You could just lower the floor underneath the ladder …
But then you need to lower the floor beneath that one if someone was in that room …
Hmmm … maybe a ceiling lowering option is the safest all round
Still when skynet takes over the world it would just make it easy fot it to kill you (HA = Skynet) … or just hackers !
I have no doubt this is not required reading for you. Just a handy link for you to throw at the naysayers.
Nice page, good general review. Specifically the tables with actual numbers in them (anyone who has those tables memorized needs to get a life).
Personally my first degree is Physics, and second is Bio (third is DVM, but thats not hugely relevant here), so no big surprises on my part.
It’s not voltage that kills - its amperage. Under the right conditions, a person can be severely injured from a 12 volt car battery. The ability of electricity to damage biological tissue is dependent on both current and voltage. A very high voltage source providing a very low current does not carry enough energy to harm you. For example, a tabletop Van de Graaff generator (those charged metal balls you see at the science museum) can generate voltages up to 100,000 volts. And yet, children regularly enjoy shocks and hair-raising experiences from these generators without being harmed. In contrast, a high current (even at relativity low voltage) contains enough energy to hurt you. A better indicator of the danger of an electricity source is therefore how much current it gets running through your body, which depends partly on voltage but also depends on resistance and the amount of current the source can provide.
The safer way to change the lightbulb would be to suspend the automation and ensure the light is switched off. You may even need to pull the fuse or switch of the breaker.
Ceiling fan lights are below the fan. On top of all the other common sense solutions (and hilarious exaggerated ones) already posted, just don’t stand so f@ck!ng high on the ladder! I have never needed to stand with any part of my body in the way of the fan blades to change the bulb.
@Dale_Atkin Any chance you could share you code to automate your ceiling fan based on the difference between 2 temperature readings? I have been wanting to do something similar, but have no clue on where to start, especially the math part of the automation. Thanks
You obviously don’t have 20’ ceilings… yes, if I’m paying attention I can stand below the bulbs, but if I’m paying attention I’d switch off the automation before I go up anyways.
The most comfortable spot to stand happens to end up with my neck directly in the path of the fan blades…
I’ll try to remember to pull up the code for you (i’m not at home right now or I’d grab it), its roughly based on stuff I’ve seen elsewhere on here. Hardware wise I’m using two zigbee (aqara) sensors, hooked through a cc2530 (think that was the number) usb stick, and running zigbee2mqtt, along with a tp-link switch.
This has got to be one of the best threads I’ve seen on here in a while. Troll level, 10/10.
I can feel myself getting dumber with every post I read.
For some reason, I keep thinking of that ad that used to be on Aussie TV… “Charter boat, what charter boat?”
Binary sensor definition in configuration.yaml
alias: Bedroom Fan On
description: Turn on Bedroom fan when furnace running
trigger:
- platform: state
entity_id: binary_sensor.bedroom_temp_diff
from: 'off'
to: 'on'
condition: []
action:
- type: turn_on
device_id: 737ac52f3149926cbec1267aa61ec475
entity_id: switch.master_bedroom_fan
domain: switch
mode: single
alias: Bedroom Fan Off
description: ''
trigger:
- platform: state
entity_id: binary_sensor.bedroom_temp_diff
from: 'on'
to: 'off'
condition: []
action:
- type: turn_off
device_id: 737ac52f3149926cbec1267aa61ec475
entity_id: switch.master_bedroom_fan
domain: switch
mode: single
Very true, you can have a 10kV discharge at low current, and you’re totally fine, but if current is roughly equal, a higher voltage discharge is going to hurt more than a low voltage discharge.
The worst electric shock of my life came from a camera flash capacitor that was charged with 2 AA batteries (I was about 10 years old at the time…)
For anyone actually interested this is 3 days of data from the sensors. Day 1 is no automation, Day 2 I had the sensor too close to the fan and heating of the motor caused the ‘high’ temperature to be artificially elevated, Day 3 I moved the sensor and its working better.
Oh, where to begin…
I first have to say that I really like all of the imaginative ways people have come up with to make the OP safe. Kudos on those.
there seems to be a few misconceptions and a lot of overblown concerns.
First, there is the common misconception that 110v is safer than 220v. That’s pure crap from a practical standpoint. And it’s the exact reason that there are more electrocutions in the US than in other countries - people think 110v is “safe” because it runs thru the appliances they use every single day. “if it wasn’t safe they wouldn’t allow it in our houses!” so they take less precautions.
In a normal everyday homeowner situation 110v will kill you just as quickly as 220v will.
