NEC ECC: Who sets up the adjudicators contract?

If we are going to end up in adjudication, who (as in Client or Contractor) actually sets up the adjudicators contract? Who physically sets up the documents, who gets them to sign it etc?

The contract is silent on who prepares the Adjudication Contract, it merely puts an obligation on the Parties (Employer and Contractor) to appoint the Adjudicator under the NEC Adjudicator’s Contract.