How Can I Determine If I Have 100 Or 200 Amp Electric Service
The problem
It's a dark and stormy night. You flick on the hall lite, plug in the coffee maker and crank up the portable electrical heater. You're starting to experience comfortable, when you hear a faint, all the same ominous, click—and everything goes black. Information technology'southward not a cat burglar or a poltergeist playing tricks with your electrical system. It's an overloaded circuit being protected by a tripped electrical circuit breaker. Kinda spooky and mysterious, eh? Not if you know a few unproblematic things.
Figure A: A Properly Functioning 15-AMP Circuit
This circuit has wires and an electrical circuit breaker that tin can easily behave the amperage required by the devices
on information technology.
What's a excursion?
When electricity enters your home, it goes to a circuit billow box (or fuse box in older homes), where it's divided into a number of circuits. Each circuit is protected by a billow or fuse. Bedrooms, living rooms and family rooms where but lights, warning clocks and other small electrical items are usually used are normally on xv-amp circuits. Kitchens, laundry rooms, bathrooms and dining rooms—places where y'all're more than likely to use toasters, irons, hair dryers and other big-watt items—are commonly served by heavier-duty, 20-amp circuits. Major appliances like five,000-watt electric h2o heaters and ten,000-watt electric ranges need so much electricity that they take their ain 30- to fifty-amp defended circuit (Encounter Fig. D in "Boosted Information" below), protected past large, "double pole" circuit breaker sizes.
What's a excursion overload?
The circuit breaker, the wire and fifty-fifty the wire insulation are all designed to work equally a system—and that system has limits. Try to push more current through a excursion than it's designed for and things offset happening (Fig. B). Wires heat upwards under the burden of carrying the excess current. When this happens, the insulation around the wire can degrade or fifty-fifty melt. When insulation melts, current is no longer confined within the wire. That'south when fires beginning. Luckily, the circuit breaker senses the excess current and "trips" to cease the menstruation of power before impairment occurs.
On the nighttime the lights went out at your house, you were fine with only the lights and coffee maker operating. The real problem began when y'all plugged in that darn space heater.
Effigy B: An Overloaded Circuit
This circuit has too many energy-demanding devices on it and is trying to carry more amperage than it's designed for. Things begin to heat up. Luckily the circuit billow senses this, trips and "breaks" the circuit.
How to Summate Amps, Volts and Watts
To start solving the problem, we need to know i simple "rule of thumb" formula. This formula volition assist us determine if all the electrical stuff on a particular circuit is overloading it. This formula also helps ascertain some everyday terms and how they chronicle to i another. After all, light bulbs and space heaters are labeled in watts; tools and excursion breakers in amps; and our household electrical system in volts: How do they all fit together?
The uncomplicated formula (Fig. C) tells us how: Watts divided by voltage equals amps. The other equations shown are just other means of saying the aforementioned thing.
Voltage can most simply be described as the force per unit area under which electricity—a chain of electrons—moves. Most household electric current is pushed at 120 volts, though current to large electrical appliances is pushed at the higher pressure of 240 volts.
Amps (or amperes) is a measurement of the number of electrons the voltage pushes past a given point in
1 2d.
Watts is a unit of measurement for electrical power. Information technology indicates how many electrons were pushed through an electrical gadget to make it work. It's what the electric company bills yous for.
Figure C: The Basic Formula
Use these elementary equations to catechumen different measurements of electricity to help decide things like how many outlets on a fifteen amp breaker you can have or how many lights on a xv amp excursion you can accept.
Learn about tips for easier home electric wiring here.
Why Do Breakers Trip?
The circuit and circuit breaker that you tripped have a capacity of 15 amps, or 1,800 watts (15 amps x 120 volts = 1,800 watts). The lights drew 360 watts, or a beggarly 3 amps (360 watts divided past 120 volts = 3 amps)—well within the capacity of your 15-amp organisation. The 800-watt coffee maker (divided by 120 volts) drew six.six amps, substantially more power than the lights, simply their combined nine.6-amp draw is yet within the limits of the xv-amp circuit.
