Grounding neutral at outlet box??

[milemaker13]

Another question pertaining to all these old homes with old wiring...

In an old home where the outlets have no ground connection but are other wise wired correctly....

Can I simply use a jumper from the neutral terminal to the grouding screw on my outlet?

I recently correctly outlets in my house by running a ground wire from grounded conduit strap to my ungrounded outlet box. I have a small job later today involving ungrounded outlets..

Electrically, this seems OK. Ultimatly, both the neutral and the ground conductor orignate from the same breaker box (neutral bonded in breaker box).

However, it does seem too easy to be legal. What are the pro's and con's of doing this?

 

[iwire]

Electrically, this seems OK. Ultimatly, both the neutral and the ground conductor orignate from the same breaker box (neutral bonded in breaker box).

However, it does seem too easy to be legal. What are the pro's and con's of doing this?

Beyond being a direct code violation it is a dangerous thing to do. You would be better off without any grounding connection to the outlet and installing GFCIs. If you do what you suggest a broken wire can lead to appliances with energized metal parts.


But you are in Chicago, it should be conduit and conduit is a grounding conductor.

 

[infinity]

What is the wiring method metallic conduit?

 

[milemaker13]

Yes, mostly conduit around here. But this job is out in the country where romex is still allowed. Not sure just how old this place is. A co-worker bought a house to serve as a dorm for his two kids and their two friends while at collage in dekalb.

Ok, reading a few things online... I understand I should not do this, and I think I even understand why Possibility of sending neutral current thru metal parts... and creating issues with 'phantom voltages'?

But, it sounds like it would in fact fool an inspectors test meter??

You say better to just leave them ungrounded? Really?

What about running a single grounding jumper from solidly grounded metal box to the ungrounded outlet box? Not the neutral; steel box connected to steel box.

 

[kwired]

That method will raise the voltage potential of everything connected to the EGC terminal of the receptacle to the same potential as any voltage drop on the neutral conductor. If you do have metal raceways it will put them in parallel with the neutral conductor and the raceways will be carrying a portion of the neutral current.

There are reasons why we bond the grounded conductor at the service and keep it separated from the EGC after that point.

What I described is normal operation issues, abnormal operation issues can be even bigger problems.

 

[iwire]

You say better to just leave them ungrounded? Really?

Yes, really is safer than using the neutral to ground a branch circuit.

As far as what will fool and inspector, we don't help with that on this forum.

 

[kwired]

What about running a single grounding jumper from solidly grounded metal box to the ungrounded outlet box? Not the neutral; steel box connected to steel box.

Code aside - that is better then utilizing the neutral conductor for equipment grounding purposes, and at one time was somewhat code acceptable, but not anymore. Recent code editions require the EGC to run with the circuit conductors - this is in part to help decrease impedance in the circuit during a ground fault event, less impedance means more fault current can flow and will result in faster response from overcurrent protective devices.

 

[qcroanoke]

Yes, mostly conduit around here. But this job is out in the country where romex is still allowed. Not sure just how old this place is. A co-worker bought a house to serve as a dorm for his two kids and their two friends while at collage in dekalb.

Ok, reading a few things online... I understand I should not do this, and I think I even understand why Possibility of sending neutral current thru metal parts... and creating issues with 'phantom voltages'?

But, it sounds like it would in fact fool an inspectors test meter??

You say better to just leave them ungrounded? Really?

What about running a single grounding jumper from solidly grounded metal box to the ungrounded outlet box? Not the neutral; steel box connected to steel box.

You are allowed by code to use 3 wire receptacles that are ungrounded as long as there is a GFI receptacle or breaker feeding them. Otherwise you should be putting back 2 wire receptacles.

 

[milemaker13]

As far as what will fool and inspector, we don't help with that on this forum.

Haha, no, not trying to fool an inspector. Let me re-phrase the question: So, using the neutral wire as a ground would give a false "correctly wired" reading on a plug in style meter?

I'm only trying to under stand it all better. Certainly don't want to create a hazard where none existed before!

 

[milemaker13]

There are reasons why we bond the grounded conductor at the service and keep it separated from the EGC after that point.

.

Its one of those things I've always wondered about, never getting a clear answer...

I think this sums it up well. Makes sense... sort of,:blink: :lol:

 

[GoldDigger]

Haha, no, not trying to fool an inspector. Let me re-phrase the question: So, using the neutral wire as a ground would give a false "correctly wired" reading on a plug in style meter?

I'm only trying to under stand it all better. Certainly don't want to create a hazard where none existed before!

Yes, in that circumstance a simple indicator type tester would show the same pattern of lights as it would for a correctly wired socket.
A more sophisticated meter that reads out VD and other information would detect the "fake" ground because the N to G resistance would be too low to be believable.
(However that same meter would typically fail a convenience receptacle right next to the main panel.)

Tapatalk!

 

[Jon456]

Haha, no, not trying to fool an inspector. Let me re-phrase the question: So, using the neutral wire as a ground would give a false "correctly wired" reading on a plug in style meter?

