AC vs DC Switching Demonstration with Arcs

The difference between switching AC and DC.
With DC, the arc formed as the switch contacts open is far more difficult to extinguish, and can cause significant damage.

[stuarthossack]

For me at least, this is the best demonstration and explanation of AC and DC switching I have seen - superb, thank you.

[johnkeepin]

A good demonstration. Not just switchgear, though; I've got a solar PV setup in my house, and on the inverter there is a warning label: "DO NOT disconnect DC plugs and sockets under load - turn off AC supply first." There is a pair of switches for disconnecting both ends, but it's wise to switch out the AC end first (then the inverter shuts down internally). Of course, those who are used to DC electrified railways will be familiar with what happens from time to time!

[gadgetgeorge]

Thanks for this. As a kid I used to play around with old switch gear that had “AC only” stamped on it. This really baffled me until now 👍

[roselima]

I learned a lot, i never realized it is that much of a difference, thank you

[mrrkrr]

I've only ever seen one other video like this before and this one does a better job of displaying the difference. Great video and thank you for showing everyone this important switching concept!

[antonm.]

Thank you sir! As an electrician in Europe I found this very informative and helpful as well very well presented. It is very easy to understand. I have some advice or a challenge for you. Please do the same or similar video with name and tags about photovoltaic, solar cells so it will reach more people and bring you many new views also. There were 6 roof fires in my near area just this year, just because of photovoltaic. As I heard news from investigators recently, there was probably combustion because of an arc.

[NobodyNew]

The one issue i found with this demonstration is DC voltage, multimeters usually show RMS of AC voltage and not peak voltage, so if you use 240V AC, the DC voltage should be around 340V and not 240V.

[JonRushton]

I've always known the difference between AC & DC, but never made the connection (no pun intended) as to why a spark with AC is much smaller. Brilliant explanation, thank you for appearing randomly in my recommended feed!

[aurora]

Would be interesting to repeat the experiment using 12v DC at different current ratings. I am using standard mains 10a light switches for a 12v DC solar installation running some 12v 10w LED floodlights.

[brzydka_i_bestia]

Explains why relays have different voltage rating for AC and DC.

[edinfific]

I have learned this the hard way when I used solar panels to power my water heater directly. Had to replace the thermostat because of burnt contacts.

[keithrobinson]

Brilliant demo as usual thank you. I wish other electronic experts were more approachable I’ve been trying to ask electronics user groups etc for a solution to my problem but it seems too simple for them to even reply? Thanks for sharing your considerable knowledge, I’m sure many appreciate it as I do.

[markhorton]

Nice demo of how conductive air becomes once it turns to a plasma.
Fixing small powerful magnets in the correct orientation close to the contacts can "throw" the arc out in a curve and help to snub it for DC. It works for AC too but the arc goes in two directions so positioning can be tricky.
Heavy duty DC contactors sometimes have them built in.



Viewers, don't make the mistake of choosing "gold contacts" thinking they are better. Silver is best for DC even at the small scale. Choose gas envelope enclosed contact relays if possible, the ones opened by a rotating armature are faster, if you can get them big enough.


I have long been puzzled by the regs quoting higher safe voltages for DC. Crunching your muscles in one direction rather than making them "ripple" they are a lot more painful, or so I assumed, and seeing it happen to others that conclusion seems safe.

[jusb]

probably explains why a dc inverter arc welder is much easier to strike than the older ac welders

[electricalnews]

Καλημέρα φίλε μου. Είσαι συνάδελφος καταπληκτικός και κάνεις πολύ καλή δουλειά. Μπράβο!! Σε παρακολουθώ... I'm Kostas From Greece!!

[ats]

It would be interesting to show how the arcing can be reduced using different types of snubber circuits...

[ranmc]

Spectacular video. Nothing better than a visual to learn

[andreim]

BigClive needs to pick up on this and step up the game until it all goes horrible wrong 😈😈😈

[robertgaines-tulsa]

It would be great if you covered the construction of DC switches and showed them in operation. I noticed that some people insist that DC is an overall better system because of the efficiency you get with UHV transmission. I won't get into a debate on whether AC or DC is superior, but I will say that it looks like AC is more practical in the home so you can use higher voltages to use cheaper, thinner wires to distribute power while using more cheaply made switches. It doesn't look like you could use a 120-240 volt thermostat very reliably on DC without the added complexity of arc suppression. Certainly it would seem that you would want AC during a malfunction so the arc could much more dependably snuff itself out to help prevent a house fire. On a side note, I notice that your voice seems to drop in intensity in the middle of your sentences, and it becomes harder to hear you. Usually, I have the auto volume on with my television to help deal with the large variances in volume level on YouTube between channels. I prefer to turn in off when I play music. Anyway, most people likely don't have a volume compressor on their audio. Perhaps you need a lapel microphone? You can get them rather cheaply on eBay if your camera can use an external microphone. Many people are just using their smartphones these days also so I don't know what you are using. Anyway, it should help boost your subscriber count to help normalize your audio pickup.

[joshuabest]

Can you dismantle a a.c. breaker and dc breaker next to each other to show the diffrence