q2l 125 a breaker

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stew

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federal way,washington
I have an Olive Garden with a hot water booster on the dish machine. All of thier locations are the same. They feed these with a 125 a q2l sq d breaker. the continious load on this system is 119-120 amps. They have had breaker tripping problems at this particular location. Is the breaker not the right type or is thier a square d continuous type?
 
stew said:
I have an Olive Garden with a hot water booster on the dish machine. All of thier locations are the same. They feed these with a 125 a q2l sq d breaker. the continious load on this system is 119-120 amps. They have had breaker tripping problems at this particular location. Is the breaker not the right type or is thier a square d continuous type?
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For a continuous load you should have a Q2L 150A breaker and conductors. There is no 'continuous' (I am sure you meant a 100%) rated breaker that will interchange with your Q2L.
 
Long shot here, but maybe it's the placement of the breaker in the gear. It may be it's gaining volunteer heat from breakers below it, sending it over it's thermal trip limit.
 
This breaker trips because of heat or magnetic forces. The magnetic forces are caused by currents in excess of about 6x FLA, which is not a problem you describe. This leaves heat as the area to investigate.

Breaker heating is caused by current flowing through the breaker or by the air around the breaker (the ambient). If the air around the breaker is below 40?C (140?F) the breaker can actually carry more current than it can above 40?C. So if the upstream breaker is in a cooler environment, like air conditioning, it very well could carry more current than if it is in an enclosure with other heat producing items, like other breakers.

To account for the heat produced by current flowing through a breaker, when it is installed in an enclosure, with an internal temperature of 40?C, it should not be loaded to more than 80% (in your case 100A). Yes, it is possible to load the breaker past this point but eventually it will heat up and trip, unless sufficient cooling time has been provided. For example: loading the breaker to 120A for 8 hours may require a cooling period of 16hrs; everything really depends on the ambient conditions.
 
the amperage is a measured current. the current actually is 119,115,114. The main breaker is located about 40 ft away in an mdp panel with I line breakers. that area would be somewhat cooler inasmuch as it is not in the area of the dish machine. The breaker in question is in a single breaker enclosure. The electrician before me replaced the original breaker and has since replaced the replacement breaker. One caveat to this is that the breaker now in place is not a new unit. I dont know if he just put the old one back in or got a used one and put it in. He has however charge the customer for both. They dont seem real happy when i showed them that the breaker now in place is obviously not new. Bet they dont use this guy again. I am going to see if I can get some heater elements of the next smaller size to reduce the current a bit if possible without sacrificing too much heater performance.
 
if there is a 125a breaker in the I-line panel that feeds this one, then why do you even need it? Can you just replace the whole thing with a disconnect switch and call it a day?
 
stew said:
the amperage is a measured current. the current actually is 119,115,114. The main breaker is located about 40 ft away in an mdp panel with I line breakers. that area would be somewhat cooler inasmuch as it is not in the area of the dish machine. The breaker in question is in a single breaker enclosure. The electrician before me replaced the original breaker and has since replaced the replacement breaker. One caveat to this is that the breaker now in place is not a new unit. I dont know if he just put the old one back in or got a used one and put it in. He has however charge the customer for both. They dont seem real happy when i showed them that the breaker now in place is obviously not new. Bet they dont use this guy again. I am going to see if I can get some heater elements of the next smaller size to reduce the current a bit if possible without sacrificing too much heater performance.
Click to expand...

Q2L breakers are no longer produced by Square D. They were obsoleted more than several (+5?) years ago.
 
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