|Forum topic by woodbutcherbynight||posted 09-11-2016 03:30 PM||3022 views||0 times favorited||32 replies|
09-11-2016 03:30 PM
Yesterday my neighbor calls me in a panic to tell me how his breaker box caught on fire and wanted me to come up and see about getting a new one installed. As you can see from the picture the box got HOT, Chernobyl hot people! Those that work with electricity can tell immediately what was wrong, for those that do not allow me to explain what went wrong and how it applies to expansion of our own shop electrical.
They had replaced the HVAC service breaker at the compressor with a 30 amp breaker because the old one did not work. Inside the main breaker box this breaker was fed power from another 30 amp breaker. The unit was marked for a maximum of 20 amp breaker. In such cases more is NOT better. The problem was with the compressor, it has died and when engaged draws high amps trying to work. By using a 30 amp breaker verses 20 amp the wires of the circuit now carry more amps than needed creating HEAT. Bypassing the breaker and forcing the unit to work created a lot of heat from the high amp draw of a bad compressor. Left unchecked the box continued to heat up until melting point, then the fire starts. Fortunately the homeowner was able to respond quickly and put fire out, then kill the power. Four hours of work and we had rewired the new panel and had power minus a/c.
Lesson to be learned. Sure just upping the breaker to higher amps gives you what you need for power but the wiring to that breaker has limits. If and when a tool or device shorts the breaker with correct wire will support the brief overload and shut down. But when you ignore this and have smaller wire and higher amp breaker you create heat, and electrical fire can and often does result. The device need not be drawing excessive amps to create a problem. The combination of excessive draw on smaller wire with higher than rated breaker is a disaster in the making.
While I am not a pro in this regard I do know the basics and by ignoring them we invite disaster. Sure it costs money to have a pro come and do it correctly but the risk here is at minimum your shop and house, or worse you. Having the circuit wired according to code, with the correct breaker for the appropriate load is for a reason, not merely a suggestion. My neighbor got lucky this time and has learned a valuable lesson that cost him $300 and about six hours of time repairing and cleaning up. Not to mention his wife’s reaction and subsequent rant on being an idiot. (I left as this got too heated for me.)
For those more knowledgeable on this please add more warnings or better explanations. I know it is sometimes about cost but let’s be safe, cutting corners is not a good practice.
-- Live to tell the stories, they sound better that way.