An idiotic question about AC and shocks.

[TechGeek]

Re: An idiotic question about AC and shocks.

wat

[goontron]

Re: An idiotic question about AC and shocks.

i have been shocked a few times wearing rubber soled boots in a dry wooden shed . this was by touching one side of mains only . sometimes it activates the breaker .

Huh, and here i thought capacitive coupling was only that extreme at VLF and up...

[eccerr0r]

Re: An idiotic question about AC and shocks.

Out in the "industry" do beancounters and managers regularly expect an electrician to work/actually touching live devices, depending on your insulation that you remain alive (versus the insulating PPE is secondary and using your head not to touch live wires primary?)

Or are things normally powered down before working on them/use only insulated tools?

Just wondering about the profession... makes even working on live power supplies like child's play... unless you consider sticking keys into receptacles child's play.

[goontron]

Re: An idiotic question about AC and shocks.

^ Having does 277v lighting live and seen a panel get installed and connected to the busbars live in an apartment building before, not to mention linemen working on live lines, id say its fairly normal.

[stj]

Re: An idiotic question about AC and shocks.

normal, you need the lights and if your fault finding you need the working conditions.

you use gloves, and insulated or ceramic tools.

[eccerr0r]

Re: An idiotic question about AC and shocks.

Well there are flashlights and testing of course needs to be done live, but what about actually connecting things? Sparks can also cause problems when doing human-initiated connections (versus spring loaded connections that minimize high-resistance time.)

There's also the warning to make sure that line connected inverters don't back power during a blackout...

[RJARRRPCGP]

Re: An idiotic question about AC and shocks.

Of course you need a return path.
In Europe we have hot and neutral, the neutral you can touch while being grounded 99% of the time, it will be at ground potential (the other 1% of the time it's not and you die during this test).

The hot you can touch as long as you are not touching neutral or ground, and ground can of course be whatever path the current can go, for example through a radiator, or through simply damp floor.

Think of it just like a bird sitting on the powerline, it's just fine as long as it does not touch anything grounded...
Or think of it another way: take a hot wire and touch it to the floor, carpet etc, do you expect any sparks?
Next put it against something damp, or against the kitchen sink and see what happens.

P.S: This is why it's a really good idea to have a GCFI breaker, in every case expect where the neutral is the return path the breaker will trip, like a child poking a screwdriver into a power outlet.

How is it where you are? What is the max voltage and it does sound like you have 2 legs (hots) for a total of at least a rating of 460 V. If you have 2 legs for 230 V, then you don't need a neutral for 230 V devices. But you do, for 230 V devices, if you have 460 V service or higher!

In U.S.A. and probably Canada, each leg is only 120-127 V and 2 legs 240-254 V. For 120 V-rated devices a neutral is required! Without a neutral, you can expect a surge (overvoltage) to 120 V-127V devices! (and the leg that's under heavy load, will sag!) (a.k.a brownout)

I know, this may sound strange, for the non-requirement of a neutral, when voltage is multiplied by more than 1 hot! Because having just a line-and-ground, sounds just like DC, LOL.

[Spork Schivago]

Re: An idiotic question about AC and shocks.

[I]...
GFCI's are better than tamper proof plugs, if a cord is pluged in but the wire in the cord itself is damaged/exposed, the tamper proof receptical won't protect against that but the gfci will.

We've been purchasing the tamper proof GFCI receptacles, which are tamper proof and have the GFCI built in. Are you saying regular GFCI are better than these? Or regular GFCI are better than just tamper proof receptacles that don't have the GFCI built in?

With our tamper resistant ones, it says you need to put equal pressure on both sides in order for the plastic to move out of the way and the contacts to be exposed. Only problem is they're a bit larger than the normal gang boxes and we need to break off the "ears" (which we're not using anyway)

[Spork Schivago]

Re: An idiotic question about AC and shocks.

I think they want TR outlets because they're... cheaper.

They say TR outlets cost $0.50 more to make, GFCIs are like 6x the cost at least.

Granted last I went by the Despot, the TR outlets were fairly pricey... but forgot how much they were charging...

Then again the GFCIs were significantly more expensive.

