Dedicated GFCI circuits - Mulitwire Branch or not?

[sleepydoc]

For most setups, 2 receptacles/4 outlets is plenty. Most people use outlet strips or something similar so they don't have 20 wires running out the back of their tank, and the OP said he had an Apex controller that he was using with its own energy bars, so having more outlets isn't really useful.

As far as having them in the same box goes, it's fewer holes in the wall and easier to pull the wire to one location vs 2. Having devices on more than one circuit is actually quite common and something you should be aware of if you're working on anything electrical. If you decided to do electrical work the onus is on you to know what you're doing and take appropriate precautions to protect yourself.

 

[mmn]

I had a problem when I was wiring mine. I had two ckts sharing the same conduit and when I replaced one of the breakers with a GFCI breaker there was one outlet that would trip the GFCI breaker no matter what I plugged in there. Couldn't figure out what the hey was going on.

Then I found out the receptacle had been wired with the hot on one ckt but the neutral was on the other. Since both ckts were sharing the same conduit, both ckts and their neutrals passed though the outlet box. Even though they were both wired to the same bus in the subpanel, the GFI breaker tripped until i wired the outlet with the other (correct) neutral.

Know why?

Here's the reason. A GCI breaker has terminals for both hot and neutral, and a wire that connects to the neutral bus. That's how it senses a current differential in the ckt between hot and neutral. Since that outlet was using another neutral, it worked fine as a normal outlet, but the GFCI breaker was sensing current on the hot and not on its neutral. So it tripped. As it should!

 

[salty joe]

You might consider connecting 2 or 3 GFCI wired in parallel to each circuit. I'm glad I did because every now and then I get a nuisance trip.

 

[2Quills]

I ran two circuits to my 120g system, installed gang boxes in the stand and just ran 3 gfci receptacles on each circuit wired in parallel for the redundancy factor. That way you're not loosing power on the rest of the circuit for a single failed piece of equipment or nuisance trip.

 

[Shawn O]

As far as having them in the same box goes, it's fewer holes in the wall and easier to pull the wire to one location vs 2. If you decided to do electrical work the onus is on you to know what you're doing and take appropriate precautions to protect yourself.

Yes, it is easier than having to cut two holes in the wall. It could easily be done with one box on either side of a stud without much more effort.

As far as it being the next homeowners problem to ensure there aren't two separate circuits in the same electrical box, yes it is their responsibility to check first. It is also the current homeowner's responsibility not to create a situation where someone could be injured or killed. Most people would plug a light (or some other device) into one outlet and flip breakers until the light goes out. Who would assume that the other outlets in the same box would be connected to another breaker? Two separate single-gang boxes would avoid any confusion, hazard and liability in this situation. A Personal Injury lawyer would have a field day with it, and probably win. This was my point to begin with, I may not have made that clear in my previous post, I apologize if this was the case.

 

[sleepydoc]

Dedicated GFCI circuits - Mulitwire Branch or not?

As I said, the minute you take the cover off, you are assuming the liability for your knowledge or ignorance of electrical wiring and code. 2 GFCI outlets in the same box should be a tip off to a 2nd circuit, as would the extra wires coming in. If you are assuming that all wires in a given box are on the same circuit, you really shouldn't be doing electrical work.

When I do electrical work, I make sure it's up to code. At this point there is no liability, and no hazard beyond someone's lack of knowledge and experience. I'm sure you could find a lawyer to sue if you got hurt, but if the wiring met code, any halfway competent defense lawyer would rip you to shreds in about 30 seconds.

If you feel the need to warn people, a good tip is to write the number of the circuit breakers on the inside of the outlet plate.

 

[2Quills]

The circuits would need to be cut simultaneously with a tie-bar per code if they are in the same gang box. Just do that and you'll be fine. Pull 2 12/2 romex cables to the same box and you will have your redundancy.

FWIW, anyone who sticks their hands in any gang box without first checking to see if there is anything hot is asking for trouble.

Mark them with different colored electrical tape and or label the cover.

.02

 

[dkeller_nc]

The circuits would need to be cut simultaneously with a tie-bar per code if they are in the same gang box.

Yep - industrial code requires this, as well as labeling. Which is an excellent reason not to do it - you don't want all of your electrical power to your tank tripping simultaneously on one GFCI nuisance fault.

Another reason to go to the effort of putting in two outlet enclosures is so that you can wire one of them with a inverter/charger and a battery backup. You then have automatic backup power to at least some of the tank's circulation if you're away when the power goes out, as well as allowing the much, much less expensive addition of a manual-start, manual hook-up small generator to ensure that an ice storm/hurricane/wind storm doesn't kill everything instead of a whole house generator with automatic start and an automatic transfer switch.

 

[2Quills]

Yep - industrial code requires this, as well as labeling. Which is an excellent reason not to do it - you don't want all of your electrical power to your tank tripping simultaneously on one GFCI nuisance fault.

Another reason to go to the effort of putting in two outlet enclosures is so that you can wire one of them with a inverter/charger and a battery backup. You then have automatic backup power to at least some of the tank's circulation if you're away when the power goes out, as well as allowing the much, much less expensive addition of a manual-start, manual hook-up small generator to ensure that an ice storm/hurricane/wind storm doesn't kill everything instead of a whole house generator with automatic start and an automatic transfer switch.

Losing all power would only be an issue if he used a dual pole gfci breaker or was sharing the same common. Other wise the dual pole breaker shouldn't trip if he was using gfci receps in the box barring any actual short between the two circuits.

 

[Shawn O]

If you feel the need to warn people, a good tip is to write the number of the circuit breakers on the inside of the outlet plate.

Makes sense and a good tip.