Stray Voltage
- Thread starter Tamw1se
- Start date
A grounding probe is a great idea and it is my thought that every tank should have one but its only a mask.
Figure out what is causing the issue and either keep an eye on it or replace it. .001 leads to .002 and so on. Not a big deal today turns life threatening somewhere down the road.
Also make sure it isn't just feeding back through the ground. If you unplug everything and still have a reading you know this is happening and not a lot you can do about it.
Figure out what is causing the issue and either keep an eye on it or replace it. .001 leads to .002 and so on. Not a big deal today turns life threatening somewhere down the road.
Also make sure it isn't just feeding back through the ground. If you unplug everything and still have a reading you know this is happening and not a lot you can do about it.
LiquidCache
New member
What brand multimeter are you using? Take into account that even a high end Fluke will have a variance of .05%. You're talking about .001, that's one thousandths of a volt.
aguila88psi
Zoa Addict
Also check your units, .001MV is 1V and 1000mV
BlueCoast
New member
This, and keep in mind the method that most multimeters(read meters we can afford up to a few hundred dollars) use a complex calculation to measure the voltage. There is some math involved that usually amplifies any errors.
Bottom line, don't trust the mutlimeter.
Secondly, read up on induced voltage, this is more likely what you are seeing. ALL electronics emit EMI, water absorbs that and shows a very small voltage reading. This does not mean you have pumps leaking electricity.
One way to think of this is birds on power lines, as long as they do not ground themselves, they do not get shocked. Yes, they are at the same electrical potential as the power line, but no damage occurs until they act as a ground and KV of CURRENT pass through them turning them into a smoking mess.
I personally am against ground probes, you are providing a nice path to ground to turn any induced voltage into induced current.
Get a GFCI outlet and be done with it. It offers MUCH better protection than a ground plug that relies on the circuit breaker to trip. GFI's trip in the 4-6 milliamp range(leaked current), breakers don't trip until 15,000-20,000 milliamps are pushed through.
Does your bathtub have a ground probe or a GFCI outlet?
LiquidCache
New member
+1 to the above.
ganjero
saiperchémibatteilcorazon
This should help (from user beananimal)
"attempting to measure voltage in your aquarium is somewhat meaningless. What we are concerned with is current flow. Measuring a floating voltage with a handheld meter is not going to give you an accurate view of the situation and the reading will depend on numerous factors, but mostly the impedance of the meter and that of the source voltage. Measuring current however, is straight forward and will give a better picture of what is going on in the system.
That said, even the current measurements can be suspect, as the meter impedance has to compete with other ground paths (pumps shafts for example) in the tank. Remember, electricity does not take the path of least resistance, it takes all paths in proportion to their resistance.
Moving forward:
Your assessment of ground probes is fairly decent with regard to the CONS associated with them but your advice with regard to electrical service grounding has some faults (no pun) in it.
While I am not going to advise against code, I will say that numerous studies have shown that most ground rods are as good as useless at providing a true earthed connection. The connection to the cold water pipe is MUCH better, but in many cases is also as good as useless. The only ground reference that we can really count on to clear a fault is the center tap on the pole that we bond our ECG to! I still drive my two ground rods and bond to the cold water inlet, as it can't hurt to try to earth the connection....
Testing for ZERO voltage between the ECG and NEUTRAL at the receptacle can be misleading. If we do get a reading, then we still need to determine of we have a poor bond at the main panel, a fault somewhere upstream or induced voltage/current due to proximity to other fixtures. Again, meters can lie based on their input impedance and what they are connected to.
In any case you have actually overlooked the MOST IMPORTANT consideration when installing a grounding probe in an aquarium: ALL of the devices connected to the aquarium really MUST be GFCI protected. Adding the grounding probe to the aquarium introduces fault scenarios that do not exist without the probe. That is, GFCIs are important, but you should NEVER run a grounding probe WITHOUT full GFCI protection of the equipment in or around the aquarium.
The easiest example to illustrate the danger introduced by the ground probe is an aquarium with a light fixture where salt creep energizes an ungrounded reflector. There are dozens of OEM and DIY fixtures that utilize ungrounded reflectors.
In a setup without a ground probe, a person leaning into the tank and also touching the reflector will not likely get shocked, as there is no path for the current to flow. The reflector stays happily energized but is insulated from ground through the high impedence of your body and the ungrounded tank water.
In a setup with a ground probe, a person leaning into the the tank and also touching the reflector creates a path to ground from the fixture, through their body and into the tank water that is grounded. If there is a GFCI, then it will trip. If there is NOT a GFCI then shock or electrocution is immanent."
More from him, if you have the time is a good read http://www.beananimal.com/articles/electricity-for-the-reefer.aspx
"attempting to measure voltage in your aquarium is somewhat meaningless. What we are concerned with is current flow. Measuring a floating voltage with a handheld meter is not going to give you an accurate view of the situation and the reading will depend on numerous factors, but mostly the impedance of the meter and that of the source voltage. Measuring current however, is straight forward and will give a better picture of what is going on in the system.
That said, even the current measurements can be suspect, as the meter impedance has to compete with other ground paths (pumps shafts for example) in the tank. Remember, electricity does not take the path of least resistance, it takes all paths in proportion to their resistance.
Moving forward:
Your assessment of ground probes is fairly decent with regard to the CONS associated with them but your advice with regard to electrical service grounding has some faults (no pun) in it.
While I am not going to advise against code, I will say that numerous studies have shown that most ground rods are as good as useless at providing a true earthed connection. The connection to the cold water pipe is MUCH better, but in many cases is also as good as useless. The only ground reference that we can really count on to clear a fault is the center tap on the pole that we bond our ECG to! I still drive my two ground rods and bond to the cold water inlet, as it can't hurt to try to earth the connection....
Testing for ZERO voltage between the ECG and NEUTRAL at the receptacle can be misleading. If we do get a reading, then we still need to determine of we have a poor bond at the main panel, a fault somewhere upstream or induced voltage/current due to proximity to other fixtures. Again, meters can lie based on their input impedance and what they are connected to.
In any case you have actually overlooked the MOST IMPORTANT consideration when installing a grounding probe in an aquarium: ALL of the devices connected to the aquarium really MUST be GFCI protected. Adding the grounding probe to the aquarium introduces fault scenarios that do not exist without the probe. That is, GFCIs are important, but you should NEVER run a grounding probe WITHOUT full GFCI protection of the equipment in or around the aquarium.
The easiest example to illustrate the danger introduced by the ground probe is an aquarium with a light fixture where salt creep energizes an ungrounded reflector. There are dozens of OEM and DIY fixtures that utilize ungrounded reflectors.
In a setup without a ground probe, a person leaning into the tank and also touching the reflector will not likely get shocked, as there is no path for the current to flow. The reflector stays happily energized but is insulated from ground through the high impedence of your body and the ungrounded tank water.
In a setup with a ground probe, a person leaning into the the tank and also touching the reflector creates a path to ground from the fixture, through their body and into the tank water that is grounded. If there is a GFCI, then it will trip. If there is NOT a GFCI then shock or electrocution is immanent."
More from him, if you have the time is a good read http://www.beananimal.com/articles/electricity-for-the-reefer.aspx
