ground rod for garage 2-wire

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rob-1

Member
Location
California
Can a ground rod be used as follows for this situation?
House has mostly 2-wire (no grnd) wiring except for bathroom ckts. Same in garage.
Thinking a ground rod outside of garage wall wired to washer & dryer duplex 120v ckts for temp grounding until new 12/2 nmb cable (w/ground)is run from panel to garage. No other grnds either from panel, existing 2 wire (of course), or anywhere else are feeding the attached/stucco/with aluminum siding wood framed residential garage.
Rob-1
 

bphgravity

Senior Member
Location
Florida
Re: ground rod for garage 2-wire

There has to be a grounded conductor at the service. If you drive a ground rod it needs to be connected to this back at the service. If you don't, in the event of a short, the fault will flow to earth and never clear. Earth cannot be the only means of equipment grounding.
 

txsparky

Member
Location
Conroe, Texas
Re: ground rod for garage 2-wire

The ground rod would serve no purpose unless it is bonded to the ground rod and neutral at the main panel.Your safest installation would be a new 12-2 w/grd 20 amp circuit.The other option would be a gfci receptacle.
 

hurk27

Senior Member
Re: ground rod for garage 2-wire

GFCI's dont like washer's the fill valve coil will spike them and cause nuesent tripping. but you did say that there is a washer in this garage?
If the water pipe supplying the garage from the house is a metel pipe then you have it made :D as you can bond it to your main panel neutral(which it should be already) and then use it in the garage to bond the receptacle's grounds as allowed in:

406.3 (1) Grounding-Type Receptacles. Where a grounding means exists in the receptacle enclosure or a grounding conductor is installed in accordance with 250.130(C) , grounding-type receptacles shall be used and shall be connected to the grounding conductor in accordance with 406.3(C) or 250.130(C).

250.130(C) Nongrounding Receptacle Replacement or Branch Circuit Extensions. The equipment grounding conductor of a grounding-type receptacle or a branch-circuit extension shall be permitted to be connected to any of the following:
(1) Any accessible point on the grounding electrode system as described in 250.50
 

tom baker

First Chief Moderator
Staff member
Re: ground rod for garage 2-wire

Rob- A ground rod is to stablize the voltage to ground and prevent overvoltage from lihgtning or transients.
You are better off with 2 wire non gounded circuits and GFCI protection than grounded circuits.
Even though a GFCI can be used to replace a non grounded recptacle, it is a compormise, some devices require a ground to work properly, such as a TVSS.
 

rob-1

Member
Location
California
Re: ground rod for garage 2-wire

Tom and Hurk27,
hurk27 makes a point about using GFI's (yes there is a washer) tripping by the washer's fill valve coil. Also, his idea of grounding the garage duplex outlet to the water pipe sounds like a plan.

tom said just install GFI's, but what about a path to ground if needed if i just follow tom's idea (use the existing 2wire w/o a ground).

Yes, the water pipe at the main is bonded to the main's ground rod which feeds the panel ground bus which is bonded to the floating neutral bus. So if i just run a ground jumper from the garage water pipe to the duplex 120v outlet then according to hurk27 and the nec i should be fine, right? One additional item, is there a minimum depth the water pipe need to be underground. I know the water pipes run continuously from the meter to the house and within a few feet of the main (where it's bonded to the main's ground rod) but the water pipes aren't buried very deep. Maybe from 1ft min to two 2max depth (as they leave the house and head off toward the street side main).
thnx
 

rob-1

Member
Location
California
Re: ground rod for garage 2-wire

bphgravity,
BTW, are u saying that if i did (probably won't any longer) run a g-rod at the garage area I'd have to bond it the the main's g-rod at the panel because that where it's bonded to the neutral? if so, i'd rather try hurk27's idea. but i see your point about a fault not clearing if it was a solitary g-rod at the garage independent from the main's neutral/g-bus/g-rod/ bonding.
thnx.

