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Are both sides of double breaker 30 amp or each of them 15 amp ?
Tech support optionsResource: safe electric wiring
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Are both sides of double breaker 30 amp or each of them 15 amp ?Tech support optionsResource: safe electric wiring |
| Use only 600 volt wire. Lamp cord, extension cords are not rated 600 volt. Use copper wire only. Aluminum wire is fire risk and should be avoided or installed by professional. 30 amp breaker use 10 gauge / 120-240 volt 30 amp outlet can be installed on 30 amp breaker only/ use 10 gauge wire ... cannot be connected to 15-20-40 amp breaker.  Orange/ #10 gauge wire, with ground ... 30 amp capacity. Safe maximum: 30 x 80% = 24 amps. Buy: 10-2 gauge/ 30 amp 10-3/ 30 amp Southwire electric tools |
Yellow
12 gauge 20 amp 120 volt 20 amp outlet can be installed on 20 amp breaker, but not 15 amp breaker/ use 12 ga wire. ... cannot be connected to 30-40 amp breaker. 1  Yellow/ #12 gauge wire, with ground ... 20 amp capacity. Safe maximum 16 amps. Buy: 12-2 gauge/ 20 amp 12-3/ 20 amp NMB is house wiring UF is underground Rolls of stranded wire HOOK UP Wires |
White
14 gauge 15 amp 120 volt 15 amp outlet, AFCI, GFCI, timer, switch etc can be installed on 15 or 20 amp breaker. Never connect 15 gauge wire to 20-30-40 amp breaker.  White/ #14 gauge wire, with ground ... 15 amp capacity. Safe maximum 12 amps. Buy: 14-2 gauge/ 15 amp 14-3/ 15 amp NMB is house wiring UF is underground |
 Electrical tools must be insulated. Always best to disconnect power, but insulation failure, lack of proper grounding, grounded neutral, lack of GFCI, out-of-code wiring, generator operating without transfer switch, and other problems still pose a risk to anyone working on electric power ... even when breaker is off. Buy: Electrician tools kits KLEIN TOOLS Tools kits IRWIN tools KNIPEX Telephone cable knife Low Voltage Mounting Bracket for Telephone |
 Multimeters Voltage is tested across two separate wires. Ohms or resistance is tested across both ends of same wire. Amperage is tested along one or two points on same wire. Buy: Analog multimeter Multimeters at Amazon Klein multimeter Electric testers at Amazon Clampmeter for testing amp flow on line |
 Electrically insulated tools When removing insulation from wire, do NOT score or put cuts on surface of copper wire. Doing so increases resistance and heat on wire and creates possible weak point. Buy tools: KLEIN TOOLS Wire strippers at Amazon Electric Wire Stripping Machine Linesman pliers Utility knife at Amazon |
 Question:
Are both sides of double breaker 30 amp or 15 amp ?Answer: Both are 30 amp You can use a double breaker as two single breakers to supply 120 volt to two separate circuits.. If you have a 30 amp double breaker, you can connect a single 10 gauge hot wire and it will work for 120 volt. You would NOT connect a 12 or 14 gauge wire to the 30 amp breaker or it creates a fire hazard. You can create a 240 breaker by combining 2 single-pole breakers, they must be located side-by-side, and code requires a 'common bar' between the breaker switches so if one trips, then the other breaker also trips. You would NOT use two 15 amp breakers. You would use two 30 amp breakers and 10 gauge wire. Calculations Volts x Amps = Watts is a basic electrical formula Volts (V or E) x amps (A or I) = watts (P or power) -Let's calculate watts for 120 volt single breaker -15 amp single breaker. 120 volts x 15 amps = 1800 watts of power -30 amp single breaker. 120 volts x 30 amps = 3600 watts of power. -Calculate watts for 240 volt double breaker. -15 amp double breaker. 240 volts x 15 amps = 3600 watts of power -30 amp double breaker. 240 volts x 30 amps = 7200 watts of power. With 240 volt, the watts or power is doubled .... Amps are not cut in half Since each leg of 240 volt circuit offers 120 volt potential to ground, then you're getting two legs of out-of-phase 120 volt when you use double breaker, and doing so doubles the voltage and doubles the watts (power), it does not halve the amps. This shows that each leg of 30 amp double breaker delivers 30 amps, and not 15 amps. . |
