The jury at Cardiff Crown Court convicted Peter Ellis, 34, a property developer, self-employed builder and DIY enthusiast, after being told he hatched the plot to pocket a pounds 600,000 insurance pay-out and set up a new life with his unsuspecting mistress.
The court was told his former wife, Lisa, 32, had leapt from her bath in panic after a blue flash sent a numbing sensation through her leg and melted the plug chain.
Sentencing him to 15 years for attempted murder, which Ellis had denied, and three years consecutively for 11 charges of theft, forgery and deception, which he had admitted, Mr Justice McKinnon said it was only by a miracle that his ex-wife had escaped death. She would almost certainly have been killed had she touched anything as she jumped from the water.
'You have shown yourself to be a callous, scheming, devious and evil man who carefully planned what you thought was to be the perfect crime,' Judge McKinnon told Ellis.
The judge said a severe sentence was called for, adding that Ellis, of Rhiwbina, near Cardiff, had failed to hoodwink the jury.
As she left the court, Mrs Ellis, who is now divorced, said: 'He deserves all he got. I am very, very satisfied with the sentence.
'I have had a year of absolute torment, not to mention the years before. I hope this is all over now and I can start to rebuild my life again.'
Ellis's mistress, Mrs Mary Francis, 40, a divorced estate agent he strung along for four years without telling her about his wife, was not in court to hear the verdict.
The judge said Ellis had 'cynically misled Mrs Francis over a number of years'. Unknown to her, he obtained details of her employer's bank account to set up one of his frauds, which netted him more than pounds 25,000 by forgery and deception, the court was told.
During the trial, the jury heard prosecution evidence that Ellis pushed live wires through the ceiling of a kitchen extension he was building and secretly connected them to the bath's over-flow pipe.
The judge said it was clear that Ellis had activated an electrical switch prepared earlier in order to run a live current through the bath.
Mrs Ellis had had a 'miraculous' escape, purely because she had not touched anything which would have earthed the connection, he said.
Ellis admitted stringing his mistress along, without telling her about his wife. But he told the court he had no intention of leaving his wife or their four-year-old daughter Florence. He had only taken out the insurance policies to provide for his family in the event of his own death, he insisted.Reuse content