Main bonding strap

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guschash

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What I have is a subpanel right next to the main panel. short nipple connecting panels. Its four wires, and there is a bonding strap on the grounding bar. My question is, is this need. We need to bond the panel box, right because it is raised up on plastic insulation. Looking in my workbook exhibit 250.19 shows a green bonding screw in both panels, but this is for a remote building.
 
The second panel should not have the neutral bonded to the EGC.

4 wire? Is this a 1 ph panel ( 2 hot, neutral, EGC) or 3 ph ( 3 hots, neutral)?
 
Does the second panel have a OverCurrent Protective Device that disconnects the electrical service ("unfused conductors") from the second panel? If so, then the neutral gets bonded to the equipment ground.

However, if the conductors supplying the second panel come from a fuse or breaker in the "main" panel, then the second panel neutral is not bonded to the equipment ground.
 
guschash said:
1-phase. Isn't the sub-panel bonded anyways by the short nipple from the main panel.
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The nipple itself may be good as an bonding connection, but the locknuts or other mechanical connection of the nipple to the enclosure are OK sometimes, and sometimes not. What's the voltage? Where's the service disconnect(s)?
 
al hildenbrand said:
Does the second panel have a OverCurrent Protective Device that disconnects the electrical service ("unfused conductors") from the second panel? If so, then the neutral gets bonded to the equipment ground.

However, if the conductors supplying the second panel come from a fuse or breaker in the "main" panel, then the second panel neutral is not bonded to the equipment ground.
Click to expand...

Side by side panels that have both neutrals bonded to the enclosure isn't uncommon. . 95% of the time it's a double service main supplied separately from the common meterbase or from service taps out of a common trough. . But this doesn't appear to be your situation.

This install has a nipple between panels and one panel powered first. . You could be dealing with an installation where the service conductors hit the service main OCPD and load side of OCPD then powers the breaker busses and the feedthru lugs. . The other possibility is multiple conductor lugs for the service conductors and some conductors landed there are bringing power in from the transformer while others are heading out to panel #2.

al hildenbrand said:
Does the second panel have a OverCurrent Protective Device that disconnects the electrical service ("unfused conductors") from the second panel?
Click to expand...

Turn off the main breaker on panel #1, is panel #2 still energized ?
 
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guschash said:
What I have is a subpanel right next to the main panel. short nipple connecting panels. Its four wires, and there is a bonding strap on the grounding bar...
We need to bond the panel box, right because it is raised up on plastic insulation. Looking in my workbook exhibit 250.19 shows a green bonding screw in both panels, but this is for a remote building.
Click to expand...

If you're asking about the subpanel, and this equipment is considered one unit with the service disconnect, yes if not considered one unit then no, and if in doubt no.

Notice 250.24(A)(5) & 250.142(B), the goal is to eliminated objectionable current on non current carrying items. If a neutral parallel path exists with metal conduit and frames touch voltage will exist as well.
 
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