Is this electrical wiring done right?

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E

Eric_yang

0
Jun 6, 2016
54
San Jose
Hi Folks,

Not sure if this is the right place to discuss...

I ordered a robot cleaner which needs a power from the power center box. A licensed contractor installed a GFCI outdoor receptacle from the power center. The robot was plugged to the GFCI receptacle; it worked fine so far.

I opened up the power center a few months later and noticed that the GFCI’s supply side was wired such that its Neutural and GND pings tied together and short to the GND bar inside the power center. See the attached photo for details. I guess the reason he did this was that inside the power center it’s mainly 240V, provided by the L1 and L2 from the main breaker box. And due to some reason there’s no neutural wire from the supply side. Thus, to get 120V, the easiest way is to tie the GFCI’s N to the grounding tab inside the power center.

Such an implementation causes a concern though. As the grounding bar directly shorts to the metal housing of the power center, isn’t there a chance that the whole power center housing gets energized as it’s actually serving as the neutral for the GFCI. It seems to me the implementation increases the chance of electrocute when one touches the housing’s exposed metal as the human body serves as a parallel path to return to the main breaker box.

I think the correct way to do this is fishing the neutral wire from the house breaker box into the power center, then connects to the N of the GFCI. And GFCI’s GND ties to the grounding bar. Thus the GFCI ‘s N and GND is separated and only shorts together at the very far end in the house breaker box.

Contacted my contractor and he said it’s fine. He said the N and GND is tied together anyways and it doesn’t matter. Any thoughts?
 

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You are correct and your contractor is wrong. What he did is against code and potentially dangerous. Don’t argue with him, just bring in a qualified electrician to fix it.

And I think with the neutral and ground tied together your GFCI will not sense a ground fault properly.

Bring in someone else to pull a neutral line to the subpanel and outlet.

Why separate the ground bar from the neutral bar in a sub-panel? - E&S Grounding
 
Agreed, fishing a neutral wire is the right answer. I'm pretty sure that code required a neutral wire to a pool sub-panel even 20 years ago. And current code requires a 110v convenience gfci outlet be placed near the pool equipment which definitely requires a neutral wire. Does the test button trip when you push it?
 
Better to test the GFCI with a circuit tester. The TEST button will not tell you it is wired correctly. For $10 every house should have one. Get the one with a test button that creates a ground fault to confirm proper operation of a GFCI. I will bet it will show Erics outlet is not correct.

Klein Tools GFCI Receptacle Tester-RT210 - The Home Depot
 
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I did some more reading on this situation. I think the GFCI will work properly and test properly.

The risk and the reason it is against code is the following:

- If something is plugged into the outlet and running then the ground line is HOT
- If an electrician goes to work on the main panel and disconnects the ground wire coming from the sub panel he will think that disconnected ground wire is safe to touch.
- In fact that ground wire is HOT and the electrician can get shocked or killed

That is what makes that condition unsafe and against code. There are other failure modes with the ground wire hot that can energize other areas in the house.

Bottom line, while it may work it should not be done that way. Your contractor should have known better.
 
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Yes the test button trips GFCI. I think the GFCI only detects the imbalancing current downstream at the load side. It doesn’t care how the upstream is provided.

pooldv said:
Agreed, fishing a neutral wire is the right answer. I'm pretty sure that code required a neutral wire to a pool sub-panel even 20 years ago. And current code requires a 110v convenience gfci outlet be placed near the pool equipment which definitely requires a neutral wire. Does the test button trip when you push it?
Click to expand...
 
ajw22 said:
You are correct and your contractor is wrong. What he did is against code and potentially dangerous. Don’t argue with him, just bring in a qualified electrician to fix it.

And I think with the neutral and ground tied together your GFCI will not sense a ground fault properly.

Bring in someone else to pull a neutral line to the subpanel and outlet.

Why separate the ground bar from the neutral bar in a sub-panel? - E&S Grounding
Click to expand...

Wow! This guy is dangerous. I agree with Allen and others. This should never be done inside an electrical box.
 
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SetSailSoon nailed it! I would also say if your "electrician" does not know this, he is probably not, in fact, an electrician.

Why separate the ground bar from the neutral bar in a sub-panel? - E&S Grounding

The difference between a ground wire and neutral wire is often misunderstood. The problem primarily comes from the inappropriately named “neutral” wire. There is nothing neutral about a neutral wire. It is a current-carrying conductor, just like a hot wire and has all the potential for danger and should be treated with the same respect.

Consider the schematic for a flash-light. Your typical flashlight consists of a battery, a switch, a few wires, possibly a fuse, and a light bulb. Let’s ignore the switch, as it doesn’t relate to the point we are trying to make. In a flash light without a switch, you would see a black wire running from the battery to the light bulb, and a white wire running back from the light bulb to the battery. The black wire would represent the “hot” wire, and the white wire would be our “neutral”. The green ground wire would be tied to the metal case of the flash light and bonded to the battery return terminal via a fuse, and would be an open in regard to the rest of the circuit.

If you were to take a multi-meter and make a few measurements, you would see that the black wire has maximum amperage, and maximum voltage. The white wire has maximum amperage, and minimum voltage. The green ground wire would have minimum voltage and minimum amperage. The important thing to note, is that the white wire has the same amperage as the black wire.

Now, the white wire will have minimum voltage, until you add another light bulb to the circuit. If you cut the white wire in half, and inserted a second light bulb, the first half of the white wire would now both maximum current and half the voltage. The second half of the white wire (the piece tied to the battery) would have maximum amperage and minimum voltage. This could go on for as many light bulbs as we want to add into the circuit. Any resistance added to the white “neutral” wire, will instantly become part of the circuit and see voltage. The green ground wire would only come in to play if the black or white wire were to accidentally come in contact with the case. The electricity would short to the case and travel back to the battery causing a temporary increase in current, which in conjunction with a fuse would stop the flow of electricity.

When we are dealing with an electrical 120-volt circuit, the same thing is true with our neutral white wire. It only appears to have zero volts because there is no resistance. If you become part of the circuit, the voltage will form across your body.

Now, in the case of a single-phase electrical subpanel, we know that 100% of the current from the hot-wires will travel on the neutral wires back to the main electrical cabinet. If we bond the ground wire to the neutral in the sub-panel, current will flow on both the neutral AND on the ground wire. Which means that if you do not keep the ground wires separate from the neutral wires, you will be allowing return currents to flow on the ground wires back to the main panel. This is not only bad for obvious safety reasons, but it will also cause problems with GFCI breakers and cause equipment interference issues. It is also of course a violation of the National Electrical Code (NEC). You are to have one and only one connection between the ground system and the neutral system, and that is at the first service disconnect. This is vital for the proper operation of over current protection devices (OCPD) such as fuses and circuit breakers.
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only the main panel from power feed may have the nuetral and ground tied together, ALL sub panels must maintain a seperate bus bar for ground and nuetral according to NEC. the GFCI will work properly as it is but its not to code. this will cause nuisance trips and as said get it done right and add the proper bus bar and the seperate wire. if its outdoors you need thxn that is stranded wire for wet areas
 

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