No, we want tamper resistant because of our daughter. And these are expensive. I hate to paste links because they tend to go dead, but these are the ones we've been purchasing:

https://www.homedepot.com/p/Leviton-...-03W/303954635

It's a Leviton 20-Amp 125 volt tamper resistant GFCI receptacle, three pack, that costs use 42.83$ for the three pack.

[R_J]

Re: An idiotic question about AC and shocks.

GFCI tamper proof would be the way to go, What I was saying is that if the receptacle was ONLY tamper proof, and what ever was pluged in to it had a fault, you could still get shocked. But if it was gfci it would trip out.
For example the a/c cord from the portable stereo gets unpluged from the unit, and someone stuck the cord in there mouth.

[Spork Schivago]

Re: An idiotic question about AC and shocks.

What you are talking about is split phase and it's 180° apart.
120° separation is used by three phase systems.
In the US that would give you √3x120v = 208v


The current flows.
It's better to think of it as a wave, it provides continuous motion.


You always need a return, it's always a neutral, ground is just for safety.
However in a two phase system the "neutral" will be the other wire in any given situation.

Okay, let's revisit this again so I have a better understanding. First off, I did mean 180 degrees, not 120. I understand the degrees I believe. But in a hypothetical system where there's 240VAC and just two hots going to the receptacle. No ground, no neutral.

I look at AC as a wave. I realize the voltage is not always 120VAC. That's the peak. With the above setup, when you have just two hots, you're saying one of them will act like a neutral...would it be both would be hot but also act like a neutral? With the one hot sending the wave down to the receptacle and then the other hot, back to ground (earth), and the other wire doing the same? This is where I get confused, when you remove the neutral and ground, and just have two hots. I would have thought you wouldn't get a receptacle to work in a situation like that. But it seems it would work and the neutral and ground are just for safety. Please correct me where I'm wrong here. I have not tested the above situation, it's just based on how I interrupted something someone said to me, who seemed to know a lot about AC and had a truly fundamental understanding.

Then he did not know what he was speaking about, or you misunderstood.
A GFCI has nothing in common with a lighting or surge protector.

He is highly spoke of, but is also training his son, it could have been the son who I talked to, who DOES NOT fully understand everything currently. That caused some issues for us when we got our new wiring inspected. We failed because of how the son wired one of the 240VAC receptacles. He never marked the white HOT wire with black. We had to fix that mistake. Worse part, same inspector that passed the professional electrician! I think he was just so used to working with him, he figured his work was good and never checked the actual panel. Now though, the inspector told us we didn't have to go through the hassle of getting a permit and getting it inspected, so long as whatever we were going to run, we sent pics to him first to make sure it was up to code, any questions, just text him, and send pics of it finished. If anything happens, he'll vouche that it was inspected during this visit. He said that should save us a lot of money. We're trying to fix all the previous owners electrical mistakes, and there are a lot. But doing it one room at a time costs a lot. This makes it a lot easier to work.

It has nothing with physical protection to do.
Following on from my answer above a GFCI is a device that monitors the current going out on a phase, making sure it comes back over the neutral.
If it does not it means it is leaking out somewhere else, for example into a child poking his fingers into an electrical outlet.
The GFCI then trips.
A GFCI is simply a coil with the hot and neutral wires passing through it.
For example the hot wire carries 10AH, it then follows that the neutral must carry 10AH back.
This nullifies any magnetiuc field in the coil, so it reads "0"
If any current goes back any other way than via the neutral then the coil will get energized tripping the breaker.

Thank you for explaining that to me.

This works just as well in a two phase system without a neutral, because all the current must still come back to the source (transformer or generator) alternating via the other wire in any given point in time.
Normally in Europe a whole house GFCI breaker is installed in the panel, cutting the incoming mains in case of detected fault.

If I were to replace the 200-amp MAINS breaker with a 200-amp MAINS GFCI breaker, that should essentially make all of the breakers that aren't GFCI equivalent to GFCI, and make all the non-GFCI receptacles equivalent to GFCI receptacles, correct?

