Oil boiler keeps tripping when it rains?

[dc9811]

We've had a Grant Thornton oil boiler for about 5 years and suddenly it trips the electricity when it rains? The unit is in a wood shed and the exhaust goes out the wall horizontally. I can't see any water ingress in the machine, so at a real loss......and very cold..!!!!

 

[Basher]

It could be a fault in the electrical installation of your house, in the cable going to the shed, or in a junction box on that run, or damage to the cable etc, especially if it is an RCD tripping, not an MCB. An insulation test of the circuit would confirm (or not) but this requires a specialist tester. Is there a wiring centre or programmer on the wall in the shed? Time for an electrician, unless you can find evidence of water at a junction box or at cable terminations.
If it only trips when the boiler fires up, it could still be a latent leakage in the cable being increased by the same from the boiler when it activates. Electrical testing with the right equipment by someone competent is the way to find the problem!

 

[SimonG]

As above, highly unlikely to be boiler if it only happens when it rains. Check the supply.