kingpb
Senior Member
- Location
- SE USA as far as you can go
- Occupation
- Engineer, Registered
The motors in the wet well come with pre-attached/wired cable on the motor. The wet well design will have at least 12 air changes per hour, and it has been determined the area is Class 1, Div 2.
Proposed design includes bringing the cable out of the wet well by installing a PVC sch 80 conduit sleeve out the top of the well wall (horizontally), 90 deg bend up (min 18" above finished grade) and fasten in place for support. A min. 6" air gap will exist between the top of the conduit and bottom of a NEMA 4X JBX. Therefore the bottom of the JBX will be at least 24" above finished grade.
The cable will run through the conduit sleeve and terminate in JBX using a properly sized cable gland. A sealed fitting should not be required because the open end of the conduit to air. NEC 501.15(B)(2), Exception 2.
This installation will allow the cable to be removed for maintenance, without causing damage to a sealed fitting, which is required by permitting agency, eliminates the use of sealed fittings, and keeps corrosive gas out of the JBX by having the cable enter through a cable gland.
Client contends that the conduit should go from the wet well all the way into the bottom of JBX, and no sealed fittings are required. He is applying the last sentence of NEC 501.15(B)(2), Exception 2 for this, while, in my opinion ignoring the first part of the exception. Then he wants a sealed fitting to be used on the conduit going from the JBX to the motor starter. without the JBX being explosion proof.
My contention is that the client is misinterpreting Exception 2, as a whole, and that it does not allow a conduit to go from a classified area and connect into a JBX in an unclassified area without having a sealed fitting simply because of the last sentence. They have a bunch of facilities done this way, and thinks this one should be done the same.
Looking for second opinions before I politely explain to him, he's wrong.
Proposed design includes bringing the cable out of the wet well by installing a PVC sch 80 conduit sleeve out the top of the well wall (horizontally), 90 deg bend up (min 18" above finished grade) and fasten in place for support. A min. 6" air gap will exist between the top of the conduit and bottom of a NEMA 4X JBX. Therefore the bottom of the JBX will be at least 24" above finished grade.
The cable will run through the conduit sleeve and terminate in JBX using a properly sized cable gland. A sealed fitting should not be required because the open end of the conduit to air. NEC 501.15(B)(2), Exception 2.
This installation will allow the cable to be removed for maintenance, without causing damage to a sealed fitting, which is required by permitting agency, eliminates the use of sealed fittings, and keeps corrosive gas out of the JBX by having the cable enter through a cable gland.
Client contends that the conduit should go from the wet well all the way into the bottom of JBX, and no sealed fittings are required. He is applying the last sentence of NEC 501.15(B)(2), Exception 2 for this, while, in my opinion ignoring the first part of the exception. Then he wants a sealed fitting to be used on the conduit going from the JBX to the motor starter. without the JBX being explosion proof.
My contention is that the client is misinterpreting Exception 2, as a whole, and that it does not allow a conduit to go from a classified area and connect into a JBX in an unclassified area without having a sealed fitting simply because of the last sentence. They have a bunch of facilities done this way, and thinks this one should be done the same.
Looking for second opinions before I politely explain to him, he's wrong.
