Stray Voltage

[tmz]

There is no doubt that a gfci is a critical but not always sure protection.

Some common problems:

(1)The gfci may trip in a minor event such as a ballast firing or a powerhead with a faulty start and leave a whole system shut down.Installing separtate gfci circuts is costly and difficult.

However, using multiple gfcis , thus isolating the circuitry for individual or multiple pieces of equipment is easy . There are plug in type gfcis available for less than $10. Power strips can be plugged into them and individual pieces of equipment or a group can easily be placed on a separate circuit this way.

(2)Reef lighting and pumps usually come with a grounded plug as do any electrical devices with a casing that is not insulated (usually metal).This is because the casing needs to be grounded in case of a sort within the device from a loosened wire,salt creep,etc. allowing electrical contact with the casing. Basic timers for household lighting don't have a ground receptacle, so tank lighting and pumps often go through an adapter plug and are used ungrounded.

This is very dangerous. Only use timers with a grounding receptacle,typically sold as"heavy duty ' and only use outlets with a ground for that matter.

Heaters are a special concern. They are usually not equipped with a grounding plug since the casing is insulated. When a seal leaks or the glass cracks,however, the arc noted by Jdiek a few posts back may occur failing to trip a circuit, even a gfci . They need to be placed very carefully out of harm's way . Some advocate replacing them periodically. I will be looking into afci devices at least the heaters on my system.

 

[Rickyrooz1]

If that's the case than my TEK II T5 retrofit is causing the problem. Whenever I lean over the light my arm sometimes touches the reflector while my hand is in the water and I get shocked. I think it's due to the T5 light not being correctly grounded unless the light is acting as a ground probe for the tank. Any thoughts? When I had the light plugged in I got a reading of 1.8 instead of 0.3 without the light at ACV 200.

 

[jdieck]

Re: Re: Re: Most of you are wrong.

Re: Re: Re: Most of you are wrong.

<a href=showthread.php?s=&postid=15097067#post15097067 target=_blank>Originally posted</a> by narwal
So the most safe installation for you is to have breaker, GFCI and grounding probe, All faults with exception of some sparking situations which require an AFCI will be detected and protected against. This is of course implying that the GFCI is tested from proper functioning at least once a month.

>>>EXACTLY. THANK YOU. PROBE AND GFI. I have to assume that no one is running a fuse box with penny instead of a fuse.

The second safest ...............<snip>

>>>Sorry, I had to cut the rest. When it comes to safety it has to be done properly. Second or third choices are not acceptable.

Thanks for your input.

Many of the points stated in your post IMO are not valid but I do not want to keep on confusing the heck out of everyone.
Just want to say that I do understand how a GFCI (and all other electrical equipment) works and also that as far as there is agreement of not installing a probe by itself without a GFCI I will leave it at that.
Good discussion though.

 

[tmz]

<a href=showthread.php?s=&postid=15097210#post15097210 target=_blank>Originally posted</a> by Rickyrooz1
If that's the case than my TEK II T5 retrofit is causing the problem. Whenever I lean over the light my arm sometimes touches the reflector while my hand is in the water and I get shocked. I think it's due to the T5 light not being correctly grounded unless the light is acting as a ground probe for the tank. Any thoughts? When I had the light plugged in I got a reading of 1.8 instead of 0.3 without the light at ACV 200.

This happened to me a years back when I had a grounding probe in the tank,no gfci and a fault in the ground for the light fixture. When I removed the probe from the tank and brushed my arm on the light while my hand was in the water ,there was no shock. So obviously the tank was insulated. When the tank was grounded with a probe , however, my arm provided a way to ground, linking the light fixture to the grounded water.. Luckily, it was one arm. If I had one hand in the water and touched the light with my other arm, the current would have passed my chest with likely dire consequences. This is an example , where having a probe without a gfci can be very hazardous.

A reading of 1.8 volts could just be induced voltage but if you are getting zapped you have some amperage.

 

[narwal]

<a href=showthread.php?s=&postid=15097145#post15097145 target=_blank>Originally posted</a> by tmz
There is no doubt that a gfci is a critical but not always sure protection.

Some common problems:

(1)The gfci may trip in a minor event such as a ballast firing or a powerhead with a faulty start and leave a whole system shut down.Installing separtate gfci circuts is costly and difficult.

