IMH the ERS are applicable, like any other rules, only when explicitly indicated by one of the following: class rules, NoR/SI, national prescriptions.

Agree with Jacopo

I agree. The Equipment Rules of Sailing don't apply at an event unless they are called up in NOR Section 1 Rules, or by Class Rules or some higher level authorities.

ERS Introduction Applicability
The ERS are invoked by:
(a) Class Rules.
(b) A notice of race and sailing instructions.
(c) Prescriptions of an MNA for races under its jurisdiction.
(d) World Sailing Regulations,
(e) World Sailing Racing Rules of Sailing, or
(f) Other documents that govern an event.

Definitions in the ERS apply to some extent in interpreting rules:

RRS Introduction Terminology last sentence

Other words and terms are used in the sense ordinarily understood in nautical or general use. For a source of the nautical sense of a word, a reader may refer to The Equipment Rules of Sailing.

The definition of Equipment Regulations in the ERS sets out to create a new sort of rule that can be 'published' by a technical committee.

But according to the RRS, the only entities at an event that can make rules for the event are the Organising Authority, via the Notice of Race (RRS 89.2(a)) and the Race Committee, via the Sailing Instructions (RRS 90.2(a)).

A Technical Committee is not, by the RRS, which constitute it, given any power to make rules or publish them.

So, if a Technical Committee wants to make enforceable Equipment Regulations it is necessary that 'Equipment Regulations [published by the technical committee]' be included in the list of other documents that govern the event in the NOR.