Nipple Between Boxes

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ESolar

Senior Member
Location
Eureka, CA Humboldt County
Occupation
Electrician/Contractor
I have a surface mount panel and a jbox inside the wall behind panel with a close nipple connecting the two. See picture. My questions are: Do the two sealer lock nuts suffice for connection to the panel (secure and bonding)? If I use a PVC J-Box, does one lock nut suffice to secure the nipple to the J-Box? Or what needs to be done? If I use a steel box I assume that it has to be bonded. Do two lock nuts on the J-Box suffice for grounding a steel box? The J-Box is being used to secure and route UF and SER cable - no splices.
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For the junction box a metal bushing on the inside and a locknut on the outside would suffice. Otherwise you need a locknut on both sides of the box. BTW nice graphic. (y)
 
infinity said:
For the junction box a metal bushing on the inside and a locknut on the outside would suffice. Otherwise you need a locknut on both sides of the box. BTW nice graphic. (y)
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No problem with PVC j-box, correct? I don't know how to tighten the two nuts when the box is flush with the back of the wall. That's why I drew one lock nut. I can put both on and tighten the inside nut very tight, which would create a secure connection and pull the box tight against that outside nut, in effect tightening it. But it would not necessarily be teeth in the metal tight. Hence the question about PVC j-box - no need to bond to that.
 
ESolar said:
I have a surface mount panel and a jbox inside the wall behind panel with a close nipple connecting the two. See picture. My questions are: Do the two sealer lock nuts suffice for connection to the panel (secure and bonding)? If I use a PVC J-Box, does one lock nut suffice to secure the nipple to the J-Box? Or what needs to be done? If I use a steel box I assume that it has to be bonded. Do two lock nuts on the J-Box suffice for grounding a steel box? The J-Box is being used to secure and route UF and SER cable - no splices.
View attachment 2563780
Click to expand...
If its 480V, the nipple needs locknuts on inside and outside if its metal box
 
lordofthisworld said:
If its 480V, the nipple needs locknuts on inside and outside if its metal box
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infinity said:
Why would the voltage matter?
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Only if the nipple is also the EGC to the junction box.

Lets assume the panelboard cabinet is properly connected to an EGC or is the service equipment enclosure. If the nipple and the j box are metallic they both need bonded but there are options on how to do it.
One the most common methods (some even think this is the only possibly method) is double locknut on both which when done this way the nipple can also be considered to be the EGC between the two enclosures.

You could have double locknut on just one end which satisfies bonding the nipple but must also have a bonding jumper through the nipple to bond between the two boxes .

Could be other slight variances but bottom line is all three items must have something solidly bonding them together.

The 480 volt thing comes in to play when you encounter concentric/eccentric KO's being involved and you are not using the largest size opening, though some cases they may be listed as acceptable for bonding in that situation.
 
kwired said:
Lets assume the panelboard cabinet is properly connected to an EGC or is the service equipment enclosure. If the nipple and the j box are metallic they both need bonded but there are options on how to do it.
One the most common methods (some even think this is the only possibly method) is double locknut on both which when done this way the nipple can also be considered to be the EGC between the two enclosures.

You could have double locknut on just one end which satisfies bonding the nipple but must also have a bonding jumper through the nipple to bond between the two boxes .
Click to expand...
RMC is required to be secured to the box and therefore requires two locknuts when entering a box or a metal bushing on the inside and a locknut on the outside. Voltage level doesn't matter unless as you've mentioned you're dealing with eccentric or concentric KO's.
 
infinity said:
RMC is required to be secured to the box and therefore requires two locknuts when entering a box or a metal bushing on the inside and a locknut on the outside. Voltage level doesn't matter unless as you've mentioned you're dealing with eccentric or concentric KO's.
Click to expand...
With the wall between them single locknut on each end of the nipple would secure it reasonably well in many cases, however would not be reliable enough bonding connection.

Might need to read between the lines a little here both for accepting as well as rejecting it though. JMO.
 
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