Determing AWG Wire gauge

Post Reply | Watch this Post

Recently replaced a 20 amp breaker to a 15 amp. The breaker that was in the panel was feeding a hydronic boiler. The wire fused and burned out. I could smell the breaker and it smelled like fire. I didn't know the wire gauge size, so what is an acceptable method of determing it? I do know however that a 15 amp is allowed for 14/2 and a 20 amp is required for 12/2. Safety is my main objective here. Your help is appreciated !