if a 48V battery can be lethal, how about a 40V panel?

[MurphyGuy]

I would be interested in finding a report of anyone harmed by a 48 volt system due to electrical shock not involving a piece of metal.

I have serious doubts any exist.

48 volts is considered low voltage for a good reason.

 

[kromc5]

I remeber my college professor always saying its dangerous after 40vdc but I have watched many building 48v banks with no gloves. I bought geniue national safety apparel Class 0 glove for working on the breaker panels and batteries. Worst shock was from a 500vdc arc felt like my arm was hit by bat.

 

[Porch]

Well I am about to get banned for not following the "ANY dc voltage can kill under the wrong circumstances" line. So to everyone else, please do your research and look up the electrical code for your country and follow the safety standards for the voltage you are working at. Good luck to you all.

 

[Short_Shot]

Well I am about to get banned for not following the "ANY dc voltage can kill under the wrong circumstances" line. So to everyone else, please do your research and look up the electrical code for your country and follow the safety standards for the voltage you are working at. Good luck to you all.

You don't have to follow it, but you still shouldn't just tell everyone it's perfectly safe.

Not sure why you think you'll get banned for it though.

 

[Dzl]

Well I am about to get banned for not following the "ANY dc voltage can kill under the wrong circumstances" line.

One thing that is important to keep in mind on any forum, you have no knowledge of or control over your audience. This forum is primarily people with little to no electrical experience whatsoever beyond maybe some basic household stuff, and definitely majority of people here have no formal electrical training or electrical safety training, and at least some of us will come up a touch short in the common sense department. Any time discussing issues of safety, I think its important to bear this in mind. Reinforcing a culture of caution and respect is important, even if you take liberties/more informed risks in your own personal life.

You may have experience to know what is and isn't dumb or unsafe, you may make a comment assuming that best practices that seem like no-brainers to you (no rings, no uninsulated metal tools, no licking battery terminals ) will of course be followed, but what are unspoken no-brainers to you, or known and understood risks, many readers will be 100% oblivious to, electricity is a foreign and unintuitive thing to many people, unlike swinging a hammer or axe where the risks are intuitive and obvious, for the uninitiated (and I include myself in this category) best practices and absolute don't-dos are not all obvious.

Now these things are not suddenly true at 48V nominal (which should be noted is almost always above the 50V threshold at almost any relevant state of charge for a 48V lifepo4 bank) and not relevant at lower voltages, but the higher the voltage, the higher the potential current, the more caution and respect should be applied in my non-expert opinion. That doesn't mean it shouldn't be able to be discussed/debated rationally among informed, experienced people, but I think its quite important that when doing so you make clear, that that is what it is, not make cavalier blanket statements, and that anyone who is unsure should err on the side of caution.

The TL;DR understand the power of and reach of your statements on a public forum and the lack of control you have over your audience, and the relative inexperience of the majority of people on this forum.

So to everyone else, please do your research and look up the electrical code for your country and follow the safety standards for the voltage you are working at.

Good advice. And if you don't know, err on the side of caution.


Note: the above is a general comment, not entirely directed at you or anyone in particular. More my thoughts inspired by some of the comments/disagreement in this thread.

 

[Porch]

I never said 48v is perfectly safe. I am stating the electrocution risk (and only that risk) is low to none existent. It's classified as low by many government electrical standards world wide. You can in fact, take your sweaty hands and touch both sides of a 48V led acid battery and not end up getting blown through a wall or end up a smoking pile of goo on the floor, regardless of what movies tell you. A 48V battery is not lethal in terms of electrocution.

There is other risk involved (dropping metal or creating a short), and those risk are not dependent on the electrically being 48v, but also apply to 36v, 12v or 6v. You need to take care when headlining a 12v battery or a 48v battery. (See the excellent post above on how you have to be more careful at the higher voltages.)