What you described earlier (connecting the receptacle's ground terminal to its neutral terminal) is commonly referred to as a "bootleg ground" and it is dangerous. What's even more dangerous is a "reverse bootleg ground" where the receptacle's ground terminal is connected to its neutral terminal, but then the polarity of the terminals is reversed: the receptacle's hot terminal is connected to the building's neutral wire and its neutral terminal is connected to the building's hot wire. This will energize both the neutral and the ground (as well as the receptacle's frame and the outlet box if it's metal). But when you plug a 3-light tester into a receptacle with a "bootleg ground" -- even one with a "reverse bootleg ground" -- the tester will show that it is wired correctly!

 

[1793]

What you...dangerous. What's even more dangerous is a "reverse bootleg ground" where the receptacle's ground terminal is connected to its neutral terminal, but then the polarity of the terminals is reversed: the receptacle's hot terminal ....the tester will show that it is wired correctly!

If memory serves me correctly, I had this same situation at a customers Apt. This set up was putting 120V on their TV coax cable when they pluged in their 3 pronged X-Box and as a result they blew up 2 Flat panel TV sets. I found the problem and corrected it but it took quite a bit of time to sort it out.

 

[don_resqcapt19]

...

But, it sounds like it would in fact fool an inspectors test meter??

....

There is at least one tester on the market that was specifically designed to catch that violation as well as other problems. A number of inspectors around here use that tester.

 

[Jon456]

There is at least one tester on the market that was specifically designed to catch that violation as well as other problems. A number of inspectors around here use that tester.

I don't know if this is the tester you're referring to, but the Ideal SureTest Circuit Analyzer will identify bootlegged grounds:

 

[milemaker13]

This customer has several ungrounded circuits thru out the house as well as a few other issues.

"You are allowed by code to use 3 wire receptacles that are ungrounded as long as there is a GFI receptacle or breaker feeding them. Otherwise you should be putting back 2 wire receptacles."


Can you tell me where to find this in the code book?

If this is correct, I plan to install gfci breakers and outlets. Does a light fixture affect a gfci's operation? Ex: Using a gfci breaker where a light is fed from that outlet/circuit?

 

[qcroanoke]

Can you tell me where to find this in the code book?

If this is correct, I plan to install gfci breakers and outlets. Does a light fixture affect a gfci's operation? Ex: Using a gfci breaker where a light is fed from that outlet/circuit?

2008 NEC
406.D-(3)a, b, c.

 

[kwired]

Its one of those things I've always wondered about, never getting a clear answer...

I think this sums it up well. Makes sense... sort of,:blink: :lol:

If we don't keep the EGC isolated from the grounded conductor beyond the service, we begin to make a complex network of objects that are bonded to each other that are also bonded to the current carrying grounded conductor, giving us multiple paths for that current to follow.

It is bad enough that we have accepted a system on the supply side of service equipment that does operate this way and it does create "stray voltage" issues at times. If a particular path is carrying current and becomes disrupted you can end up with voltage potential between objects that otherwise were not intended to be energized. Add to that voltage drop issues. When current flows through a conductor (any conductor including the metal frames of non electrical items) there is some resistance in that conductor that creates a voltage drop. If you touch that object and a "true earth potential" object you will be subject to any voltage drop that is present on that "conductor". This is a very real thing that happens all the time with the utility side of the service equipment, most of the time that voltage is pretty minimal, but there are times when things go wrong and it creates problems. This situation is part of why we need to provide all the equipotential bonding we do in certain areas like swimming pools or livestock buildings, as we are not only trying to equalize potential when something local happens, we are also trying to equalize potential during normal operation as well as the voltage drop on the POCO's distribution network is imposed on the service neutral - because it is bonded to their distribution side there is nothing there to tell those electrons carrying supply side current they can't go this way, they flow whatever path the resistance dictates.

 

[growler]

I plan to install gfci breakers and outlets. Does a light fixture affect a gfci's operation? Ex: Using a gfci breaker where a light is fed from that outlet/circuit?

I have not had any problems protecting light fixtures with GFCI.


The only thing I can think of where you may have a problem is some of the older exhaust fan motors ( bath exhaust ). Some will only run for a short time and then trip the GFCI.

Make sure the customer knows how to reset a GFCI breaker. He may have old lamp cords or other defective appliances that will trip the GFCI.Good thing to find out anyway.

 

[al hildenbrand]

This customer has several ungrounded circuits thru out the house as well as a few other issues.

Speaking to your use of "issues" --

An "ungrounded circuit" is NOT an issue, by itself. Assuming that the ungrounded circuit was installed to the requirements of the Code in effect for that area at the time of original installation of the wiring, then it is good.

There are good discussions here, in the archives, about how ungrounded circuits in a wood frame house, where the construction is non-conductive, are arguably safer that a grounded circuit.

In an old house, one finds original two wire ungrounded receptacles mostly in the bedrooms and living rooms. Think about the modern items that one most commonly plugs in to receptacles that are placed in bedrooms and living rooms. Items like lamps, TVs, clocks, sound systems, chargers and small electronics power supplies. . . virtually all having two prong, non grounding plugs. 90 to 95% of what is commonly used has no need for a grounding type receptacle.

Something like a window AC or an electric heater already needs a new circuit, most of the time, so the new receptacle for that, by today's Code, will be grounding type. . . so it's covered.

And, now, add the requirements of 2011 National Electrical Code 406.4(D)(4), and you run into the buzz saw of adding AFCI to the existing receptacle, along with GFCI and Tamper resistance.