Summary:
Electrical Circuits Question: I have a 200A main panel which is fully utilized. I recently put in an in ground swimming pool and a finished basement - so I put in a main lug 20 circuit 100A panel downstream to service my pool and basement.
Check Out What Others Are Sharing at Ask the Electrician: Fine- very good. Ray from Bridgeport, Connecticut
I have a 200A main panel which is fully utilized. I recently put in an in ground swimming pool and a finished basement - so I put in a main lug 20 circuit 100A panel downstream to service my pool and basement.
Everything went all right until recently my 200A main breaker occasionally trips . This happened tonight when both central air units were on, (one -4 ton unit one 2 ton unit) my pool pump 15A and my washing machine.
I went to the main panel and measured 19A off one leg and 45 off the other. I may try load balancing and move the 4 ton unit to the leg drawing 19A - but I can't understand why this would trip a 200A main?
Mike.
Hi Mike - Great Electrical Repair Question! Mike - keep in mind that the starting amps of any motor is quite high. This is commonly called Lock Rotor Amps LRA and will be found on the A/C Unit Label Information. If both A/C units start at the same time and there is a moderate load in the home you may trip your main breaker. So how can you solve this? One option is to have a Time Delay Relay installed on one of the A/C units as to prevent both units from starting at the same time. The relay can be installed on the thermostat control voltage side of the circuit. You mentioned that you may try to balance the load of the A/C units, however they are most likely 240 Volts and should themselves be balanced. You can balance the panel loads by repositioning the higher 120 Volt loads onto the low reading buss. Let me know how it works out.
Dave
Thanks for your quick response on this holiday weekend - you are correct both AC units are running on 240V and by default are load balanced - its been a long week. The LRA on the 4 ton unit is 105 and the LRA on the 2 ton unit is 55. The 4 ton units's compressor outside shows a min fuse rating of 29A and a max of 50A - I was surprised to see that the 30A breaker that the 4 ton unit is on has never tripped. I thought I may have needed a new 200A main or maybe the terminals on it were loose. I guess if both units fire at the same time and my pool pump, well and other appliances are on at the same time I will have a potential problem. As for the time delay relay what manufacturer/rating would you recommend? I will also look at moving some of the higher 120V circuits, but the time delay relay sounds like a real fix.
Thank you!
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Skill Level:
Intermediate to Advanced - Electrical Repairs and Circuit Wiring is Best Performed by a Licensed Electrical Contractor.
Tools Required:
Basic Electricians Pouch of Hand Tools, a Voltage Tester and a Multi Meter.
Estimated Time:
Depends on personal level experience, ability to work with tools, work with electrical wiring, and the available access to the project area. Precaution:
Identify the project circuit, turn it OFF and Tag it with a Note before working with the wiring.
Important:
Modifying existing electrical circuits or installing additional electrical wiring should be done according to local and national electrical codes with a permit and be inspected.
This is a testing tool that is a Non-contact tester that I use to easily Detect Voltage in Cables, Cords, Circuit Breakers, Lighting Fixtures, Switches, Outlets and Wires. Simply insert the end of the tester into an outlet, lamp socket, or hold the end of the tester against the wire you wish to test. Very handy and easy to use.
This is great to troubleshoot a problem with outlet circuit wiring, is also used by most inspectors to test for power and check the polarity of circuit wiring.
It detects probable improper wiring conditions in standard 110-125 VAC outlets
Provides 6 probable wiring conditions that are quick and easy to read for ultimate efficiency
Lights indicate if wiring is correct and indicator light chart is included
Tests standard 3-wire outlets UL Listed Light indicates if wiring is incorrect, Very handy and easy to use.
A wire stripping tool used to safely strip electrical wires.
This handy tool has multiple uses:
The wire gauges are shown on the side of the tool so you know which slot to use for stripping insulation.
The end of the tool can be used to grip and bend wire which is handy for attaching wire onto the screw terminals of switches and outlets.
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