Does a receptacle have to supply the max current that it is rated for?


Short answer:

Yes, in general it is safe to assume that an L5-30R will supply you up to 30A (nominal, 24A continuous) at ~120V. Give or take.

If you're still reading...

Suppose you come across a L5-30R (120V, 30A receptacle) somewhere. By spec, can you assume that there will be 30 amps at it?

The ratings of these outlets tells you about the safety limits of the outlet, not the actual characteristics of the supply.

Assuming that the supply is correctly configured - correct cabling, circuit breakers and so forth - then you can reasonably expect to be able to draw 30A from that outlet.

However there are a few factors that can limit your actual available current, most notably the impedance of the circuit from your outlet back to the point of supply.

The biggest impediment (if you will pardon the pun) to your maximum current draw may be the impedance of the supply circuit. The higher the impedance of the supply circuit the larger the...

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Then divide the power by the load per receptacle
For 20-amp circuit:

Maximum allowable number of receptacles = 2400 VA / 180 VA = 13.3

For 15-amp circuit:

Maximum allowable number of receptacles = 1800 VA / 180 VA = 10


A 120-volt, 20-amp circuit can supply 13 receptacles.

A 120-volt, 15-amp circuit can supply 10 receptacles.

6- The Minimum number of receptacle branch circuits for bank or office buildings

As per NEC section 220.14(J), if the number of receptacles is unknown so for bank and office buildings, we can calculate the receptacles load by multiplying the area in ft2 by the unit value (1 VA/ft2).

To get the required number of receptacle branch circuits for bank or office buildings make the following steps:

Step#1: Calculate the total receptacles load for the whole building as explained above. Step#2: Calculate the total receptacle circuit load in VA by multiplying its voltage by its amperage as...
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The wiring inside a dwelling that you cannot see may be an arc fault waiting to happen, due to improper installation; corrosion; damage caused by rodents, insects, or other pests; penetration by screws or nails after construction; or other problems. The arc-fault circuit interrupter (AFCI) helps prevent an arcing fault from becoming a fire. Unlike the ground-fault circuit interrupter (GFCI), the AFCI doesn’t provide personnel protection from electrical shocks, but it is designed to monitor a circuit for electrical current waveform characteristics that indicate an arcing fault.

AFCIs installed after Jan. 1, 2008, are required to be of the combination type, which includes technology to expand protection against parallel arcing faults as well as series arcing faults. AFCI devices used prior to 2008 were of the branch/feeder type, which offered less protection against parallel arcing faults.

The NEC requires AFCI protection in:

You can omit AFCI protection,...

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Structure of a Residential 15-Amp Duplex Receptacle

It is not necessary for a receptacle to have something plugged into it for it to cause a fire. The reason that there are two screw terminals on each bus is so that power can be supply to another receptacle or device. Hence, electrical current may be passing through the receptacle even though it has nothing plugged into it.

Stab-in / Push-in connections were common in the 1970's and 1980's. In 1996, UL Standard 498 was revised to only permit stab-in (push-in) connections with solid copper conductors that were size AWG #14. The manufactures reduced the size of the holes so that AWG #12 wire would not fit. AWG #12 wire is thicker and more stiff than AWG #14 wire. When the receptacle was pushed into the outlet box, too much pressure was being inserted on the spring metal gripper, and this was causing loose connections.

On duplex receptacles, there is a break tap between...

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Post 59

My company has just received a machine that we were told could be plugged into a 13amp 240v ring main,the machine has a rating of 13.9 amps on its serial plate,

Do we need to install a 16amp circuit and socket or is our supplier correct?

Post 58

What happens if my adapter with a rating of 12 volts 2amps is connected to a device with an input rating of 12v and 1.8 amps? Will this damage the device?

Post 57

I am swapping out a 1/2 hp general dewatering pump with a 1hp general dewatering pump. They are both 115v but the smaller one is 6 full load amps. While the new one is 14 full load amp. Can the new pump be wired the same as the old pump or do i need to do something different?

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Is the connections we are making, bad for our devices?
A mistake like this can cost you a lot of money.
A GPU is a “Graphics Processing Unit”, it is located in the video card. A CPU is a “Central Processing Unit”, it is located on the main board. I, at one time had a lot of questions about there power connectors, their current rating, the cross compatibility, jumper wires and unorthodox looking configurations, and what adaptors are safe to use. I did a lot of research and found conflicting answers. I looked at how reputable the source was, and how often I saw other reputable sources give the same answer. Being an electrical technician with 35 years experience, I myself, have a good working knowledge of this subject. I pooled of this information into one easy to understand writing, then made an illustration to go with it. The purpose of this article is to save you a lot of research time, and turn you into an expert by giving you good reliable information.

The white...

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210-21(b) Receptacles

A “Receptacle,” as defined in Article 100, is a contact device installed at an outlet for the connection of an attachment plug. The words “receptacle” and “receptacles” appear quite often in the National Electrical Code (NEC).

