Ulster clubs occupy the top three places in Division Three as the race for promotion hots up.
Instonians made it six wins from six while City of Derry and Banbridge enjoyed home bonus point wins and Rainey made it a clean sweep for the Ulster clubs as they got a vital win to pull away from the foot of the table.
Inst rallied from losing a first minute try to win 18-13 at Highfield. Full back Scott Brown kicked eight points including the conversion on Robert Kirk's try to help Clem Boyd's men to a 13-5 half-time lead.
Inst had props Alan Whitten and Gary Mitchell sin binned in the second-half, but Kirk's second try proved decisive.
Derry's bonus point 25-22 win means they cut the Instonians lead to a single point. Barnhall pushed Bevan Lynch's men all the way and the scores were level at 12-12 at the break.
Winger William McCleery scored two of his side's four tries, full back Peter Henderson got a touch down and centre David Funston got the all bonus point score four minutes from time.
Banbridge left it late at Rifle Park to claim a 35-30 win over Sunday's Well. Robin Thompson scored a try, two conversions and kicked two penalties, but the Cork side lead 30-23 going into the last five minutes.
Prop Michael Combie went over before Dale Black won it for Bann with a converted try.
Rainey are up to 11th after recording a second successive win.
The Old Boys scored six tries in the 44-13 victory at Navan.
Michael Shields and Andrew Campbell both touched down twice, Richard McCrea and Ronan Devlin also crossed the line.