The present invention provides for a multispur fieldbus isolator arrangement having a trunk (23) and in which each of a number of spur outlets (210) is connected to the trunk (23) by coupler isolators (24), where each coupler isolator (24) includes a removably mounted modular unit arranged for plug-in connection to the trunk (23) by means of a flameproof connection (29), and where a redundant coupler isolator can likewise be included for activation responsive to failure of a coupler isolator.