A GFI does not trip on account of overcurrent situations, only imbalances.

 

[narwal]

Re: Re: Re: Re: Most of you are wrong.

Re: Re: Re: Re: Most of you are wrong.

<a href=showthread.php?s=&postid=15097573#post15097573 target=_blank>Originally posted</a> by jdieck
Many of the points stated in your post IMO are not valid but I do not want to keep on confusing the heck out of everyone.
Just want to say that I do understand how a GFCI (and all other electrical equipment) works and also that as far as there is agreement of not installing a probe by itself without a GFCI I will leave it at that.
Good discussion though.

They are not only valid but correct. That is why we design and install electrical systems according to a safety CODE, not according to "opinion".

All circuits require overload protection, fault protection, and grounding. Ergo - a fuse or breaker/a GFI/and a ground.

 

[narwal]

<a href=showthread.php?s=&postid=15098078#post15098078 target=_blank>Originally posted</a> by tmz
This happened to me a years back when I had a grounding probe in the tank,no gfci and a fault in the ground for the light fixture. When I removed the probe from the tank and brushed my arm on the light while my hand was in the water ,there was no shock. So obviously the tank was insulated. When the tank was grounded with a probe , however, my arm provided a way to ground, linking the light fixture to the grounded water.. Luckily, it was one arm. If I had one hand in the water and touched the light with my other arm, the current would have passed my chest with likely dire consequences. This is an example , where having a probe without a gfci can be very hazardous.

The fact that you didn't get a shock when you took out the probe confirms the problem. You didn't get a shock because you and the tank were insulated. This only proves that you need to ground it AND make sure the fixtures are also properly wired. By touching the fixture and the water with the probe in the tank YOUR BODY completed the circuit. If the light was properly grounded you would not have gotten a shock, and if subsequently something happened like water or moisture caused a short, the current would have flowed through the probe instead of through you, taking the path of least resistance.

This is the whole point of proper grounding - to direct stray current away from people and fish and discharfe safely to ground.

The very important lesson to learn from this is that ALL EQUIPMENT must be properly grounded. If the light was properly grounded the current would have flowed through it's ground circuit and not you or the tank or the probe in the tank. If the current was high enough it would have tripped a breaker unless you had a GFI on the circuit which would have tripped first.

Another concept we haven't mentioned is that the ground MUST BE COMMON to all devices. This is almost always the case, but there are situations where something might be connected to an isolated ground. Without getting too technical you can design a circuit which has a ground for protection, but is isolated from the other circuit or common ground.

You see this a lot in computer room installations. It's a way to protect sensitive equipment from surges when there is a short to ground somewhere else. There are receptacles which are orange colored specifically to indicted isolated ground. In such a design you would see that there is zero continuity between the ground on that receptacle and the ground on another, non-isolated or common ground receptacle.

Fascinating, eh?

 

[tmz]

<a href=showthread.php?s=&postid=15098238#post15098238 target=_blank>Originally posted</a> by narwal
A GFI does not trip on account of overcurrent situations, only imbalances.

I know that.

 

[tmz]

"The fact that you didn't get a shock when you took out the probe confirms the problem. You didn't get a shock because you and the tank were insulated". posted by norwall

I'm confused.

"The only way for it not to be grounded would be if the tank had nothing connected to it which plugs in, AND it was sitting on a try insulated base. "posted by norwall.

Since my tank has many devices plugged in that are plugged in it etc. Rather typical actually. Which of your above statements is correct?Is it insulated or grounded? I believe tanks are insulated. Of course there may be exceptions.

The point remains that hobby lighting fixtures often have shorts and loose wiring which when coupled with a grounding problem and a grounding probe in the tank without a gfci can lead to severe shock and possibly death.No probe = no ground unless you are standing in a puddle or otherwise grounded.

Grounding not only directs stray current(amperage) it creates it from stray voltage.

How do you account for leaking heaters?

 

[tmz]

Ok Common ground? My guess is voltage will flow as current(amperage) by the shortest route to ground. So , if there is more than one gounding path,current may flow from probe to probe through the tank by whatever is the shortest route with the least resistance.

