Ray Taylor, aged 61, took the measure in a bid to deter thieves from breaking into his van – after losing more than £2,000 worth of equipment.
The system is equipped to the electrician's Citroen Dispatch, with would-be offenders getting a shock.
WATCH: The shocking deterrent in action
But West Midlands Police warned against the use of the device saying an offence could be committed by its installation and use.
Ray, from Fallings Park, said: "My van has been burgled before so I thought I would set an alarm.
"And whilst the alarm was going off, some cheeky person tried to open the back door of the van.
"So it was not protected – so I decided to protect it via the shocker."
The shocker was fitted around a month ago – with the system designed entirely by the electrician.
"It was totally designed and created by myself," he said.
"It took me about six hours to fit it – I don't mess about, I know the nature of wires.
"The shocker is disabled until they set the alarm off and then the shocker comes into effect.
"It's dead until the break-in – like if someone tries to break the doors with a crowbar.
"The sirens are very loud, too. There's the siren in the bumper and two in the back.
"I thought I would put some security on it because this is epidemic and people have been trying doors."
Any attempt to break-in to the van will set off the alarm and spark the system into life.
The sub-contractor, who works in Wolverhampton, said it was a "great" invention which he hoped other traders would use in future.
He said: "I think it's a great invention – it could help a lot of other people out.
"I just need someone who will back it.
"I also want to protect other traders as well from this pain – we're just sick of it.
"The alarm system has been in place for six to eight months, but the shocker is an addition I've put on in the last months.
"It says 'dangers live terminals' so if they want to try it while the alarm is going off, it's up to them."
Mr Taylor said fitting the shocking system was a 'grey area', in terms of whether the police had approved it.
"It's a grey area, but farmers can put electric fences up with a sign on it.
"Mine says 'touch this and you'll get a shock' essentially – it's just the same."
West Midlands Police said any complaint against the system would be handled on a "case by case" basis.
A spokesman for the force said: "It is possible that a criminal offence could be committed by the installation and use of such a device.
"Any complaint from a member of the public however will be dealt with on a case by case basis.
"Such modifications may also affect motor insurance policies, if such modifications do not meet safety regulations.
"Aside from this, any member of the public affected by use of the product could potentially issue a civil claim."