Questions tagged [ampacity]

A portmanteau combining the words for Amperage and Capacity. Defined as the maximum current (Amperage) that a device or conductor can carry without sustaining immediate or progressive deterioration. Defined in some electrical codes.

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91 views

Why would this power mosfet be made in a surface mount package?

I’m looking at the CSD17303Q5 power mosfet which boasts a 100A max drain current. It confuses me why they have it in a VSON surface mount package because most pcbs would not be able to handle that ...
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5answers
151 views

Derating ampacity of a wire if it is stranded?

Do I need to derate a wire if it is stranded? Or will a #12 wire have the same ampacity whether or not it is stranded? Is this affected at all by AC versus DC?
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49 views

Battery connector and wire ampacity

I’m considering using a JST ACH connector with my LiPo, but I don’t understand whether the current rating on the data sheet is for aggregate or for each wire individually (which is my guess since they ...
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4answers
798 views

Ampacity of Conductive Tape

How do I measure ampacity of conductive tape? I want to replace a wired battery to equipment connection with copper adhesive tape because I need a very low profile on the connection. The maximum ...
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1answer
83 views

Are rated cable ampacities per conductor or per circuit?

I'd like to construct a cable using connectors DigiKey 708-1190-ND to connect a 20A LED to its power supply. The connector is rated "32A". In this example the connector's third pin will not be ...
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1answer
102 views

120 Watts and 7.2 Volts, how many Amps?

For a project I need to switch on a simple handheld vacuum cleaner with an Arduino. I am thinking of using a relay or mosfet. I opened the case and a 7.4 V 2200 mAh Li-Ion battery powers the motor, ...
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2answers
88 views

Ampacity Testing

Just a simple understanding question. If I obtained a DC bench power supply that has a current limit, could I test the ampacity of a wire by connecting said wire across the terminals? So when I slowly ...
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1answer
183 views

Proper supply wiring for CNC router 4.1 kW 3Φ motor and 120 V accessories?

I'm building a CNC router table that has a three-phase 220 V spindle motor, and 120 V computer (and accessories). The spindle's nameplate: As you can see it tops out at 20.3 A @ 220 V. The VFD’s (...
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2answers
604 views

Determining safe current and fuse rating for LV LED lighting

My home builder pre-pulled a length of 18-8 solid copper wire (18 AWG, 8 insulated conductors inside single jacket) into the ceiling of a room where I want to use some LED lighting with a remote power ...
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1answer
79 views

Suitable connector/wire for 3A output from PSU

I've searched through the questions that have been asked but none have dealt with this particular problem: I'm designing a PSU board that will have, among other things, a 12V/3A regulator. I want to ...
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1answer
46 views

PSU for Ampacity test of connection

i have this problem. I have to validate with a test that my connection on my power board can carry the nominal current required by the specs. For current around 10A the setup I'm using is a ...
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3answers
15k views

How to choose proper size of high power DC cable connections

I can't understand how to properly calculate AWG of a cable working in DC at high current: I found several tables for AC, but I don't know if/how they can be applied to DC. My system is rated 70V/...
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1k views

Magnet Wire Insulation

A close examination on magnet wire tables of various manufacturers like `http://www.epicos.com/EPCompanyProfileWeb/Content/CABLES/Magnet%20Wire%20Data%20Sheet.pdf (page 9),shows that the ratio of the ...
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5answers
8k views

Which wire gauge for a 250 amp source?

I have no real experience with this stuff... I have two 6V 220Ah DC golf cart batteries that I want to put in series to make a 12V 220Ah output that I will connect to a 3000W power inverter, my ...
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1answer
1k views

Calculate gauge of wire with voltage and current

I would like to figure out these two things: X gauge of wire needed dependent on the current needed, and the length. X max length of wire dependent on the current, and the gauge.
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1answer
1k views

Current capacity of copper wires in vacuum

I’d like to know the current carrying capacity of copper wires in vacuum. The current plan (NPI) calls for sending ~3 amps through the vacuum space of a cryostat. Has anyone done this? Have any ...
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3answers
15k views

Voltage Drop and Safe Current Load on CAT5 Cable

I am going to use this passive PoE injector cable set to power a Raspberry Pi model B. The Raspberry Pi model B consumes between 700mA-1000mA (mine will also be powering the RPi Camera Module). Using ...
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1answer
2k views

3 phase circuit, 3 x single-phase (hot-hot) loads: what ampacity?

I'm not an electrician (thus the question), but I'd like to know what is possible from a specification standpoint. Let's say we have a standard 3 phase power supply for a commercial building. We want ...
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2answers
629 views

Allowable ampacity through cable

For an application we are considering pulsing a current through a conductor. The conductor have an ampacity rating of 12.5A for continuous operation. During the pulse we get currents around 25A and ...
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1answer
3k views

Are there any rules of thumb when computing pulse current ratings for PCB traces?

Say I have a surface PCB trace, 4 oz, 50 mils. That trace should be able to carry around 15 amps continuous, according a calculator I'm using. (Obviously your trace ampacity estimates may vary with ...
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1answer
1k views

how to calculate thickness of copper conductor

Can you please explain how to calculate thickness of a copper conductor for the next task: I would like to use a DC power supply instead of some batteries for my sensors. So we have V volts and AH ...