 

[narwal]

<a href=showthread.php?s=&postid=15098580#post15098580 target=_blank>Originally posted</a> by tmz
"The fact that you didn't get a shock when you took out the probe confirms the problem. You didn't get a shock because you and the tank were insulated". posted by norwall

I'm confused.

"The only way for it not to be grounded would be if the tank had nothing connected to it which plugs in, AND it was sitting on a try insulated base. "posted by norwall.

Since my tank has many devices plugged in that are plugged in it etc. Rather typical actually. Which of your above statements is correct?Is it insulated or grounded? I believe tanks are insulated. Of course there may be exceptions.

The point remains that hobby lighting fixtures often have shorts and loose wiring which when coupled with a grounding problem and a grounding probe in the tank without a gfci can lead to severe shock and possibly death.No probe = no ground unless you are standing in a puddle or otherwise grounded.

Grounding not only directs stray current(amperage) it creates it from stray voltage.

How do you account for leaking heaters?

Yes, it's confusing.

Insulation means that you or the tank are totally isolated from everything, including ground. Grounded means that there is a path to ground.

If you could be absolutely sure that the tank is isolated from ground AND you are not grounded then you would be like the bird sitting on the power line - no chance of shock. But there are too many variables to risk it. Just moisture on a power cord could create a path to ground, although not likely a very good one. This is where the ground probe steps in and provides a very good path to ground.

Given all the possibilities isolation is not a good strategy.

You should see what it's like in a huge transformer vault. There is so much current that just the air can become conductive enough to cause an arc. Like lightening. When the open it up and get ready to change out a transformer or mains breaker you can feel it 10 feet away. Makes your hair stand up. That's when I leave. It can jump through the air. The guys have to wear so much rubber they look like the Michelin tire guy.

 

[tmz]

Sounds like a scene from ghostbusters.lol

 

[narwal]

<a href=showthread.php?s=&postid=15098580#post15098580 target=_blank>Originally posted</a> by tmz
.

Grounding not only directs stray current(amperage) it creates it from stray voltage.

How do you account for leaking heaters? [/B]

NOTHING "creates" current. You need to review Ohm's Law.

http://en.wikipedia.org/wiki/Ohm's_law

You also posted: "Ok Common ground? My guess is voltage will flow as current(amperage) by the shortest route to ground. So , if there is more than one gounding path,current may flow from probe to probe through the tank by whatever is the shortest route with the least resistance."

The flow of current is ALWAYS along the route of least resistance, measured in nominal impedance or OHMS, regardless of length. Of course, two wires with the same impedance/foot will have impedances proportional to their lenghts. When installing speakers you want to keep the impedance of the wire less than 10% of the nominal impedance. So for an 8ohm speaker you want the wire to contibute less than. 0.80 ohms to the circuit.

We do this by measuring the propose speaker run then using speaker wire which will add no more than 10% of the impedance
to the circuit. Values for various composition of wire and guages is easily found. Of course, less is better, but you have to factor in cost and and the difficulty and aesthetics of running huge diameter wires.

"How do you account for leaking heaters?"

Heaters always worry me. They are pretty high current and intuitively seem dangerous, especially the totally submersible ones. All you can do is handle them gently and take the precautions previously discussed.

I'm especially suspect of the seal between the temperature adjustment knob and the heater. I only use fully submersible heaters and I don't fully submerse them. I mount them so that the water level does not go up to the top assembly but stays on the glass tube.

 

[tmz]

OK perhaps grounding doesn't "create" current(amperage) it converts voltage to it which was my meaning. Without a ground the electrons don't move and there is no harmful amperage.


"The flow of current is ALWAYS along the route of least resistance, measured in nominal impedance or OHMS, regardless of length. Of course, two wires with the same impedance/foot will have impedances proportional to their lenghts. When installing speakers you want to keep the impedance of the wire less than 10% of the nominal impedance. So for an 8ohm speaker you want the wire to contibute less than. 0.80 ohms to the circuit.

We do this by measuring the propose speaker run then using speaker wire which will add no more than 10% of the impedance
to the circuit. Values for various composition of wire and guages is easily found. Of course, less is better, but you have to factor in cost and and the difficulty and aesthetics of running huge diameter" psoted by narwal

How does that differ if at all from:

"Ok Common ground? My guess is voltage will flow as current(amperage) by the shortest route to ground. So , if there is more than one grounding path,current may flow from probe to probe through the tank by whatever is the shortest route with the least resistance." posted by me

A gfci wont protect you against a faulty heater ;will it?