As someone above rightly pointed out it’s not really the voltage but the current that kills you. the voltage just pushes the current thru you harder at higher voltages. But, also, technically it’s neither. It’s the stopping of the heart due to the current flow thru it disrupting the electrical signals that normally cause your heart to beat. Or what many don’t know, is that even if the initial electrical shock doesn’t immediately cause your heart to stop you can still get into serious medical trouble much later because of the path that the current takes thru the body causes internal burns that cause a release of trauma induced chemicals that can overcome the bodies ability to clear them out and it messes up your internal body chemistry until you die. That’s the reason why you should still go to the hospital and get checked if you sustain a serious but not immediately fatal electric shock. They should monitor your vitals and blood chemistry for several hours afterwards.
It is commonly accepted that at a current of ~1ma (that’s milliamps or 1/1000th of an amp) you will get a “tingle”.
at ~10ma you will get an involuntary muscle contraction or a painful shock.
at ~100ma you can die.
As you can see from those numbers a normally breaker protected household circuit that is designed to protect your household wiring from catching fire that trips at 15amps won’t even think about tripping if you become a part of the circuit. It’s just another day at the office for that breaker while you are potentially being juiced at 150 times the lethal level. That’s why GFCI’s were invented.
As far as the “generally recognized as safe” level of voltage that’s based on the aforementioned resulting current flow thru the body and is based on the “normal” body resistance.
The typical assumed body/skin resistance is around 1000 ohms (it is usually quite a bit higher which is why the majority of people who get bit by 110v or even higher don’t all die - I’ve been shocked by 480v and I’m still here to tell the tale) but it could be a lot lower under some extreme conditions (sweaty, wet, sick, cut, drunk, etc). Maybe as low as 300 to 500 ohms. So based on typical worse case conditions it has been determined (in the US) that 50v is the maximum safe voltage to not need to take extreme safety precautions (LOTO, insulated barriers, 10 foot rule, and such).
Could you get shocked at less of a voltage? sure. If anyone has put their tongue on a 9v battery to test it you got shocked by 9v. Or you could take two metal spikes and jamb them into your palms and hook them up to your 12v battery and you might get a tingle or even a painful shock. But it’s not likely. And it’s even way less likely to kill you.
But…
I think there is a potentially overly paranoid side as well. I personally don’t know of anyone that turns off a breaker to change a light bulb. And the suggestion to actually follow industrially required LOTO is pretty extreme. It’s not like the person changing the bulb is disassembling the fixture to get into exposed wiring. If they are then they are doing it wrong. And at that point you can’t fix that kind of stupid.
Just turn off the switch if it’s controlled by one. if it’s not and if it’s controlled by a remote then just carry the remote up the ladder with you. Or remember to turn off the automation. Of course the bulb socket still could have voltage in it if the switch isn’t wired correctly. As the saying goes in the electrical field “just don’t touch the shiny metal parts”.
The vast majority of the time no one will get shocked and/or killed by replacing a light bulb, even if the socket is still turned on while they do it.
The vast majority of deaths by electric shock are from using non-GFCI protected circuits in wet locations. Or from getting into direct or indirect contact with overhead power lines (at 1000s of volts). Or working on the live internals of receptacles and such while having no idea what you are doing.
Of course, if you feel better by having the breaker turned off or instituting a LOTO program in your house then go for it. But as long as you aren’t totally stupid then changing out a light bulb is one of the least dangerous things you can do in your house.
Now as far as being afraid of getting knocked off the ladder…
have you actually seen how a ceiling fan starts? I think you’ll be fine even if it gets started up unexpectedly.
And to whoever mentioned the requirement for fall protection, the newest rule from OSHA is working at heights greater than 4 feet, not 6.
I don’t know about you but I don’t have anywhere in my house that meets the OSHA specified fall protection tie-off point safety level of being able to support 5000lbs if I fell from a ladder while working overhead inside my house. Of course, an SRL system can be used to reduce that requirement but not many people even have a normal safety harness let alone an SRL system.
But again, if you feel the need to institute a fall protection policy in your house then have at it.
Bottom line…
there is no way to “engineer out” all the dangers of any job in your house. Take the precautions that are at least in proportion to the real risk. If in doubt, safer is always better.
If you are that concerned about getting knocked off the ladder then turn the breaker off. If you don’t want to have to remember to turn off the breaker or even just turn off the automation then hire a “light bulb changer”. I’m sure there are any number of people who would gladly do that job as opposed to crawling around in the crawl-space or attic pulling in wiring.
And ultimately it’s your responsibility to take your safety into your own hands.
(Climbing off the soapbox now…the air is kind of thin up here… 
)
No, trust your HA or turn off the breaker.
Or shut down HA
How long are you up there to swap out a bulb…? Seriously, this whole debate is ridiculous. Just be sensible and you won’t get hurt.
This is why random everyday items have ‘do not eat’ written on them these days. 
I like the way you buy a bar of peanut brittle and it says on the side : -
Caution: Contains Nuts
Or even weirder : -
Caution; May Contain Nuts
Or when you buy milk, and on the package they write “contains milk”. You don’t say???
