A police officer who was caught driving at 98mph in a 50mph zone claimed the speed limit was not enforceable because the signs were not lit.
Sgt Craig Nicholas Jones, an organised crime officer with North Wales Police, was taking a prisoner from Colwyn Bay to Caernarfon when he was stopped.
The 40-year-old denied speeding but was was convicted by Llandudno magistrates.
His 90 day driving ban, along with £500 fine and £1,000 costs, have been lifted pending an appeal at crown court.
The court heard he had been driving along the A55 dual carriageway when he was stopped late at night on 1 April.
Sgt Jones's barrister Simon Gurney claimed the 50mph signs on the stretch of the road at Colwyn Bay should have been illuminated "and fall foul of the regulations".
Deputy district judge Timothy Gascoyne, told the police officer: "I'm satisfied you were speeding on the night in question and the signage was sufficient to give you adequate notice of the speed limit."
He added that one sign was under a street lamp.