hausdok Posted October 8, 2011 Report Posted October 8, 2011 Originally posted by Jim Port he neglected to install the bonding strap of the neutral bus to the back of the panel. 3 years later, I'm reporting it. The neutral is bonded to the meter can, so I think that may be why nothing bad happened? I suppose an apprentice made that error. Fresh out of school, he should know better. Click to Enlarge 72.37 KB Are you quite sure about that? I thought the code says that the grounded bus and the grounding bus may be bonded but not beyond the main disconnect. If the grounded conductors and grounded bus are isolated from the grounding bus and equipment grounding conductors why must they be bonded through the enclosure, if it's a situation where the code allows it under special conditions but doesn't require it? You say the neutral (bus?)(grounded bus) is bonded to the Myers hub but it looks more like the service grounding electrode conductor extends from the grounding bus through a hole at the lower right corner on the way to the service grounding electrode and passes through a bond clamp attached to the Myers hub. Have you got an establishing shot of that panel? ONE TEAM - ONE FIGHT!!! Mike
John Kogel Posted October 8, 2011 Report Posted October 8, 2011 Originally posted by Jim Port he neglected to install the bonding strap of the neutral bus to the back of the panel. Are you quite sure about that? I thought the code says that the grounded bus and the grounding bus may be bonded but not beyond the main disconnect. If the grounded conductors and grounded bus are isolated from the grounding bus and equipment grounding conductors why must they be bonded through the enclosure, if it's a situation where the code allows it under special conditions but doesn't require it? You say the neutral (bus?)(grounded bus) is bonded to the Myers hub but it looks more like the service grounding electrode conductor extends from the grounding bus through a hole at the lower right corner on the way to the service grounding electrode and passes through a bond clamp attached to the Myers hub. Have you got an establishing shot of that panel? ONE TEAM - ONE FIGHT!!! Mike What I see is the bonding strap was not installed. I expect to see one in a combination service panel such as this, where the service conductors come in from the meter box to a main breaker, that's the main disconnect. In this situation, I am pretty sure the neutral bus must be bonded to the panel, in both the US and Canada. I said that the neutral was bonded at the meter only because that would be correct. I never get to see behind the meter. (Will attach a pic later)
Jim Port Posted October 13, 2011 Report Posted October 13, 2011 Originally posted by Jim Port he neglected to install the bonding strap of the neutral bus to the back of the panel. 3 years later, I'm reporting it. The neutral is bonded to the meter can, so I think that may be why nothing bad happened? I suppose an apprentice made that error. Fresh out of school, he should know better. Click to Enlarge 72.37 KB Are you quite sure about that? I thought the code says that the grounded bus and the grounding bus may be bonded but not beyond the main disconnect. If the grounded conductors and grounded bus are isolated from the grounding bus and equipment grounding conductors why must they be bonded through the enclosure, if it's a situation where the code allows it under special conditions but doesn't require it? You say the neutral (bus?)(grounded bus) is bonded to the Myers hub but it looks more like the service grounding electrode conductor extends from the grounding bus through a hole at the lower right corner on the way to the service grounding electrode and passes through a bond clamp attached to the Myers hub. Have you got an establishing shot of that panel? ONE TEAM - ONE FIGHT!!! Mike The picture shown is the service panel, or what you called the main disconnect. As such the bonding and grounding would take place in this panel. Look at the uninstalled bond strap laying in the lower left corner.
hausdok Posted October 13, 2011 Report Posted October 13, 2011 Yes, I understand why they are bonded there and why it's necessary to install the strap when the grounded and equipment-grounding conductors are both mounted on the grounded (neutral) bus at the main disconnect. My question is, and I'm hoping Douglas will answer it, must the bonding strap be installed if the grounded conductors are all isolated on the grounded bus and the equipment-grounding conductors are all on the grounding bus and they are not mixed? ONE TEAM - ONE FIGHT!!! Mike
Chad Fabry Posted October 13, 2011 Author Report Posted October 13, 2011 (4) Path for Fault Current. Electrical equipment, wiring, and other electrically conductive material likely to become energized shall be installed in a manner that creates a low-impedance circuit from any point on the wiring system to the electrical supply source to facilitate the operation of overcurrent devices should a second ground fault from a different phase occur on the wiring system. The earth shall not be considered as an effective fault-current path. I'm pretty sure this means that the ground has to be connected to the grounded conductor. If it doesn't, I'm hoping for a discussion...
hausdok Posted October 13, 2011 Report Posted October 13, 2011 (4) Path for Fault Current. Electrical equipment, wiring, and other electrically conductive material likely to become energized shall be installed in a manner that creates a low-impedance circuit from any point on the wiring system to the electrical supply source to facilitate the operation of overcurrent devices should a second ground fault from a different phase occur on the wiring system. The earth shall not be considered as an effective fault-current path. The group that wrote that needs to be horse whipped. Why can't they just put it in simpler terms without all of the twenty five cent words and passive language so that even a plant can understand it? ONE TEAM - ONE FIGHT!!! Mike
Marc Posted October 13, 2011 Report Posted October 13, 2011 As I understand Mike's question, the purpose of the strap is simply to bond the metal enclosure of the main panel. If the neutral wires and the equipment grounding wires happen to be secured on separate bus bars that are electrically bonded together then it doesn't matter which one is used by that strap to bond the metal enclosure. Did I get the question right or did I miss the train? Marc
Chad Fabry Posted October 13, 2011 Author Report Posted October 13, 2011 As I understand Mike's question, the purpose of the strap is simply to bond the metal enclosure of the main panel. If the neutral wires and the equipment grounding wires happen to be secured on separate bus bars that are electrically bonded together then it doesn't matter which one is used by that strap to bond the metal enclosure. Did I get the question right or did I miss the train? Marc I think Mike asked if the neutrals and grounds must be bonded at the service disconnect.
Jim Katen Posted October 14, 2011 Report Posted October 14, 2011 Yes, I understand why they are bonded there and why it's necessary to install the strap when the grounded and equipment-grounding conductors are both mounted on the grounded (neutral) bus at the main disconnect. My question is, and I'm hoping Douglas will answer it, must the bonding strap be installed if the grounded conductors are all isolated on the grounded bus and the equipment-grounding conductors are all on the grounding bus and they are not mixed? ONE TEAM - ONE FIGHT!!! Mike Not Douglas, but I'll try. If you're talking about the service disconnect, then yes, the equipment grounding conductors (the bare wires) must be bonded to the service disconnect enclosure and to the grounded conductor (the white wire).
Chad Fabry Posted October 15, 2011 Author Report Posted October 15, 2011 Jim, Can you direct me to the NEC cite for that requirement?
Jim Katen Posted October 15, 2011 Report Posted October 15, 2011 Jim, Can you direct me to the NEC cite for that requirement? Try 250.24(B)
Chad Fabry Posted October 15, 2011 Author Report Posted October 15, 2011 Thanks- for those of you who do not have the NEC ?250.24(B) (B) Main Bonding Jumper. For a grounded system, an unspliced main bonding jumper shall be used to connect the equipment grounding conductor(s) and the service-disconnect enclosure to the grounded conductor within the enclosure for each service disconnect in accordance with 250.28.
charlieb Posted October 21, 2011 Report Posted October 21, 2011 I ran across this during my travels last week. Unfortunately, I was unable to open it before the tour guide found me =( Click to Enlarge 14.03 KB Click to Enlarge 19.85 KB
palmettoinspect Posted October 25, 2011 Report Posted October 25, 2011 Click to Enlarge 97.16?KB Click to Enlarge 51.59?KB Wow! I wonder how hot this panel gets?
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