Lesson Learned - make sure your A/C circuit is properly grounded

[Joe]

If you're getting a tingling sensation (shock) when you have your hands in your sump/DT the problem may not be your equipment, it might be the A/C circuit itself.

I thought I should post my experience in case anyone else is having the same problem - it has taken me a couple of months to solve this mystery...

A few months ago I noticed that I was getting a mild shock when I had my hands in my sump. I quickly determined that the source was my ECO633 return pump. I concluded that the problem must be that the pump is defective so I bought a new one. When I plugged in the new pump, the tingling sensation was not present. Problem solved, so I thought.

Just yesterday I was doing a water change and when I was finished I plugged my return pump back in (the new ECO633) and sure enough, I was getting shocked again. Needless to say, I was not the least bit happy. I figured it was highly unlikely that I had two defective pumps, so I started exploring my wiring. It turned out that the A/C circuit I had been using for my tank was not properly grounded. The ECO pump was the only submerged piece of equipment I had with a 3-pronged (grounded) plug. Since the pump was not getting grounded through the A/C circuit, it was grounding itself through the water. I installed my equipment on a different A/C circuit (that is properly grounded) and there is no more tingling when I reach into my sump.

[Hookup]

Thanks for posting this.  Pretty scary, and good troubleshooting.... 

[FishBuddy]

This is a value piece of equipment that all of us should have handy.  They are around $4 when it was on sale:

http://www.princessauto.com/pal/product/8003373/Pvc/AC-Receptacle-Tester

Also, since we are in the fish hobby, we always deal with electrical equipment close to water; a deadly combination!
Therefore, your AC receptacle should always be a GFCI-type.  It's a very cheap investment and could save you or your family's lives.  Use this tester to test your GFCI receptacles:

http://www.canadiantire.ca/AST/browse/6/Tools/2/Electrical/ElectricalTesters/PRD~0520027P/Gardner-Bender+GFI-3501+GFCI+and+Receptacle+Tester.jsp?locale=en

Once again, if you are getting it on sale, it's around $6.

I have a few of these in the house and I often (once a month) test out my existing receptacles for faults.

[Greatwhite]

This is a prime example of why people shouldn't be messing with electrical themselves without "proper" training.  I admit that I am guilty of running wires/plugs/etc and I'm no electrician.  But I do have a basic understanding of how it works - and how to properly install a plug.

The GFCI recommendation is good, however -- don't take this advice too literally.  If you have 2 aquariums on one circuit on opposite ends of the room, you need to determine which of the 2 plugs is first in the series - and THAT one should be GFCI.  Just because the other plug is beside water does not make it necessary to GFCI it.  The first plug in the circuit being GFCI protects the other plugs.

This is why in most houses, you'll find a GFCI plug in a powder room, and the other bathrooms in the house are standard plugs on the same circuit.  I have a GFCI plug in my garage, and the outside plugs are covered by it. 

If you have 2 GFCI plugs on one circuit, they will interfere with each other and will pop each other continually.  An electrician explained it to me in big words...  The jist of it was "don't do it".

[lucius]

I was reading up on gfci plugs and they also say to not install them if their is a device with a motor because when the motor turns on, it would cause a spike and the gfci would go off.  For my place, the builder ran one electrical line throughout my basement and I have an HRV, tankless water heater and fish tanks all on the same circuit.  So I may have to run a dedicated line one of these days for my fish tanks.

[FishBuddy]

This is a prime example of why people shouldn't be messing with electrical themselves without "proper" training.  I admit that I am guilty of running wires/plugs/etc and I'm no electrician.  But I do have a basic understanding of how it works - and how to properly install a plug.

The GFCI recommendation is good, however -- don't take this advice too literally.  If you have 2 aquariums on one circuit on opposite ends of the room, you need to determine which of the 2 plugs is first in the series - and THAT one should be GFCI.  Just because the other plug is beside water does not make it necessary to GFCI it.  The first plug in the circuit being GFCI protects the other plugs.