As for the inexperience audience on this form. This form is filled with inexperienced people asking and people telling them how to handle high voltage/high current all the time. Look down the what's new and see how many people are asking how to wire in a none UL approved inverter to their home breaker panel, by themselves. The only answer that should be "hire a certified electrician, pull the proper permits, get the job done correctly and safely. " But that answer is almost never given and it seems perfectly fine to tell someone how to tap into 240v breaker panel.

But then we get the advice that "ANY dc voltage can kill under the wrong circumstances". Implying the same level of care should be taken be it a 48v battery, or a 1.5v AA cell because it's better to be safe. How many of you use rubber gloves to install new batteries in your TV remote, just to be safe?

I am trying to explain the risk involved so the end user, even inexperienced, can make an informed choice on what risk they are willing to accept.

 

[sunshine]

As for the inexperience audience on this form. This form is filled with inexperienced people asking and people telling them how to handle high voltage/high current all the time. Look down the what's new and see how many people are asking how to wire in a none UL approved inverter to their home breaker panel, by themselves.

I understand. However if anyone blows themselves up taking advice from an internet forum they only have themselves to blame.
I hope we never get to see a society so set on liability that it has become so profoundly boring,,,and it's heading that way.
Already electronics has limited modifications to newer vehicles. 800v EVs are going to shut out the automobile diy completely once the regulators see a new area they can start regulating in!

 

[toms]

But then we get the advice that "ANY dc voltage can kill under the wrong circumstances". Implying the same level of care should be taken be it a 48v battery, or a 1.5v AA cell because it's better to be safe. How many of you use rubber gloves to install new batteries in your TV remote, just to be safe?

I am trying to explain the risk involved so the end user, even inexperienced, can make an informed choice on what risk they are willing to accept.

Agreed, it’s way better when giving advice (especially safety advice) to give examples to illustrate the risk.

 

[12VoltInstalls]

OSHA:
“We are aware of documented cases where serious injuries occurred when employees contacted live parts operating between 50 and 100 volts, DC. See, for example, https://www.osha.gov/pls/imis/accidentsearch.accident_detail?id=775742&id=14295083.3 In fact, although OSHA's standards require guarding starting at 50 volts (AC or DC), it is not necessarily the case that voltages below that level are completely safe, We have heard of cases in which auto mechanics have sustained serious injuries working with 12-volt or 24-volt (DC) vehicle batteries.”
“OSHA considers all voltages of 50 volts or above to be hazardous. Electric current, not voltage, passing through the human body causes injury, and the amount of current passing through an object depends on the resistance of the object. As explained in Appendix C to 29 CFR 1910.269, the internal resistance of the human body is 500 ohms, which is the minimum resistance of a worker with broken skin at the point of contact. The current through 500 ohms from a live part energized at 60 volts would be 120 milliamperes. This level of current, either ac or dc, is sufficient to cause serious injury”

 

[Will Prowse]

Next to melting stuff (and that can be done at 6V), please explain how 48V is deadly.

48V batteries, such as lifepo4, charge to 57+ volts. That is over 50 volts, and under the right conditions, can kill.

 

[Short_Shot]

I never said 48v is perfectly safe. I am stating the electrocution risk (and only that risk) is low to none existent. It's classified as low by many government electrical standards world wide. You can in fact, take your sweaty hands and touch both sides of a 48V led acid battery and not end up getting blown through a wall or end up a smoking pile of goo on the floor, regardless of what movies tell you. A 48V battery is not lethal in terms of electrocution.

There is other risk involved (dropping metal or creating a short), and those risk are not dependent on the electrically being 48v, but also apply to 36v, 12v or 6v. You need to take care when headlining a 12v battery or a 48v battery. (See the excellent post above on how you have to be more careful at the higher voltages.)

As for the inexperience audience on this form. This form is filled with inexperienced people asking and people telling them how to handle high voltage/high current all the time. Look down the what's new and see how many people are asking how to wire in a none UL approved inverter to their home breaker panel, by themselves. The only answer that should be "hire a certified electrician, pull the proper permits, get the job done correctly and safely. " But that answer is almost never given and it seems perfectly fine to tell someone how to tap into 240v breaker panel.

