A nipple is any piece of conduit 24 inches long or less, often a factory-threaded length of rigid or a short cut of EMT with connectors, joining a panel to a gutter, a disconnect to a transformer or one box to another. Code treats nipples specially: they may be filled to 60 percent of their area instead of 40, and conductors in them need no derating for the number of current-carrying wires. Factory rigid nipples come in set lengths, from close nipples threaded end to end up to 12 inches and beyond.
Use a two-inch nipple from the panel into the gutter, at that length you can fill it to 60 percent.
Also heard as
- conduit nipple
Related terms
Chase nipple
Short threaded fitting with a flat collar that joins two boxes or enclosures through their knockouts.
Rigid
Heavy-wall threaded steel conduit, the toughest raceway on site, used for services, exposed runs and hazardous areas.
Gutter
Sheet-metal trough with a removable cover used to splice, tap and route conductors next to panels and disconnects.