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400A service with (2) 200A panels

J

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Little Bill said:
Other than maybe a PVC box with thicker walls, I've never encountered an enclosure where a terminal adapter, or male adapter, as some call them, didn't come through enough to put a locknut and bushing on and have room after that. There is over a half inch of threads there after the locknut is on. Putting a sealing washer on the outside wouldn't lesson the thread exposure enough to prevent a locknut and bushing.
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Yes a sealing *washer* on the outside works fine but a sealing *locknut* on the outside takes up a lot more thread space. As I said YMMV. I'm lucky if I get a full 1/2" of thread on my connectors. The point was that putting a sealing locknut on the inside meets code.
 
Little Bill

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Semi-Retired Electrician
jaggedben said:
Yes a sealing *washer* on the outside works fine but a sealing *locknut* on the outside takes up a lot more thread space. As I said YMMV. I'm lucky if I get a full 1/2" of thread on my connectors. The point was that putting a sealing locknut on the inside meets code.
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Be hard to put a sealing locknut on the outside when the male adapter goes in from the outside! The sealing locknut would have to go inside.
The OP is not dealing with a nipple.
 
E

Elect117

Senior Member
Location
California
Occupation
Engineer E.E. P.E.
Violations (NEC 2020) -

352.30 - Securely fastened within 3' of boxes, conduit bodies and any other terminations. Since the code says within 3', any stick less than 3' still needs to be secured.

240.21 - ATS service OCPD is 400A and you have 4/0 (AL or CU) from it in parallel to separate panels of a distance greater than 25'. To correct this, you can use that wireway above the panel boards as a place to splice. So install Polaris taps and then you can run the 4/0 to the panel since it is less than 25' (and maybe less than 10').

334.30 / 314.17 - NM cable (Romex) needs to be secured before it enters the box.

250.109 / 250.122 / 250.148 / 314.40(D) / 314.4 - After the Polaris taps, the largest OCPD for the gutter box is 4/0 so the EGC needs to be sized to the 400A OCPD and bonded to the box with all of the other EGCs (with circuits that are spliced) in that box.
 
kwired

kwired

Electron manager
Location
NE Nebraska
Occupation
EC
From posts in the past - sealing locknuts apparently are listed for use with RMC/IMC and are supposed to be used on the outside of the enclosure.
They are not listed for use with PVC TA's or other "connectors" for that matter, though they are rather effective.

Someone posted an image of a catalog page that had the mentioned Carlon washers somewhat recently. FWIW, I remember seeing and commenting that the foot note on that page mentioned they are not listed. So essentially they are no better or worse from perspective of what is listed than the sealing locknut is. Myers hubs aren't listed for use with anything besides threaded RMC/IMC either, but would still likely be my choice of what to use in such a situation.
 
kwired

kwired

Electron manager
Location
NE Nebraska
Occupation
EC
Something I haven't seen mentioned yet is the length of conductors of each parallel set of conductors - the ones between the meter socket and the main breaker. The "inside" run is shorter therefore has less resistance. Doesn't seem it would be very significant but the reason you are supposed to keep them the same length is so they have as close as possible to same resistance and that will help make current divide equally. If there is enough difference this can result in one conductor being overloaded and the other one being lightly loaded when the draw is high. On a dwelling and depending on demand situations this maybe wouldn't happen very often.
 
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