Jac is able to smell oil and hydrocarbon gases through earth and tarmac, saving engineers from digging a number of holes as they try to find the source of the problem.

While cables are typically buried at 40-80cm below ground, the springer spaniel has been known to discover a fault two metres deep and his sensitive nose can sniff out as little as a couple of drops of oil. He has been trained at a substation in the town of Renfrew near Glasgow, under Spen's supervision. 

Overall, Jac has had a 100 per cent success rate in finding faults on 30 occasions, according to Scott Mathieson, planning and regulation director at Spen.

When a fault is identified, Jac pinpoints its location by pointing with a front paw

When a fault is identified, Jac pinpoints its location by pointing with a front paw

When a fault is identified, Jac pinpoints its location by pointing with a front paw /SPEN

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