Activities on a php.net property shall always be considered "representing the project" and hence fall under the jurisdiction of the Code of Conduct and Community Mediation Team. This includes any php.net mailing list.
While at a technology conference, the Code of Conduct is only considered to apply if and only if the person is demonstrably representing the project.
For example, merely speaking at a conference about PHP is not enough to be "representing the project". However, when speaking about the project itself (meaning internals functions, etc), while the talk is occurring the Code of Conduct shall apply.
This is not intended to limit the applicability of the Code of Conduct solely to the duration of the talk, however any violation that happens at a conference shall be assumed to not be representing the project unless there is significant and obvious evidence to the contrary.
On social networks, the Code of Conduct is only considered to apply if the context of the conversation makes it clear that the person represents the PHP project.
For example, merely having "PHP contributor" in an about or bio is not enough to be "representing the project". However, a conversation about the PHP project itself (including RFCs, etc) is enough to justify "representation".
In all cases, if an issue seems reasonably connected to a project matter, the Code of Conduct may apply depending on how strongly the connection is.
For example, if one person is involved in a heated discussion on internals@, and then immediately after starts harassing another participant on another channel with similar tone, the harassment may be considered a violation.
In no case should a casual connection be considered a violation (just because two people are both members of the project is not enough to form a connection).