But then we get the advice that "ANY dc voltage can kill under the wrong circumstances". Implying the same level of care should be taken be it a 48v battery, or a 1.5v AA cell because it's better to be safe. How many of you use rubber gloves to install new batteries in your TV remote, just to be safe?

I am trying to explain the risk involved so the end user, even inexperienced, can make an informed choice on what risk they are willing to accept.

No.

To most of this post.

Especially the sweaty hands on a 48v battery part.

 

[NPhil]

About 50 years ago, the electronics shop (we had shop classes in public schools, once) teacher told us to keep one hand in your back pocket while reaching into stuff which might have high voltage on it. My personal experience with low voltage is that I never noticed 12V through the skin, while handling it for years, but when I got a 24V system, I started to notice it biting me if I had a hand across positive and negative. That's for contact through the skin. a wrench, or anything metallic, and you notice! Never do that, and wear, at an absolute minimum, "glasses" (polycarbonate lenses, I mean), to keep flash and splatter out of your eyes if you should happen to do it accidentally! 48V, I don't remember getting across, but, I guess it would bite twice as hard as 24V.

 

[time2roll]

I think most of these panels have MC4 or similar connectors. Get your wiring set first, then plug and play.

 

[toms]

OK, i’ll be mindful of not sweating profusely or bleeding when i’m working around my 48V (55V) battery, and i’m definitely going to run a careful eye over my welder next time i use it!

 

[A.Justice]

Electroboom above shows him touching 170V and 300V DC. He is not dead as he is still making videos.

People are also tazed with 10-100k volts shoved into two metal rods imbedded in their chest. Most of the time they come out fine. Dog shock collars can easily be over 1000v as well. I've hit 240v AC with sweaty salt-water covered hands more times than I can count and, other than being a little confused, I still finished the job up every time.

That being said, I know someone who was hospitalized from brushing a 120v house wire.

It's not the voltage, or current alone that kills, it's WHERE on your body that current is passed through. That's why I work on high(er) voltage with a ground strap and keep one hand behind my back. Don't EVER give current the chance to pass through your heart.

 

[Sky Noris]

Any power can be dangerous if not dealt with responsibly. I do know that NFPA 70E starts at 50 volts AC or DC. Best advise I could probably give is never do anything that you aren't 100% sure that you will be safe.

 

[12VoltInstalls]

Best advise I could probably give is never do anything that you aren't 100% sure that you will be safe.

Maybe better stated, “never do anything that you aren't 100% sure that you can explain why you will be safe.”

 

[Lt.Dan]

Once when I was younger, I was working on an old 74' Dodge Powerwagon, adjusting the timing. The distributor is in the back of the engine on the old 360 LA engine, and I remember sitting inside the engine bay, with my butt on the passenger fender, my feet on the frame rail (there was a lot of room in the engine bay back then!), my right hand supporting my weight on the front end (grasping the top of the grill to be exact), and my left hand on the top of the distributor, rotating it while my friend read the timing light. I didnt know this at the time, I assumed it was all 12v, low voltage in the entire truck, but there could be 20,000-50,000 volts running through a distributor. I felt a shock jump through a plug wire (very thick rubber insulated plug), run through my left hand, up my arm, across my chest, down my right arm, and through my right hand into the bare aluminum grill. The shock caused me to grip the grill so hard that I put a dent in it, my head jerked back and I railed my head against the open hood.

Not fun. I adjust timing with the engine off now. The ol' guess and check method.

 

[stienman]

What you don't learn from good advice will be more painfully taught through repeated experience until learned.

 

[SoFar]

I didn't realize "the different reactions" I would get when I started this post. Wow

I was speaking to a friend of mine who is an electrical guy and does a lot of work on high end boats and asked him the same question, I posted. He told me about 30 years ago there was a big boat in town that had 10 12V batteries in Parallel. There was a guy doing some work/maintenance on them and he dropped a wrench on one of the batteries. My understanding was there was a huge explosion and nothing left of the stern of the boat.