Grounding at a Rectifier? Help?

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mattkc

Member
Location
KC, MO
I have a few questions on the bonding/grounding at a rectifier site. Here's what I have: 240v 1phase 3-wire drop from transformer to a disconnect. The 2 ungrounded conductors are fused and the grounded conductor lands on a bus bar in the disc. Then, 3-wires (2 black ungrounded & 1 white grounded) go to a rectifier, which is used for cathodic protection. . The 2 black wires land on a 2-pole bkr and the white wire lands on a terminal strip that is bonded to the enclosure. There is a ground rod connected to the rectifier enclosure and the enclosure and there is also 120v circuit being used in the rectifier enclosure. Is there code violations here?? I thought the ground rod and grounding electrode conductor as well as main bonding jumper should be in the first available disconnecting means and then a grounded conductor and egc are seperate from that point on. Can anyone please help me with this as this is the first part of my problem??
 

Smart $

Esteemed Member
Location
Ohio
I have a few questions on the bonding/grounding at a rectifier site. Here's what I have: 240v 1phase 3-wire drop from transformer to a disconnect. The 2 ungrounded conductors are fused and the grounded conductor lands on a bus bar in the disc. Then, 3-wires (2 black ungrounded & 1 white grounded) go to a rectifier, which is used for cathodic protection. . The 2 black wires land on a 2-pole bkr and the white wire lands on a terminal strip that is bonded to the enclosure. There is a ground rod connected to the rectifier enclosure and the enclosure and there is also 120v circuit being used in the rectifier enclosure. Is there code violations here?? I thought the ground rod and grounding electrode conductor as well as main bonding jumper should be in the first available disconnecting means and then a grounded conductor and egc are seperate from that point on. Can anyone please help me with this as this is the first part of my problem??
Is the drop a service drop?

If yes, there needs to be a GES (grounding electrode system) established at the building or structure served. It can be connected to the grounded conductor at any point(s) along the service entrance conductors, including the service disconnecting means.

There must be a main bonding jumper located in the disconnecting means, connecting grounded and GES to the EGC.

On the load side of the service disconnecting means, the grounded conductor(s) and equipment grounding system must remain electrically isolated (aka insulated) from each other.

Conductors to the rectifier enclosure must be accompanied with an EGC. An auxiliary grounding electrode is permitted at the rectifier enclosure.

If not a service drop, will cover requirements upon verification.


PS: Welcome to the forum :thumbsup: (just in case I missed your first post :D)
 

mattkc

Member
Location
KC, MO
Thanks for the response. Yes, this is a service drop from a transformer and the way you described bonding and grounding at the first available disconnecting means is what I thought. Unfortunately, my company has dozens of these remote rectifiers installed with no EGC from the disconnect to the rectifier. The grounded conductor is bonded to the EGC and GEC at the rectifier. I guess these will all need to be rewired. I also have a question regarding a 120v single phase ckt being installed on the load side of the disc. As I mentioned the ungrounded conductors are fused. At one of the rectifier sites the disconnect has a black wire piggy backed to the load side of one phase of the 240v system. Then a white and green wire from the ungrounded terminal to a recptical in an enclosure 10 feet away. This just doesnt seem right to me... Your thoughts??? Thanks for the help in advance. I've received a lot of useful info from this site over the years but I never commented.
 

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
Thanks for the response. Yes, this is a service drop from a transformer and the way you described bonding and grounding at the first available disconnecting means is what I thought. Unfortunately, my company has dozens of these remote rectifiers installed with no EGC from the disconnect to the rectifier. The grounded conductor is bonded to the EGC and GEC at the rectifier. I guess these will all need to be rewired. I also have a question regarding a 120v single phase ckt being installed on the load side of the disc. As I mentioned the ungrounded conductors are fused.
Depending on the install it may be legal. Up until '05 it was legal to re-bond the neutral at a remote panel. It may be allowed to continue in some areas and as long as there are no metallic paths between the first disconnect and the remote panel
At one of the rectifier sites the disconnect has a black wire piggy backed to the load side of one phase of the 240v system. Then a white and green wire from the ungrounded terminal to a recptical in an enclosure 10 feet away. This just doesnt seem right to me... Your thoughts??? Thanks for the help in advance. I've received a lot of useful info from this site over the years but I never commented.
Are you talking about a wire tapped off one of the phases at the service disconnect or at the remote panel?
 

mattkc

Member
Location
KC, MO
As for rebonding, there is RMC from the disc to the rectifier. I'm quite confused on this because it seems as though the rectifier is designed this way. The grounded (white) conductor from the disc lands in rectifier enclosure and bonds to case. Then the case or enclosure seems to be where everything in the enclosure gets it's EGC or Nuetral. ????
 

Smart $

Esteemed Member
Location
Ohio
As for rebonding, there is RMC from the disc to the rectifier. I'm quite confused on this because it seems as though the rectifier is designed this way. The grounded (white) conductor from the disc lands in rectifier enclosure and bonds to case. Then the case or enclosure seems to be where everything in the enclosure gets it's EGC or Nuetral. ????
Is this a custom designed rectifier or off-the-shelf type, which you can provide make/model and perhaps link to documentation?

As Dave points out, it may be a matter of when it was manufactured and/or installed. However, there was never a time where a grounded system was not required to have a GES connected at or before the service disconnecting means and an MBJ there also.

There are some rectifier systems that are grounded (required or optional), but as far as Code goes, a non-isolated rectifier system connected to a grounded AC-supply system is considered grounded without additional connection to grounding. What is in question here is whether there is isolation between supply and rectifier?
 
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