High voltage warning

Continuing the discussion from Howto install OpenWrt on Asus RP-N53:

First of all, Linux expects the user to know what he is doing. The same is true for electricity.
As we see almost every day in the forum, users oftentimes do not know what they are doing.
A warning seems advisable.

Proposals for an infobox which can be included on all 80 devices which are listed as mains powered:

Which one do you like better?
Is the text clear enough for everybody to understand the risks involved?

Comments are welcome!


thanks @tmomas for your swift and collaborative action on this concern...


  • i'd be happy with the red one... with a picture of a skeleton getting lit-up
  • and perhaps a small line about it also possibly being illegal(check the laws and regulations in your region)

suppose would be consistent/prudent to also attempt to implement a similar warning within the forum... either one by one per posts as noticed ( header? ) or perhaps a pinned topic in hardware?

I agree that the first one looks more intimidating.

Some playing around:

  • ISO 7010 W012 Warning sign added
  • different background colors


One more:

  • text re-arranged
  • corner rounding removed
  • width reduced



While I don't have a real preference for either of them, I think this is a good idea. A similar warning is probably in order for all devices with integrated xDSL modem as well, as the phone lines might carry up to 90 volts (one would hope that $user disconnects their device from the phone line before messing with it, but…).

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The new high voltage infobox in action: https://openwrt.org/toh/cloud_engines/pogoplugpro#installation_process

Comments are welcome!

Also, feel free to add this infobox to affected devicepages!

See https://openwrt.org/meta/infobox/start#high_voltage_warning_mains how to do this.



Feel free to add this infobox to affected devicepages!

See https://openwrt.org/meta/infobox/start#high_voltage_warning_dsl how to do this.


So nice, actually my new EdgeRouter 4 is connected directly to the 230V AC power line.

I guess that is why most home router manufacturers only use a AC/DC adapter with low voltage to get them CE approved so the customers survive when they lick on the connector or do something else they shouldn’t do.
I got the feeling mostly the industrial and business class network devices are the high voltage devices🤔

Just a note that
"High Voltage" refers to voltage above 1000V
"Low Voltage"refers to 50 to 1000V
"Extra Low Voltage" below 50V

I prefer

"Danger : Risk of Electric Shock"

Good point!

Since we can not scare anybody with "Low Voltage", how about this one:

I tried to avoid "high voltage" in the last sentence and replaced it by "live parts", but
I'm not really happy with that yet.

Make sure to keep your fingers, conductive tools and serial cables away from parts under mains voltage at all times!

Alternative phrasing:

  • parts under powerline voltage
  • parts under dangerous voltage

Any other proposals?

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High voltage electricity refers to electrical potential large enough to cause injury or damage.

There are no real voltage level for high voltage per definition. If it can hurt or kill humans or animals then it is high voltage. That is all voltages that draw more than 30mA through the standardised human body or a animal.

High voltage per the definition of >1000V is the voltage level when the current starts to move as a corona effect, air is ionized and discharge length is 1000V/cm.

In Sweden we did name this from the year 1909 as Starkström (kind of ”strong current” in english) that had the definition of ”all currents that is dangerous for humans and animals”. And in the regulations (was called the “The blue book” because of it’s color) from the electrical agency had three chapters A (common rules), B with safety rules for voltage level under 1000V and chapter C with the safety rules when at voltages over 1000V.
But the definition of ”strong current” was in chapter A so it applied for both chapter B and C. Then someone invented the EU...

The problem is that I am not aware of any english speaking country that made the definition of “strong current” as the definition of dangerous and not dangerous. Instead high voltage became the definition in English.

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High voltage under 1000V

I understand.

However in some countries if you label something as "danger high voltage" then there are rules where that equipment can be installed and signage that also needs to be erected in that area.

So by incorrectly labelling something as high voltage you create issues for the installation of the device.


Well this is the problem. EU has one rule, USA has another rule. Asia I guess have some rules.

The physics are the same in the whole universe but how the politicians has decided how the warning is supposed to look like is a circus.

We can’t even agree on a world wide connector standard...

One alternative is to leave the responsibility to the manufacturer of the hardware that at least for the CE mark is responsible of the electric warning.

How many devices have the actual problem that requires the user to actually open up the device to use OpenWRT?

EdgeRouter 4 and my EdgeSwitch has the console connector on the front or back panel.

Original (high voltage)

Modified (risk of electrical shock)

Shall we switch from original to modified?
If yes, which of 1, 2, 3 would you prefer (taking into account that we have users that do not natively speak english and possibly use a translator).


It should be something like

"Only qualified person should open device."

My reason is that the person should decide if they have the skills to work with mains voltage and only then proceed. There is more too it than not touching things. For example I have seen unqualified people leave equipment that they are working on in exposed state while they go for a lunch break or at home with young children.


Then you are saying: Any mains powered device which requires serial access (and hence opening the case) can not be flashed with OpenWrt because no user out there is qualified to handle mains voltage (exceptions confirm the rule).

Since users usually do not care about being qualified or not, we should at least give some practical advice that helps to avoid the worst.

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