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| Mr
Laing emailed a question. He asked, Since each side of 30 amp double breaker is 30 amps, is the total 60 amps? The answer is no Maximum 30 amps can flow on each side (or leg) of a 30 amp double breaker, but because it's alternating current, the current of amperage reverses direction 60 times per second, and the same 30 amps that are flowing IN on the first leg are flowing back OUT on the second leg, at the same time .. then the alternating current reverses direction, and same 30 amps flows back in on the second leg and out the first leg. And because its the same amps, you cannot add them together, so it's never 60 amps. To begin, each single-phase circuit requires 2 wires to complete the circuit. The 30 amp double breaker has 2 wires, and each wire is called a leg. Amperage is a numerical value for the number of electrons that move back n forth between each leg.... so if the load is drawing 30 amps, then 30 amps worth of electrons are flowing IN on the first leg and back OUT on the second leg .... and the movement of electrons passing through the load, is what energizes the load. Because of how the generator produces AC electricity, the current of electrons is constantly changing direction. 60 times per second, the electrons slow down and come to a brief halt, and .... then start moving the reverse direction ... traveling in and out on each leg of the breaker ... and it's all the same electrons flowing through both legs of the breaker, going back-and-forth, one direction then the other. Because the breaker maximum only allows 30 amps worth of electrons, then if more electrons are present, the breaker trips. At no point are 60 amps allowed to flow through a 30 amp breaker. Read how a generator works |
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 If a 30 amp double pole breaker was 15 amps on each leg, then a 20 amp double breaker would be 10 amps on each leg. And a 15 amp double breaker would be 7.5 amps on each leg. There is no 10 amp circuit breaker or 7.5 amp breaker made for residential breaker box. There are 5-10 amp fuses etc made for various applications, such as a line fuse for automotive or 12 volt DC breaker for boats. |
| Amperage and heat The breaker responds to amperage, not voltage. The breaker does not respond to ordinary household voltage spikes, for example when a motor starts, but a breaker can trip if direct lightning strike energizes the wire with enough voltage. For voltage spikes caused by nearby lightning strike, motor start-up etc, a surge protector is used. Resource: How to wire whole house surge Household circuit breakers are designed with thermal and magnetic properties that respond to different overcurrent conditions. Overcurrent means too much current, and since current is the flow of electrons on the wire, then overcurrent means too many electrons are getting pushed down the wire by the force of voltage. The thermal
(heat) mechanism located inside breaker expands in response to
temperature and
is calibrated to trip when current exceeds breaker rating. Thermal
protection is designed to respond slowly (not instantly). This
allows overcurrent to exceed breaker rating for a moment so when a
motor start-up pulls a surge of amps, then the breaker does not trip.
Thermal protection will also trip if there is a loose wire or
connection that causes heat to exceed breaker rating.
