fisherelectric
01-05-2009, 01:29 PM
Got called to a house remodel job today where the GC said the furnace disconnect was "throwing sparks" and the heat wasn't working. Found a heat pump system with 20 kw back-up heat in the air handler. The original ('70s) furnace circuit was #2 Al sec w/ 100amp OCP run to a Zinsco 125amp 8/16 mlo load center. Then (I assume) 2 50 amp breakers feeding 2 pieces of #6Cu sec run to the furnace. One piece of #6 was burned up on the ends, the breaker was missing and it was curled up in the load center. The other #6 was on a 50amp breaker that was smoked. The bus bar where the both breakers had been was badly burnt. The hex screws were missing from the main lug terminations so the #2 sec had been arcing in the lugs with the furnace load. In addition, 2 120v circuits had been added to this loadcenter with no neutral present, using the sec ground to make them work. It looked like it had been that way for a long time.
I told the GC the whole mess needed to be replaced with 2 new circuits from the service and 2 new 60 amp disconnects and run new circuits for the 120volt loads. My question is was the original install compliant... the 125a MLO with 2 breakers feeding the furnace as disconnects, leaving space for hacks to add circuits with no neutral present or should it have had 2 disconnects to begin with? The furnace calls for 2 60amp circuits (MOP) and has supplementary breakers factory installed. Under the '05 here.
I told the GC the whole mess needed to be replaced with 2 new circuits from the service and 2 new 60 amp disconnects and run new circuits for the 120volt loads. My question is was the original install compliant... the 125a MLO with 2 breakers feeding the furnace as disconnects, leaving space for hacks to add circuits with no neutral present or should it have had 2 disconnects to begin with? The furnace calls for 2 60amp circuits (MOP) and has supplementary breakers factory installed. Under the '05 here.