Type AC cable — why is it still made/used?


Old-style armored cable (Type AC) is still made and widely distributed. Why is this, given that type MC cable is more versatile (more conductor configurations, more Code-permitted applications) than type AC cable by far, and the new type MCI-A products coming out eliminate any edge AC may have had in termination labor? I'd have thought type AC would be utterly obsolete now, replaced in all new work and rework by type MC. Are there applications where AC can be used but MC (especially MCI-A) can't?

(For those who haven't kept up -- MCI-A is a type of MC cable that uses a bonding means consisting of a full sized aluminum ground wire integral with the corrugated, spiral wrapped armor, usually aluminum as well. It is available through multiple manufacturers -- Encore calls it SmartGround or MC-SG, Atkore/AFC calls it MC-Quik, and Southwire calls it...

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The size of the cables isn't due to the size of the copper conductor inside them - that's a fairly small part of the cable. Most of the bulk comes from the electrical insulation.

Electrical cable needs to be insulated so it doesn't short circuit. The higher the voltage, the thicker the insulation required.

Your thick mains power cord is insulated to withstand mains voltage. In your country, that's 110 VAC; in my country it's 230 VAC. On top of that, the insulation must withstand transient voltage spikes ("surges") - AS1660.3 specifies a multi-core flexible cable must withstand a 3,000V AC hi-pot test for five minutes, so the insulation must be thick enough to withstand 3,000V RMS or 4,200 V peak.

The thin DC cable, on the other hand, only has to withstand 12 VDC. There is not any chance of voltage spikes on this line because the design of the power supply won't allow them. There is minimal electrocution risk from 12 VDC. Therefore this cable doesn't need much...

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Because we found a way to change the AC voltage levels from one to another before knowing how to do the same with the DC (i.e: the invention of the transformers ) and I can arguably say, if the nowadays technology of the power electronics and high power semiconductor devices had been reached in the late of 19th century, the DC would dominate over the AC.

Back to 1882, the first commercial distribution was DC, it was commissioned by Edison, a 24 km long cable at 110V to light Pearl Street Station. Transmitting power over a long distance at such a low voltage would inevitably lead to unacceptable losses. In 1885, the voltage transformers were invented, allowing stepping up the AC voltage before transmission (i.e, current is reduced and the losses can be highly reduced) and stepping it down to a voltage level appropriate to the distribution level. Thus, Edison lost the war of current against Westinghouse who was backed by Nicola Tesla.

Nowadays, the renewable energy...

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AC power transmission losses are greater than DC losses. That is hardly an industry secret. In fact the reason you can wirelessly charge a cell phone is because any changing current will radiate away some energy. You just need to coil the wire up to gather some of that energy in a convenient place. At the Three Gorges Dam in China, high voltage DC transmission lines were chosen to bring the power to the people for a variety of reasons. Many power companies are now starting to rethink the decisions that made AC transmission the obvious choice in the previous era.

Depending on the voltage, wire characteristics, and environment, other parasitic losses in AC transmission can become insidious, much more so than the relatively small radiative loss. At a mains power frequency of 50 or 60 hertz, the skin effect — where the majority of the current travels only on the surface of the conductor — starts to become more important. If most of the current is travelling in only a portion of...

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By Lee Wallender

Updated March 07, 2016.

When doing electrical projects on your home, you often encounter a type of metal-clad wiring called BX. This is not just a vestige of the past. Even with new projects, you still have the choice of using either BX wire or NM wiring (non-metallic sheathing).

Let us take a brief but comprehensive look at BX wire, its pros and cons, and how it performs against its newest competitor, NM wire.

BX Wiring: In Brief

Going under various names--BX, metallic sheathed cable, type AC, MC, or armored cable--BX is a collection of plastic-coated insulated wires (typically 14- or 12-gauge), bundled together and protected by a ribbon-like metal sheathing.

BX is contrasted with a newer wire, NM, which stands for "non-metallic." Instead of the metal sheathing, NM has a slick vinyl covering that is easy to rip and to pull through holes in studs. Romex is one popular brand of NM.

A chief distinction between BX...

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90% of my things run on DC current,
xbox, ps3, phones, TV(lcd etc), printers, everything I can see

Energy bulbs (these can run on dc or ac see youtube) /
LED household bulbs run on dc

i go into my kitchen and i think the toaster, kettle, microwave and fridge are all maybe 240vac

1) So why is the electric inside my home AC?
2) im not saying use 12VDC everywhere that would be ludicrous, but why is it not DC?
3) my xbox uses 12VDC and 5VDC same as my computer so obviously it can manage the change in voltage?
4) Could they not, with todays breakthroughs EITHER;
4a) Use High voltage DC to travel efficiently?
4b) or use the High voltage AC to travel, but when it reaches my home (or residential area) convert to 240VDC (or some ?VDC) instead of 240VAC

Then according to this really good youtube video ....


There would be less loss,
Less heat coming from...

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Even after two articles, and a tremendous number of page hits, there still seems to be lots of questions about HDMI cables. I credit this to the complexity of the topic and the mountain of misinformation out there, rather than any particular failing of the writing on my part. Judge as you see fit.

But the fact is, a recent reposting of my original article lit off a bevy of new questions. Instead of expanding on that already bloated article, I figured a new one would be a better idea.

On to 3D, 1.3/1.4, getting physical, and more...

There is no such thing as a 'HDMI 1.4 cable'
A "1.4" cable is a big misconception, and stems from truly terrible monikers from HDMI Licensing. There are two aspects to HDMI: the cable and the connection. The cable is dumb, just passing along whatever data you give it. The connection is where all the features are. There was a big push when 3D came out that you needed HDMI 1.4 to do 3D. This is true, but "1.4" is a connection...

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What are Straight and Crossover cable

Common Ethernet network cable are straight and crossover cable. This Ethernet network cable is made of 4 pair high performance cable that consists twisted pair conductors that used for data transmission. Both end of cable is called RJ45 connector.

The cable can be categorized as Cat 5, Cat 5e, Cat 6 UTP cable. Cat 5 UTP cable can support 10/100 Mbps Ethernet network, whereas Cat 5e and Cat 6 UTP cable can support Ethernet network running at 10/100/1000 Mbps. You might heard about Cat 3 UTP cable, it's not popular anymore since it can only support 10 Mbps Ethernet network.

Straight and crossover cable can be Cat3, Cat 5, Cat 5e or Cat 6 UTP cable, the only difference is each type will have different wire arrangement in the cable for serving different purposes.

Straight Cable

You usually use straight cable to connect different type of devices. This type of cable will be...

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