XO Breaker

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Old 08-22-17, 03:33 PM
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XO Breaker

Hi, I know they are old but I had a Cutler Hammer XO240 Circuit Breaker go bad on me. I know the only ones I can get are used or refurbished. I want to leave it in and replace the circuit with a square D 2circuit sub panel box. I want to know if I throw the main, can I add #10 wire to he main lugs and run it into the new breaker box? I can't see any other way to do it. Any Suggestions?
 
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Old 08-22-17, 04:55 PM
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You can based on NEC tap rules. What is the size of the main breaker? What is the maximum load?

Feeder Tap Rules
10-Foot Feeder Tap Rule [240.21(B)(1)]
Feeder tap conductors can be run not over 10 ft without overcurrent protection at the point they receive their supply, but they must be installed in accordance with the following requirements: Figure 1
(1) The ampacity of the tap conductor is:
1 Not less than the computed load in accordance with Article 220, and
2 Not less than the rating of the device supplied by the tap conductors or the overcurrent protective device at the termination of the tap conductors.
(2) The tap conductors do not extend beyond the equipment they supply.
(3) The tap conductors are installed in a raceway if they leave the enclosure.
(4) The tap conductors have an ampacity of no less than 10 percent of the ampacity of the overcurrent protection device from which the conductors are tapped.

25-Foot Feeder Tap Rule [240.21(B)(2)
Feeder tap conductors can be run not over 25 ft without overcurrent protection at the point they receive their supply, but they must be installed in accordance with the following requirements: Figure 2
(1) The ampacity of the tap conductors is not less than 1/3 the ampacity of the overcurrent protection device protecting the feeder.
(2) The tap conductors terminate in a single circuit breaker, or set of fuses having a rating no greater than the conductor ampacity as listed in Table 310.16.
(3) The tap conductors are suitably protected from physical damage or are enclosed in a raceway.
 
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Old 08-22-17, 05:19 PM
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The lugs are only for one conductor . You cannot insert the #10 into a lug with another wire already in it.
 
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Old 08-22-17, 05:57 PM
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I thought he meant the lugs at the bottom of a combo main breaker/main lug panel. Maybe I misunderstood. Coachman, does your panel have a main breaker and lugs at the bottom?
 
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Old 08-22-17, 06:48 PM
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No, the main is a 100 amp throw switch with the main wire going through conduit to the bottom of the panel where it's connected. That's where I was going to tap it from but I guess that's a bad idea.
 
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Old 08-22-17, 07:32 PM
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Since the panel is obsolete I would recommend changing out the panel. Not the cheapest route but likely the best.
 
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Old 08-23-17, 08:53 AM
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Thank you everyone for all your comments and suggestions. I've decided to have it done right and be done with it. I'm going to put in a new Square D breaker box and eliminate all the old stuff...it's the best thing. Why fool with obsolete stuff. Again, THANK YOU and have a great day Joe
 
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Old 08-23-17, 06:28 PM
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I think that is a good choice!
 
 

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