In fact, they appear more than 250 times. Although receptacles are manufactured in a wide variety of configurations and sizes, usually the first thing that comes to mind when we think of a receptacle is a 15-or 20-ampere, 125-volt duplex receptacle. Although it is a single device, it is not considered a single receptacle.

Article 100’s definition of a receptacle also states that a single receptacle is a single contact device with no other contact device on the same yoke. A multiple receptacle is two or more contact devices on the same yoke. Since a duplex receptacle contains two contact devices, it is a multiple receptacle, not a single one.

Receptacles installed on 15- and 20-ampere branch circuits must be of...

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Thanks for the replies Steve.

1) The electrical engineer needs to review and understand the various NEC articles. Have the EE refer to the following articles in the 2011 NEC. Exact verbiage taken directly from the 2011 NEC as shown below:

Article 406.3 Receptacle Rating and Type

(A) Receptacles: Receptacles shall be listed and marked with the manufacturers name or identification and voltage and ampere ratings.

Fine Note Print under this article:

The intent of 406.3(A) is to ensure that the receptacle is suitable for the branch circuit voltage and the load current that the receptacle must conduct.

2) Shown below is a NEMA rating chart for the various receptacles and plug configurations. Why are there 2 different NEMA voltage ratings then for 3-phase 30 amp receptacles?

3) Article 100 defines the definition of "Listed".

3A) Article 100 defines the definition of "Voltage"

4) Article 110.4 Voltages (exact verbiage...

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One book that should probably never be written is Power Distro for Dummies. Given the high voltages in play where power distribution is concerned and the danger of physical harm, it’d be a better idea if dummies stayed out of the electrical room and left electrical work to licensed electricians. However, there are certain things about power that audio people need to know, and though we do not suggest that you attempt adding a new circuit breaker box to a venue unless you are a licensed electrician, it might make your life easier if you knew a bit regarding power distro requirements.

How Much Is Enough?

Let’s start with a basic question that can easily and safely be answered on paper: How much power does my audio gear need? It’s a fair question and you’ll need the answer whether you are traveling with a P.A. or spec’ing a system for a new venue.

Power is expressed in watts. Typically the power requirements of an electrical device can be found on its rear panel...

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You are safe.

All you're taking about doing is plugging a 120V device into a 120V circuit, using a plug adapter you can purchase off the shelf.

For anything beyond this, consult a local licensed electrician.

If this wasn't safe, you couldn't just buy the adapters off the shelf. But you can buy these kinds of adapters:

Your UPS isn't going to draw any more current through a 30A breaker than it does through a 15A or 20A breaker.

All of your circuit breakers are clamped directly onto the fat aluminum buses in your service panel and subpanel(s), which are in turn directly connected to the fat cables that connect directly to the windings on the step-down transformer coil on the pole outside your home or office.

All the devices you plug into the wall, from a tiny 5 watt light bulb to your phone charger to your dishwasher, are directly connected to that transformer outside (which is directly connected to the high voltage power distribution...

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It doesn't matter, at all, what physical mediums are involved. You could solder two bits of wire to a fork and complete the circuit. That's the part you don't seem to be following. It doesn't matter that the power going to a downstream load is passing thru a busbar on a device. That particular bit of copper is used as part of the circuit just like every other bit of copper in the wires.

As Greg described (eloquently) "In series" and "In parallel" describe the path power takes when flowing to loads.

Serial is rarely, if ever, done. I can think of scant few examples of it in the real world. One that comes to mind is cheapo Christmas lights. You unplug one bulb and the 20 others in series go out. Another is when you want to use car speakers (4 ohm) in a household stereo (8 ohm)... Speaker guru's would take two car speakers and wire them in series... (into one speaker on the black tab, out the red tab, then directly to the black tab of the next, then out the red...

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Sales Customer Service FAQ's

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Applications and Design FAQ's

What is the current rating for Mill-Max male printed circuit pins? What is the largest acceptance range for the Mill-Max female receptacles? Can a pins/receptacles be supplied on Tape & Reel? Does Mill-Max cross to stamped and formed parts? Does Mill-Max provide any suggestions for press-fitting, footprints, etc.? Which press-fit feature is best suited for my application? Does Mill-Max offer non-magnetic parts? Can Mill-Max provide tighter tolerances than what is...
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Questions - Quick 220 Voltage Converter

How does the Quick 220 Power Supply work?

The Quick 220 Power Supply technically uses the fact that 220 / 240 volts AC is supplied to most facilities. The 220 / 240 volts is divided into 110/120 volt circuits for distribution within the building. Using standard 110 / 120 volt outlets and the Quick 220, the user can quickly identify and connect to the separated 110 / 120 volt halves of the original 220 / 240, restoring the 220/240 volt AC option without adding new electrical circuits or wiring to the building.

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How do I use the Quick 220 Power Supply?

First, connect one of the Quick 220 Power Supply cords to a standard 110 / 120 volt outlet.

Next, connect the second power cord from the Quick 220 Power Supply to an independent 110 / 120 volt outlet, using an extension cord if necessary. The "220-240 VOLTS" lamp will...

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