 

[narwal]

Properly grounded equipment (which includes a ground probe), which is all connect to a GFI protect circuit in will provide maximum protection.

 

[tmz]

But not necessarily a faulty heater?

 

[narwal]

Fawlty Heater

Fawlty Heater

<a href=showthread.php?s=&postid=15101060#post15101060 target=_blank>Originally posted</a> by tmz
But not necessarily a faulty heater?

Yes.... it SHOULD.

Nothing is absolutely certain, but if all your equipment is properly grounded, plugged into a GFI protected circuit, and you have a ground probe correctly installed you should not have a problem.

The reason I say "should" is that there is no way to predict how quickly the protection will kick in. Even a simple appliance connected only to a breaker should trip the breaker in an overcurrent situation. But we can't say for sure if this will happen quickly enough to prevent wires from overheating and melting, or a spark which could cause a fire. The breaker WILL trip. The question is how quickly.

Don't agonize over this. Between the circuit breaker, a ground probe and GFI protection you have done all you possibly can and you shouldn't have any problems.

In my experience you have more to fear from infections, bad water chemistry and some drunk pouring his Mojito into your tank than anything else. Oh yeah...overfeeding is a killer too.

 

[billsreef]

Re: Fawlty Heater

Re: Fawlty Heater

<a href=showthread.php?s=&postid=15101393#post15101393 target=_blank>Originally posted</a> by narwal
Yes.... it SHOULD.

Nothing is absolutely certain,

That is the bottom line. By all means, it is wise to use protection when mixing electricity and water. However, don't let in lull you into a false sense of security. I've seen mildly leaky heaters trip GFCI's, and I've also seen completely broken ones still with current going and creating bubbles from electrolysis :eek1: Bottom, line always be careful

 

[narwal]

Re: Re: Fawlty Heater

Re: Re: Fawlty Heater

<a href=showthread.php?s=&postid=15102378#post15102378 target=_blank>Originally posted</a> by billsreef
That is the bottom line. By all means, it is wise to use protection when mixing electricity and water. However, don't let in lull you into a false sense of security. I've seen mildly leaky heaters trip GFCI's, and I've also seen completely broken ones still with current going and creating bubbles from electrolysis :eek1: Bottom, line always be careful

Exactly!
We need to do this the for the same reasons you don't smoke at the gas pumps or hold fireworks in your hand. :rollface:

 

[Mike31154]

Re: Most of you are wrong.

Re: Most of you are wrong.

<a href=showthread.php?s=&postid=15094700#post15094700 target=_blank>Originally posted</a> by narwal
Sorry, but many of the comments posted here are just wrong. One needs to understand how electricity behaves and what a ground and GFI do.

Some of the silly comments:

"Grounding probe is NOT a MUST, GFCI is not either, but a GFCI has the potential of saving your life, not sure I'd have the same confidence in a grounding probe."

Totally wrong on both counts. But then - why would you say a GFI is not a must but it has the potential to save your life?

Yes, silly and wrong perhaps presented out of context the way you quoted only part of my post. In your haste to deem some of our comments wrong or silly, you've omitted some of the key information presented. I do use GFCIs by the way but not a grounding probe. I also realize that even a GFCI may be faulty and is no absolute guarantee. That's why I make every effort to keep the electrical equipment I have out of and away from the water. Heaters are the only items I haven't been able to isolate from the water. Here once again is the remaining info in my original post.

"The less equipment with power cords you have physically submerged in your system, the safer. VorTech powerhead, cord outside (or closed loop for water movement), external return pump, cord outside. That leaves the heater(s) and you can do a lot in that regard by not submerging the control head of any heater, even the "fully submersible" ones. Keep the cord above water."

So if there is no electrical cord or piece of electrical equipment physically touching the water, why would either a grounding probe or a GFCI be necessary? If you could run your system as I've highlighted above, but without a heater, that would be the situation and there would in fact be little requirement for grounding probes and GFCIs. The only thing that may put a voltage potential into your tank water may be some induced voltage from fluorescent lighting and that shouldn't be enough to be a safety concern.