How Many Ground Wires Can Go Under One Screw in a Panel?
A user asked the app how many ground wires can be landed under one screw in a panel. The honest answer is: whatever the panel label says, and for most residential panels that means up to three equipment grounding conductors of the same size under a single ground bar terminal. Neutrals are a different story entirely, and mixing up the two rules is one of the most common findings on panel inspections.
The listing controls the count
NEC 2023 110.14(A) requires terminals to be used with the number and size of conductors they are listed for, and 110.3(B) makes following the listing mandatory. Panel manufacturers publish this on the label inside the door or the terminal kit instructions. The typical ground bar on Square D, Eaton, Siemens, and GE loadcenters is listed for one 14 to 4 AWG conductor per hole, or up to three 14, 12, or 10 AWG grounds in a single hole when they are the same size. Some labels allow combinations like two 12 AWG plus one 14 AWG; others do not. If the label is unreadable, the safe move is one wire per hole or an added ground bar kit, which costs a few dollars and screws into factory tapped holes.
Neutrals: strictly one per terminal
Section 408.41 requires each grounded conductor to terminate in an individual terminal. Doubled neutrals are a real hazard, not a paperwork issue. When you pull one neutral out of a shared hole for service work, the other circuit is interrupted, and on a multiwire branch circuit an opened neutral puts series 240 volts across 120 volt loads and cooks electronics. The same section allows a neutral and a ground to share a bar in service equipment where the bonding is in place, but never two neutrals in one hole, and in a subpanel the neutrals must land on an isolated bar with the bonding screw removed.
Field notes
Torque matters as much as count. 110.14(D) requires terminations to be torqued to the manufacturer value, which is printed right next to the terminal listing on the label. Grounds doubled up beyond the listing, or a 8 AWG forced into a hole with two 12s, will pass current fine on a good day and fail during a fault, which is exactly when the connection has one job to do. When a remodel fills the ground bar, add a bar rather than triple stacking terminals not listed for it.