Double tap buss bars?

Saw a panel today with several double taps at neutral buss bar and several at grounding buss bar. Is this improper. Nachi class only discusses double tap breakers.

I’m answering my own question. Looked it up in my code book (2006 IRC). Section E3306.9 Terminals. Connections to terminals shall be made without damaging the conductors, … Terminals for more than one conductor shall be identified for the application.

Commentary States: …most modern equipment such as panel boards has terminal strips with sufficient number of terminals to connect all necessary circuit conductors. In some cases it may be necessary to install additional terminal strips to connect each conductor under a separate terminal.

There is a more specific one if you want. NEC 408.41

Many EGC buses are listed for 2 or 3 conductors.

This is a 20 year old sq D. No evidence of special made for double taps. Lots of other items going on inside this panel. Will be referring to electrician.

Square D has be listed for multiple grounding conductors for over 30 years IIRC.

Which panels? Could you post the listing. Either way there has been good rational posted here that does discourage double tapping of all types.

Don’t confuse groundING with groundED:wink:


The correct term when referring to more than one conductor under a bus screw is lug.

Double lugged neutrals(grounded conductors) is not permitted.

However you can have more than one grounding conductor(safety ground) under a bus screw.

Is that clear? :wink:

I think its interesting the internal labels on this GE panel only refers to single wires for torque tightening.

That is (one of) the reasons why only single conductors are allowed under a lug… multi conductors can and will lose torque over time (grounded conductors). I believe up to three “grounding” conductors may be lugged, but they must be of the same gauge!