This is why in most houses, you'll find a GFCI plug in a powder room, and the other bathrooms in the house are standard plugs on the same circuit.  I have a GFCI plug in my garage, and the outside plugs are covered by it. 

If you have 2 GFCI plugs on one circuit, they will interfere with each other and will pop each other continually.  An electrician explained it to me in big words...  The jist of it was "don't do it".

Yes, I do agreed that unless you know exactly what you are doing, it's best to hire an electrician to do the work for you.  Don't mess around with it... 

As for the GFCI receptacle, where you install *does* matters.  As indicated by you, I had mine installed in the first receptacle on the chain.

[Greatwhite]

I was reading up on gfci plugs and they also say to not install them if their is a device with a motor because when the motor turns on, it would cause a spike and the gfci would go off.  For my place, the builder ran one electrical line throughout my basement and I have an HRV, tankless water heater and fish tanks all on the same circuit.  So I may have to run a dedicated line one of these days for my fish tanks.

When I spoke to an electrician, and he explained the GFCI limitations, it was when I was asking about adding another plug in my bathroom.  He said that it would be OK as long as we weren't planning on running 2 hair dryers simultaneously...  The overall wattage of 2 hair dryers would pop the GFCI for sure.  I'm sure it is the spikes of turning the hair dryers on and off that would cause the popping...

[Joe]

The receptacle tester is an excellent idea - it would have saved me much troubleshooting time.

...and just for the record I wasn't the one who wired the faulty circuit (house came that way).

[Greatwhite]

...and just for the record I wasn't the one who wired the faulty circuit (house came that way).

Oh, I believe that.  Everyone's a handy man -- and then to move to avoid possible issues with their work.

[Canoe]

... The first plug in the circuit being GFCI protects the other plugs...

While subsequent devices down the line are "protected", and this is commonly done and thought to be good protection, using a single GFCI to protect multiple devices leaves a huge hole in the protection, while falsely leaving one feeling safe.

A GFCI is supposed to detect current flowing on the safety ground and this triggers the power off, which, as expected, in turn removes power for all devices plugged into it. Additionally, modern GFCI receptacles will also detect an imbalance between the current going "out" on the live wire vs. the current coming back "in" on the neutral wire, and will trigger off when an imbalance between them is detected, be it current it supplied not returning, or extra current coming back from somewhere else. (NOTE: in fact, the GFCI breakers I've installed do not detect any current on the safety ground - they only compare the live and neutral for balance; it may be that some GFCI receptacles or adapters do the same)

Therefore:

• A single device plugged into a GFCI: if that device has a fault that allows its current to go elsewhere, even to an entirely different circuit, the current going out of the GFCI doesn't match the current returning and the GFCI will trigger off (without requiring that the stray current be returned for detection on its safety ground).
• But where multiple devices are powered and "protected" by a single GFCI, that will not protect against stray current from a faulty device that returns through the neutral of another device that is "protected" by that same GFCI - the total current out compared with the total current returning balances and the GFCI does not trigger off. This means you can have a fault in one, or more, of your multiple devices that can remain undetected by that single GFCI, and the faulty device can remain powered, with its stray current fault energizing one or more devices, or even the water, waiting for you or your kids to come along and touch something...

Solution:

• 1. With a single GFCI on the front end, a ground probe in the tank (and sump?) will provide a path for stray current that faults into the water, and with that ground probe plugged into the circuit that stray current will be detected by the GFCI and it will trigger off. Some think this is sufficient, but this only works when the ground probe is the only or best path to ground, and therefore cannot always protect against the situation detailed above.
• 2. For full protection, every electrical device in contact with the water needs to have its own GFCI. This method means that any fault in any device thus protected will be detected and its power shut off. Detection as to the source of the fault is easy, as you can see which GFCI has triggered off. This can be done with plug-in GFCI adapters, or you can wire up a number of GFCI receptacles to make your own multi-GFCI power bar (assuming you know how to do such electrical work safely).
  
• 3. One view is to also have any device that may fall into the water have its own GFCI, but I believe that adding solution #1 to solution #2 addresses devices that may fall into the water.