The victory was arguably the best all round performance that United had produced this season and was the perfect response to the recent slump in form that saw United lose three fixtures in succession.
Ryan McBride and Casey Ham returned to the starting XI and it was the former who opened the scoring.
A thumping header from Sean Ray cannoned back off the underside of the crossbar, but McBride was in the right place at the right time to react quickest and thrash the ball home.
Ham had a fantastic chance to double United's lead just two minutes later, but he placed his effort wide of the post when well placed.
With four minutes of the second half played, Jason Taylor cut in from the left and saw his effort bounce over the visiting 'keeper but it bounced back off the post.
Moments later, Ham did double United's lead as he confidently slotted past Fernandes in the Arundel goal.
A third goal for United came soon after when Jack Divall was bundled over in the penalty area.
Wes Tate stepped up and sent Fernandes the wrong way as United looked on course for another cup upset.
Arundel offered very little attacking threat, despite being among the early season pacesetters in SCFL Division One and the closest they came to working Grant Young was a 63rd minute free kick from Grant Thetford that whistled past the outside of the post.

UNITED: Young; Franklin, S.Dartnall (Snashall 80), Loft ©, Ray, B.Dartnall (Sturgeon 79), Divall, Tate, McBride, Ham (L.Rogers 74), Taylor