[Spork Schivago]

Re: An idiotic question about AC and shocks.

eccerr0r's comment made me want to do the math here. Going to use my house as an example here. It has 3 non-wet location branches, with 5 sockets each (its a 60 amp panel, what do you expect?).
Locally, prices are as follows:
GFCI $12.88
Standard Comercial socket $1.99
Tamper resistant $4.97

For GFCI protected branches with standard sockets it would cost $62.52
For all tamper resistant it would cost $74.55

But, GFCI comes with the cost of nuisance tripping. Radio (CB, Ham, etc) operation for one. Another being old equipment like my Yamaha CR-640 that has a resistor from line to the chassis, and thus to ground via my ham shack ground radial, which has enough leakage to trip more sensitive GFCIs.

Personaly, i'm going to stay with my commercial grade, non-tamper resistant sockets clocking in at $29.85, but thats not the point here.

For the business stuff, we use industrial grade, which adds up and doesn't have those safety features, but are "locking", so provide some part of protection, and are high up, where a child cannot reach. When she can, hopefully she'll know enough not to stick things in. All our business stuff runs off somewheres between 100VAC ~ 240VAC. Most auto-sense, no switch.

Do you guys not have the GFCI / tamper proof combos where you live? That's what I meant when I said tamper proof.

Also, remember what (I think) R_J said. Normally, people will use one GFCI at the beginning of the circuit, and then daisy chain non-GFCI receptacles to it. It has to be done in a certain way, but the receptacle should have instructions on how to do this, and in doing so, you essentially "convert" the non-GFCI receptacles to receptacles protected by the GFCI receptacle. It's equivalent, I believe, to using just all GFCI receptacles.

In the basement, where I'm replacing the receptacles, I'm putting them on a dedicated circuit because of what they're used for (there's only three, so that's not a big deal).

I need to find a way to trace wire that goes through diagonally in the basement through a support stud and someplace upstairs. They're not hooked up to the panel. Got two there. I think I know where one runs, but the other, not so much....only thing I can think of us taking a section of the wall out and looking, for finding some device that sends a signal down one of the lines that I can read with some other device, without removing the walls. That'd be nice.

[R_J]

Re: An idiotic question about AC and shocks.

the gfci will have LOAD terminals on it for connecting the other down line non gfci recepticals, there not just connected to the gfci terminals

[Spork Schivago]

Re: An idiotic question about AC and shocks.

https://www.evaluationengineering.co...safety-testing

Little bit of a long read, but WELL worth it! Highly suggest anyone thinking of passing it up to actually read the whole thing. THANK YOU!!!!!!!!!!!

Saved the PDF and gonna print that beast.

[Spork Schivago]

Re: An idiotic question about AC and shocks.

That YT video is good, this one is also worth watching: https://www.youtube.com/watch?v=wR6g38Pxwog

On the point of cost for GFCI outlets, I understand from your comments in the US you commonly use a GFCI device for each outlet?
Here in Europe it's pretty much always a panel breaker.
For example one of the cheapest is this one on Elfa: 300-76-724
So around €35 but that's going to protect every outlet, it's a 3-phase GFCI...

In the US, at least where I'm at, we're REQUIRED by code to have an GFCI receptacle anywhere from 6 feet or closer to a source of water. We can daisy chain that receptacle to other ones, or instead, we can use the GFCI breakers.

Most people, for old construction, from what I've seen, will use one GFCI breaker and then daisy chain the other receptacles to them. For me though, all three receptacles are the only thing on those circuits, so daisy chaining isn't an option, unless I run wire to connect them together (don't want to do that). Not sure why the previous owner had it that way, but they did, and I'm just fixing some small issues.

For the basement, I like the receptacles, so I can kill the power without having to run to the panel if I need to. But I really like the idea of using those GFCI breakers. I want to replace all my square-d (homeline I believe) breakers with the GFCI ones.

New construction, here, in my county, actually requires arc-fault breakers, however, a while ago, they required GFCI breakers. I believe that's only my county.

If I show you guys a picture of my panel opened up, could you show me which type of GFCI breakers are the correct ones to purchase, at Home Depot's website or something? Or would I need a new panel all together made specifically for this type of thing? I'm okay and feel comfortable installing buss bars, if I need to.

