Don't kill yourself - GFI you tanks

[Saltcreep]

So according to that document code does not cover aquariums.  It only covers area's that you are washing things mainly.

That scan was from a Simplified version of the Ontario Electrical Code as it applies to houses. I can probably get a hold of the code for commercial buildings like pet shops, commercial kitchens and whatever, but I'm not sure I could lift it.

Common sense tells me that for most aquarists with one or two tanks, replacing the first duplex outlet on a circuit with a new CFCI outlet should be sufficient. For me, I had the chance to do it right the first time when we constructed the fishroom. All the tank lighting in the room is on it's own dedicated circuit, controlled by one central timer. The other electrical needs for the tanks is on another dedicated circuit. Both of these circuits are protected by GFCI breakers in the service panel. The rest of the room lighting and outlets are supplied from two other dedicated circuits. I love redundancy. There is also an 'air circuit' all around the room with outlets for each tank, but that's another story.

[Canoe]

Some points.

GFCI breakers are faster to shut off when a fault is detected. As in, better chance of that being before you, or kids, their friends or your fish are fried.

Circuit breakers shutoff on exceeding the current they're rated at. I.E., 15A is the most likely forum members will encounter.

GFCI breakers shut off when:

• current flow is detected on the Safety Ground
• the current flow in the Live and Neutral are out of balance (all the current coming through Live should be returning through Neutral)
  

The second can happen when:

• Live current from this circuit is not returning to its Neutral, but has found another path to ground or the neutral of another circuit
• Live current from another source is returning to neutral through the GFCI

Contemplate this scenario that has one GFCI protecting multiple devices.

• Two pumps (or any two VAC devices) in water a tank/sump, both are plugged into the same powerbar, which in turn is plugged into a GFCI receptacle.
• One device could develop a fault, but the easiest path for the current is to continue home through the neutral: no ground current nor Live-Neutral imbalance, the GFCI breaker does NOT trip off. Water is energized.
• If your wet hand provides a alternate path, current can flow. If that current goes to the ground to the GFCI, it will trip off. If that current goes to the Neutral, the Live-Neutral current flow is still in balance, and the GFCI will not trip off.
• If you have two fault devices, the Live from one could be flowing through the system's water and to the Neutral of the other device. No current flow on ground, balanced flow between Live-Neutral. GFCI does not trip off.

When the GFCI does not trip off, you're flowing current until the 15A breaker trips off.

Using a (one) GFCI is safer than not using it, but that does not cover all failure modes. Putting a ground probe into the tank or sump may allow an energized tank to trip the ground of the GFCI. There's debate on this, including that a tank may have small voltage/current naturally.

Giving each device their own GFCI means that their current is shut off if the current going out is not all coming back in, as in, if that single device has a fault. It will also shut of if another device has a fault and tries to ground out through this GFCI's Safety Ground or Neutral, but this shuts off the path to Ground/Neutral, it doesn't turn off the current to the faulty device, and that current will continue looking for another path to ground/neutral. That device needs to be on a GFCI too, so its current not returning through its Neutral shuts the current flow off to the faulty device.

Search for "Shock Buster GFCI"
They make a Single receptacle GFCI, for around $15 if I remember correctly.
Also good for putting a power bar on a GFCI for those that want the level of protection of a single GFCI, but don't want to replace the receptacle in the wall or the GFCI breaker in the panel.