely agree with both of you though.

You are misunderstanding the requirements. You are not bonding the washer but rather preventing from being the sole fault return path. But in this case the path is not required as the other end is bonded and the enclosure it is connected to is bonded to the neutral.
To use your logic how would a bonding bushing bond the washer anyhow?