But when you plugged in the 1,200-watt space heater, the ten amps it required, plus the draw of the other 2 devices, pulled nineteen.6 amps through a 15-amp system (Fig. B). It's like a python swallowing a squealer; the system just can't handle the load. The circuit billow tolerated this for a while. Merely when the backlog current and resultant heat began deforming the ii pieces of metal inside the billow, they started "pulling the trigger." And when the metal pieces bent to a sure bespeak, the trigger snapped two contact points apart, interrupting the flow of electricity and shutting downwards that circuit. If there'due south a huge, sudden describe on a excursion, a little electromagnet in the excursion breaker can pull the contact points apart too. If y'all accept fuses, the excess estrus melts a wire inside the fuse, which in plough stops the flow of electricity.
If this had been a 20-amp breaker—1 with thicker, No. 12 wire that could carry 2,400 watts—the breaker wouldn't have tripped. But once the wire is in the wall and the breaker is in the breaker box, in that location's not much you can practice to upgrade an established circuit. But you do accept other choices.
240-Volt Circuits
Larger appliances, like electrical h2o heaters, dryers and stoves, crave and then much power that electricity is brought to them via 240-volt circuits. That'south because the voltage in 240-volt circuits "pushes" twice as hard. For example, a 6,000-watt electric flugelhorn on a 120-volt circuit would crave a 50-amp circuit (6,000 watts divided by 120 volts = 50 amps). That would require mammoth wires. Simply that same 6,000-watt flugelhorn on a 240-volt circuit requires only a 25-amp excursion (6,000 divided by 240 = 25) and a smaller wire and circuit billow.
Solution Ane — The Short Term Fix
The uncomplicated solution is to plug the space heater into an outlet on a circuit that has excess capacity. You can decide the existing load on a excursion fairly easily: Click off the circuit breaker, and so flick on light switches and examination outlets to see which ones no longer function. And so add together up the total watt load of devices on that excursion. This is often easier said than done. Sometimes a excursion labeled "bedroom" volition power outlets in the laundry room. Or the upper and lower outlets of a duplex receptacle will exist on different circuits. Once you accept a circuit mapped out and the electric loads added up, you'll be able to tell if you can plug more than devices into the circuit without overloading it.
Equally you add up the electrical loads, keep in mind that a wire rated at fifteen amps can carry 15 amps all twenty-four hour period long. Notwithstanding, 15-amp breakers and fuses can only bear 12 amps—80 pct of their rating—on a continuous basis. Continuous ground is considered to be a circuit loaded to capacity for 3 hours or more. This 80 percent rule applies to all breakers and fuses. For more in-depth information on calculating loads, see Preventing Electrical Overloads.
Solution Two — The Long Term Fix
The best long-term solution is to install a new defended circuit and outlet for the heater. Most electricians will suggest a dedicated circuit for any appliance that volition describe more than one-half the capacity of a circuit. Fig. D in "Additional Information" (below) shows the wattage of appliances that usually have defended circuits. Anytime you install a large electric appliance—whether it's 120 or 240 volts—install it on its own dedicated excursion with the right size wire and circuit breaker.
Equally you can come across from Fig. E, a 20-amp breaker with thicker, No. 12 wire can carry more current than a xv-amp circuit with No. 14 wire. When you lot're wiring or rewiring a kitchen, laundry room, bathroom or dining room, the National Electrical Code will crave y'all to install twenty-amp circuits, which tin bear more electric current. If you utilise a lot of power tools, it makes sense to use xx-amp circuits for your garage, workshop and basement also.
For information on how to wire a new excursion, see How to Connect a New Circuit.
Figure East: Wire Sizes
The larger 12-estimate wire tin safely carry more than amperage than the smaller 14-gauge wire—without overheating.
Larn almost the 8 most common electric lawmaking violations here.
No tampering allowed
Homeowners who put a "penny in the fuse box" to forestall fuses from blowing have brusk-circuited brains. Without a fuse to disrupt the menstruum of ability when too many amps are pushed through a circuit, wires overheat, wire insulation melts and fires intermission out. And you lot can't just supervene upon a 15-amp billow with a 20-amp breaker; that's the modern-mean solar day equivalent of putting a penny in the fuse box. Remember, the circuit breaker, wire and wire insulation are all designed and sized to work together—safely.
Additional Information
- Effigy D: Mutual Dedicated Circuits
Source: https://www.familyhandyman.com/article/how-circuit-breakers-work/
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