[Spork Schivago]

Re: An idiotic question about AC and shocks.

You get shocked only if there's a path to ground and it's going through you.

Tile on concrete is conductive, and is grounded if the concrete touches the ground. If you contact a voltage source (like an outlet or a buss bar in a breaker panel) and you're standing barefooted on something that's conductive and is grounded, you're going to get a shock.

Rubber is insulative. That's why rubber-soled boots are usually mandatory when working on 3ph 480V industrial equipment. You can grab onto a LIVE 480V wire, wearing rubber-soled boots on dry ground, not touching anything conductive (except the wire), and you will be at the same voltage potential the wire is at. Just warn other people not to touch you or hand you anything.

That's what I thought, thanks. Just to point out though, rubber is, like you said, insulative. I don't think we have a pure insulator, do we? High enough voltage, it'll arc through anything.

Old high school teacher went to a display where this guy wearing giant rubber gloves would touch these wooden poles to live high voltage wires and they'd just explode. Most people consider wood an insulator. My teacher suspected it was because of the water in the wood, which made sense.

So I'd think if the voltage was high enough and the rubber wasn't thick enough, you might be making a deadly mistake touching a high voltage source. Would this be true?

[stj]

Re: An idiotic question about AC and shocks.

i have seen car HT cables with pinholes burned in them where they touched the engine.

[petehall347]

Re: An idiotic question about AC and shocks.

i have seen car HT cables with pinholes burned in them where they touched the engine.

it does happen . blown enough good quality digital multi-meters just by getting to close to eht stuff .
its probably only around 18000 volts or more . smallish current if working properly .

[budm]

Re: An idiotic question about AC and shocks.

https://safety.grainger.com/people/5...ctrical-gloves

[Spork Schivago]

Re: An idiotic question about AC and shocks.

GFCI tamper proof would be the way to go, What I was saying is that if the receptacle was ONLY tamper proof, and what ever was pluged in to it had a fault, you could still get shocked. But if it was gfci it would trip out.
For example the a/c cord from the portable stereo gets unpluged from the unit, and someone stuck the cord in there mouth.

So a more advanced question then. GFCI is better than Tamper Proof you're saying, but GFCI tamper proof is better than just GFCI. Now say we install either GFCI breakers or arc-fault breakers or GFCI / arc-fault breakers.

Would tamper proof still be needed? I originally loved the idea of the combo GFCI / arc-fault breakers or just the arc-fault in general. However, after talking to a company (Leviton, I believe), there was (and might still be) a known problem with the design that would cause certain things to make them trip, such as some of the equipment I have.

I was under the impression that loads with motors, such as a vacuum cleaner, could falsely trip the arc-fault. Companies where working on solutions, but I had never heard of any.


For what it's worth, this is what really pisses me off. I paid 2,500$ hard earned dollars....money that I made by using my skills and knowledge. It took a long time for me to save that money. We hire a PROFESSIONAL!!!! licensed electrician, known by even the inspectors that are authorized to inspect our work....they say they refuse to say anything bad about the guy because of such the fine work he does....

He's training his son. We did not know this. He should have supervised his son in training or at least fixed what I consider to be mistakes. The son must have used some sort of powered drill / driver to tighten the bolts on the breakers, buss bars, etc. They're all almost impossible to get off. Here is one picture of one that I finally got off. It shouldn't be like this.

I need to replace breakers, but some are even stripped. This one that I'm uploading, I couldn't undo with a flat head screwdriver. I had to use a rusty square bit, because the normal square bit was slipping. Thankfully, I had a rusty one that was just rusty enough to fill the holes where it was stripped a bit, and I was able to remove this one neutral wire. Look at the freaking thing! That is ridiculous!!!!!

That's a picture of one of the 12/4 with ground wires that he ran. Is that dangerous if any of the breaker wires are squashed like that? I think smaller diameter, more resistance, more heat....This is probably the reason when I turn on just the workstation, with a monitor turned on, nothing else, the GFCI receptacle he installed trips half the time. PSU is 650 watt. Grrr.