The magnetic protection is for emergency conditions such as short circuit or faults where the amount of current surpasses normal amp flow on the line. The surge of electrons passes through a coil of wire located inside the breaker, which creates a strong magnetic field, causing the breaker to trip 'instantly.' Thermal and magnetic protection means the household breaker is designed to trip 'instantly' when a short circuit occurs, but delays an appropriate amount of time before tripping when a circuit briefly draws too many amps. If there is a short circuit (insulation failure), where electrons (amps) start running wildly into the ground wire (assuming installation is correctly grounded), then wires and devices etc can melt before the breaker trips. Why you need ground wire Read about heat on the wire |
| Question: Can I connect 120 volt 30 amp single-pole load to 30 amp double breaker? Answer: Yes. 30 amp requires 10 gauge wire. Always use solid copper wire, and make connections very tight. Question: Can I connect 120 volt 15 amp circuit to 30 amp double breaker. Answer: Generally no. 30 amp breakers are made for 30 amp loads only. You can use smaller 14 gauge wire if and only if you install 15 amp line fuse, or surface mount breaker, or din rail mounted breaker on the 14 ga wire. Multiple overcurrent protection (breaker, fuse) on a circuit is ok. The fuse or breaker must be inside a box or subpanel with cover, and must be easily accessible and not concealed inside a wall. The fuse can be installed at the load or anywhere on the line and still protect entire length of wire. Resource: Fuseholders The best solution is always connect to correct size breaker, or install tandem breaker if panel does not have enough spaces. Not enough space in breaker box Question: My circuit breakers are 20 amp, but lights switches, outlet and the wall timer are rated for 15 amp? Is this safe? Answer: Yes. It is code to install 15 amp switch, outlet, dimmer, timer etc on a 20 amp breaker. However if breaker is 15 amp, then only 15 amp switches and outlets, gfci etc are permitted. Ratings for each device are embossed into the device. Of course if the outlet or switch supply power to 120 volt 1-Hp pool pump that draws 16 amp, then you want a 20 amp switch or outlet. Each device has a rating for volts and amps. Add up total wattage being controlled by the switch etc, and divide by 120 volts to calculate amp draw of load. Question: Isn't electricity 110 volt and 220 volt? Your website says 120 and 240. Answer: 120-240 is correct. Check the rating label on each appliance, TV, etc. and it often shows 115 or 125 volts. Electric water heaters show 240 volt. Electric device manufacturer's spec sheets show 120-240. Switches and outlet and timer manuals show 120-240. Look at switch or outlet, and the 120-240 volt rating will be embossed somewhere on the device. Switches rated for 120 can only be used on 120 volt circuits. Switches rated for 120-277V can be used for 120 and 240V, and used for commercial 208, 277 volt. Switches rated for 240V always have 4 screws, and are double-pole, and can be used for 120, 208, 240, but not 277 volt. Resources: What is 208 volt What is 277 volt  Actual
voltages at each location vary. Folks have emailed saying they test 250
volt, and their grid supplier says it's 'normal.' My home measures 236
volts most times. And 122 volt on the 120 volt lines.Anything greater or less than 80% rated value can damage inductive loads like motors, while resistance loads like incandescent light bulbs just get brighter or dimmer. Buy: Kilowatt hour meter Resources: Fuseholders Not enough space in breaker box See inside main breaker box Basic household wiring diagrams Why ground wire is needed How to wire switches |
| Question: Isn't a 30 amp double pole breaker is same as two 30 amp single pole breakers stuck together, so I can put 30 amps on each leg? Answer: Yes, because the breaker draws 30 amps from each leg ... 1 leg per each busbar. You might be better using two individual 30 amp breakers since a double breaker has a connection bar and both sides will trip if either leg trips. Question: Can I use 10 gauge wire on a 20 amp breaker. Answer: Yes as long as the large wire fits each device (outlet, switch etc) and the connections can fit inside your junction boxes. It is possible that a larger wire will run cooler and save energy, especially if distances are greater than 50-100'. Question: If you load a panel up with only single pole breakers can you put 200 amps on each leg? Answer: No. A main breaker panel has 2 hot busbars (legs), with each busbar receiving power from a different end of the Secondary coil on the transformer. A main breaker is a large-amperage double breaker, same as any double breaker in the breaker box, except it supplies power to each busbar. So your question is like asking if you can draw 60 amps off a 30 amp double breaker ... the answer is NO. Why? Each leg on the 30 amp breaker delivers max 30 amp. One or the other leg on the 30 amp breaker will trip at 30 amp, and cause other leg to trip also. This means the 30 amp double breaker has max 30 amp rating. Same with 200 amp main breaker ... 