Understanding Wire Gauges | Ask This Old House

preview_player
Показать описание
In this video, This Old House master electrician Heath Eastman teaches host Kevin O’Connor about wire gauges and the applications for different size wires.

Master electrician Heath Eastman gives host Kevin O'Connor a lesson on wire sizes. Heath displays different wire sizes, ranging from thin to thick. He explains how each wire type gets its name and gives Kevin some examples of what each wire might be used for.

Wire sizing can be confusing. AWG? Aught? 14/2 vs 14/3? What does it all mean? Master electrician Heath Eastman teaches host Kevin O’Connor what these sizes mean and what wires of different sizes are used for.

Where to find it?
Heath explains the range in electrical wire gauges and how they vary depending on the load needed for a specific appliance. Electric current has a limited capacity dependent on the size of the wire. Circuits are available in different voltage loads to provide the exact amount of electricity required for a particular appliance. The larger the wire, the more current it can carry, meaning large wires support heavier electrical loads and smaller wires support lower loads.

Electrical wire can be found at your local home improvement store.

About Ask This Old House TV:
From the makers of This Old House, America’s first and most trusted home improvement show, Ask This Old House answers the steady stream of home improvement questions asked by viewers across the United States. Covering topics from landscaping to electrical to HVAC and plumbing to painting and more. Ask This Old House features the experts from This Old House, including general contractor Tom Silva, plumbing and heating expert Richard Trethewey, landscape contractor Jenn Nawada, master carpenter Norm Abram, and host Kevin O’Connor. ASK This Old House helps you protect and preserve your greatest investment—your home.

Follow This Old House:

Understanding Wire Gauges | Ask This Old House
Рекомендации по теме
Комментарии
Автор

While the ‘k’ does stand for “kilo” and the ‘c’ stands for “circular”, “kcmil” is not a metric unit of measurement, and the “mil” is not short for millimeter. One mil is 1/1000th of an inch, and a circular mil is the area contained in a circle with a diameter of one mil. A 500 kcmil conductor, therefore, is a conductor whose cross-section has an area of 500, 000 circular mils.

Willp
Автор

Back in the late 1970s we ran 4/0 in our church, the job supervised by two master electricians. I recall the wire was so huge and stiff I thought we would never get it through the big conduit but we finally did. It was a service to a large air handling unit as well as duct heaters and other electrics for a portion of the building. I'm grateful for the explanation.

ron.v
Автор

Great video but I have a concern about the explanation for the "wrong wire for the job".

If you use the wrong size wire, you're at risk for a fire (coming from inside the walls). It's not a matter of "the breaker is going to trip".

Let's say the breaker was rated for 20A, but you put in wire that's only meant for 10A of current. In a scenario where 15A of current is being drawn, the breaker will think everything is perfectly fine yet the wire will be melting down and eventually light on fire.

That's why it's important to put wire meant for 20A with a 20A breaker, etc etc

cweeks
Автор

25+ years as a UL508A industrial control panel builder. Mostly for the lumber industry boiler control, pump panels usually used the biggest wire. Great video on wire sizes.

iain
Автор

Appreciate videos like this. My high school students will be watching this in class next school year. I’d love to see more electrical videos! ⚡️

SikoraStuff
Автор

One thing you could have added was where "gauge" came from. it comes from the number of times the wire had to be drawn through a die or form to get it to the desired size. So, 14 gauge would would have been drawn through 14 sets of dies to get it to that size. Today it's a cross sectional area is more rigidly defined, but that's roughly equivalent to that. The X/0 sizes (pronounced "X ought") is just the number of 0s in that size, similar to "00 buckshot."

Also should have mentioned that wire size is not only determined by the amount of current going through the wire, but also the length and duty cycle of the device you're powering. Consult you local electrical code or electrician for more information.

And there was one mistake. MCM or kcmil is in imperial units. A mil in this context is 0.001 inches.

leviathanfafner
Автор

A good way to explain when to use 12ga (20 amp) to a home owner is on a circuit that will power an appliance that has a standard plug and cord, but produces heat. A toaster, coffee pot, hair dryer, space heaters, etc. It's more complicated, but this gets you most of the way there.

danrich
Автор

I would say more important than "right wire to the right appliance" is to say "right wire to the right breaker"... You get this combination wrong, that is when your house is at risk.

dddmmm
Автор

I'm still unclear about which two wires i should stick between my ears in order to receive the best This Old House reception. Oh wait, I now have the option to watch you on YouTube. Thanx guys.

pauls.
Автор

The only reason to use 14ga is to save money. All the normal general purpose outlets should be wired with 12ga on 20amp breakers IMO. If you separate lighting from outlets (a good idea, IMO) then maybe you want to use 14ga for your lighting circuits. But then if anyone decides to add an outlet and feeds it from a nearby switch, that outlet will be on a 15amp breaker. Wire is cheap compared to an electrician's time to come out and add circuits. Just use 12ga for your outlets in the first place. Or 10ga. That would be even better, but man I hate working with that stuff and multiple cables in a box.

Sylvan_dB
Автор

Kinda wish there'd been a closeup on that paper on the side near Kevin

Hezkezl
Автор

Great video as always! Learned something today 💥👌👍

javiergalvan
Автор

Heath got it wrong. kcmil is *not* "circular millimeters" and it's not metric. It is thousands (k for kilo) of circular "mils" where a mil is 1/1000th of an inch. (A 500 kcmil conductor is 253 square millimeters in cross-sectional area.)

johnhawkinson
Автор

Need one for plumbing pipes snd connectors next.

Abs, pvc, cpvc,
Schd 40, schd 80. Etc

CPTAINinsano
Автор

I thought that was brendan Fraser in the thumbnail

CPPRODUCTIONS
Автор

Metric is way easier🤯
Here in the Netherlands and some other European countries in a new house:
Mains connection is 3 fase, 230V, 25A with a separate neutral and ground.
The wires inside the breakerbox are 6 mm2 thick.
The circuit breaker are 16A with 2, 5mm2 wires running to your outlets/lights (except the switch wire for the lights, this one is 1, 5mm2). All the switches/outlets are designed for 16A 230V.

Do you need more power, use 2 fase, and the neutral. Stil not enough, 3 fase and neutral.

Still not enough, what are you doing with around 11000 watts on a single breaker? Yes you can get a 35A 230V mains connection and with that your allowed to install 20A 230V breakers, but this is expensive! The fee for only your connection with the grid is 3 times as high.

The only time you maybe can see a 4mm2 wire in your house is when you have solar or a car charger more then 10 meters (33ft) away from your breakerbox.

And yes there are 10 or 12 mm2 and thicker cables but not used for 99, 99% of the houses.

vlaardingerrr
Автор

This stuff is good for us ham radio operators to know, because we want to know how much current our transceivers need, and then match the thickness of the connecting wires from our power supply for such amounts of current.

denelson
Автор

Congratulations you have passed the test you got it right

rafealborbon
Автор

I’m a substation engineer and we use some wires that are so big they have a 4ft plus bend radius. Interesting stuff!

juliavanhoose
Автор

Thank goodness for the simplicity of the metric system. Cable size is the cross sectional area in mm2.

Generally in a domestic situation we use 1mm2, 1.5mm2, 2.5mm2, 4mm2, 6mm2, 10mm2, 16mm2.

We use 2 core and earth (for single phase loads), and 4 core and earth (for three phase loads).

loco