Shallow well pump house electrical

[ahall1970]

Hello, I am helping an friend and need some assistance. The situation is, there is a water well pump house with a 1/2HP shallow well pump. The pump house has a dedicated breaker (30amp), so proper romex runs from the breaker panel to the pump house and was connected to an outlet. The pump has a plug cord attached to the pump pressure switch and then plugs into the wall outlet. After however long its noticed that the breaker tripped. Phil got tired of the breaker tripping so he ran an extension cord from an outside outlet (on a 15 or 20 amp breaker which also has indoor home lights and outlets) to the pump house and plugged in the pump and that breaker has never tripped with all the lights, outlets and pump on that breaker.

I thought maybe the pump house outlet was bad so I changed the outlet, same problem. Now when anything else (lights, fan, tools) is plugged into the outlet for the pump house, the breaker never trips. It only trips with the pump. The pump is 6 years old.

Any advice to help Phil would be appreciated so he can get the extension cord off the ground and uses the dedicated breaker as it was set up for.

Thanks,
Alex

 

[msitekkie]

Just some thoughts that might help - is there RCD protection on one circuit and not the other? An RCD/RCBO will trip when there is an imbalance between live and neutral (leak to earth) whereas an MCB is designed to trip on an overload.
One scenario might be that the current configuration does not have RCD protection and is not seeing a fault that the tripping "breaker"/RCD/RCBO does.

With the RCD/RCBO protection, I know when I fitted my pump the manufacturers specified a Type A RCD which can cope with DC currents you might get from a pump. Until relatively recently type AC breakers were still often used in the UK, but these are designed to cope with mainly resistive loads (e.g heating element/lamp) rather than devices containing electronics.
Video here explaining Type A vs AC RCDs.

I hope this is some help,
Robin