200 amps on each leg would be 400 total amps. If you draw 400 Amps, the main breaker will trip ... because the 200 Amp main breaker has a limit of 200 amps. So a 120/240Volt panel with a 200 amp main breaker has maximum 200 Amp rating, no matter if loads are 120Volts or 240Volts.  Note, breakers are generally not fast-acting. They allow a certain amount of over-amps before the heat causes breaker to trip, which means actual amperage can exceed the breaker's amp rating. However, chronically overclocking breakers will cause the breaker and busbar to get warm or hot, then cool off when no power is being used, and then get warm or hot again as power is used again. Over time, this causes busbar to get soft and start arcing with the breaker ... and will eventually destroy that tab on the busbar, and ruining breaker. Breakers should not be warm or hot. Use hand to test if breakers are running hot when under load.  Overheated main breaker can cause permanent damage to the busbar ... destroying the breaker box. If individual breaker is overheating and melts 1 busbar tab, then a new breaker can be moved to another slot, and panel is not destroyed. Keep loads within the safe maximum for each breaker. The safe maximum calculation is 80%. If breaker is rated 30 amp, then 30 x .8 = 24 amp safe maximum. 200 amp main breaker x .8 = 160 amp safe maximum. Add up wattage of loads on each breaker, and divide by voltage to get amperage at full load. Add up total amperage on all breakers to determine if electric service provides enough amps. Using this guideline will prevent long term issues and help protect investment. Do the main breaker stress test  Question:Can I put 190 amps on one leg, and 5 amps on another leg? Answer: No. This can cause imbalance issues in the transformer. It would be difficult to accidentally put 190 amps on one leg and 5 on the other. Why? When a double breaker is stabbed into the panel, it draws a Hot from each busbar because every other breaker slot goes to a different leg on the busbar. So all double breakers are automatically balanced, and draw equally from both busbars. Single breaker: If you put all the single breakers on one side of the panel, every other breaker will draw from a separate busbar and so the load is balanced. This assumes you don't install 15 amp breaker every other slot, and 30 amp on the other slots ... because that would draw unevenly from both busbars. Ideally in a residential breaker panel, single breakers should be evenly divided, with roughly half on one side and half on the other. The double breakers are snapped over both busbars so their location is unimportant for 'balancing the loads.' Leave top two breaker spaces, located closest to main breaker, on either side of panel for installing Type 1-2 surge protection device. Type 1-2-3 surge protectors If the residential breaker panel is somehow unbalanced, this can cause damage to motors, HVAC etc. The problem of imbalance is usually found in commercial 3-phase installations where 'voltage monitors' are used to protect vulnerable circuits from imbalance issues. A voltage monitor can protect household HVAC from low voltage or brownout events. How to wire voltage monitor More info: Residential breaker box has 2 Hot busbars. Each busbar is 'out-of-phase' from the other busbar. Each busbar has 120 volt potential to Neutral (phase voltage) and 240 volt potential to the other busbar (line voltage). 240 volt breaker snaps over both Hot busbars, while single-pole breaker snaps over one Hot busbar. The breaker box should not be overloaded on one busbar, or one leg. Unbalanced load can unbalance the transformer and electricity might not have the correct waveform, causing damage to motors, electronics etc. Resource: What does out-of-phase mean Troubleshoot household electric See inside main breaker box Basic household wiring diagrams |
| Question: Can I reverse feed a circuit breaker and have it work? Answer: Yes, most molded-case circuit breakers can be reverse fed and they work fine. However, if the circuit breaker has LINE and LOAD embossed or printed on each end of breaker, then it cannot be reverse fed. Resource: Reverse feed breakers .pdf |
 Larger image Refer to chart above. 1500 watt element. 12.5 amp @ 120 volt or 6.3 amp @ 240 volt So the amp rating drops by 1/2 for same wattage load. This means that 240 volt breakers are designed to handle large appliances that cannot be supplied by 120 volt. To illustrate how much more power 240 volt supplies to an appliance, we use the 4500 watt element with a rating of 240 volt. When connected to 240 volts 30 amp double breaker, the element heats 16+ gallons per hour. When same rated element is connected to 120 volt, it heats 1/4 the amount of water per hour, and a smaller breaker can be used. Resources: Figure volts amps watts Formulas for ohm's law Match breaker and wire size |
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