"If you don't, in the event of a short, the fault will flow to earth and never clear. Earth cannot be the only means of equipment grounding."
 

hurk27

Senior Member
Re: ground rod for garage 2-wire

Rob there is no requirment on how deep just for the continuity of the pipe as in any electrical circuit it's the continuty that allows the current to flow and open the ocp device. this is not the best way but it is an allowed way for older non-grounded wiring. and is allowed for fixture's too. Keep the thought about updating the electric though, as it would provide a safer enviroment for your familiy to live in.

P.S. GFCI's will work without a ground wire attached to it. the way a GFCI works it does not need a ground. now tvss on the other hand cannot protect against a ground surge comming in on the cable wire or phone wire without a ground wire to bleed off the surge on. but will still protect for surges between the hot and neutral (the most damaging type)

[ March 14, 2003, 12:52 AM: Message edited by: hurk27 ]
 

stamcon

Senior Member
Re: ground rod for garage 2-wire

Hurk27, just a question regarding 250-50(99NEC). "Interior metal water piping located more than 5ft(1.52m) from the point of entrance to the building shall not be used as a part of the grounding electrode system or as a conductor to interconnect electrodes that are part of the grounding electrode system."

If the equipment ground connection to the water pipe for this receptacle, is more than 5' from where the water pipe enters the structure, isn't that a violation?

Doesn't the "grounding electrode system" stop at the 5' distance on the water pipe?
 

rob-1

Member
Location
California
Re: ground rod for garage 2-wire

hurk27,
thnks and doesn't stamcon's comment refer to 5 feet from the main panel (or am i reading it wrong?) ie, water/g-rod bond panel not > 5' from the main panel? i don't have the nec (1999) so i can't ck on the stamcoms ref. don't want to seem like i couldn't at least read 250-50(1999) myself b4 asking.
Stamcon, not that i'm unappreciative of your question/comment but both u an i are asking, and hurk27 has some answers.
 

rob-1

Member
Location
California
Re: ground rod for garage 2-wire

clarification:

"ie, water/g-rod bond panel not > 5' from the main panel?"
SHOULD READ:
"ie, water/g-rod bond not > 5' from the main panel?
 

hurk27

Senior Member
Re: ground rod for garage 2-wire

H'MMMMM is there not a differance between an equipment grounding conductor and a electrode grounding conductor?
250-50 Is for when you use a water pipe for an grounding electrode (as he has in the house by the panel) not for when it is used for equipment grounding. and this requirment farther says that meter or filters have to be bonded around if there in the path to the earth. and it allows for an egc to be used for the grounding of replacement receptacle's when there is no ground wire run with the circuit conductors.

Burying the pipe any deeper would not have any affect on the fault clearing ability of the pipe as earth is not for this perpose (to high of resistance). but at higher voltages like when lightning strikes it has a lot better ability to draw this voltage to ground and this is why the nec requires the pipe to have at least 10' in the ground and the egc connection within 5' of where it enter's the building. as a egc is only for the protection from voltages of a higher source! and that is the only thing it is for.
 

stamcon

Senior Member
Re: ground rod for garage 2-wire

A metallic water pipe with at least 10' in the earth can(shall) be used as a "grounding electrode". The point of connection of the "grounding electrode conductor" to the water pipe must be within 5' of where the water pipe enters the structure.

Yes, there is a difference between the "grounding electrode conductor" and an "equipment grounding conductor".

250-50 says the "equipment grounding conductor" can be attached anywhere to the "grounding electrode system".

My question is, is the metallic water pipe still part of the "grounding electrode system", more than 5' from where it enters the structure?

I've had an inspector not allow using interior(more than 5')metallic water pipe to connect an "equipment ground conductor" to.
 

hurk27

Senior Member
Re: ground rod for garage 2-wire

Here's the 2002's nec CODE "ON GROUNDING ELECTRODES" not equipment grounding


250.52 Grounding Electrodes.
(A) Electrodes Permitted for Grounding.
(1) Metal Underground Water Pipe. A metal underground water pipe in direct contact with the earth for 3.0 m (10 ft) or more (including any metal well casing effectively bonded to the pipe) and electrically continuous (or made electrically continuous by bonding around insulating joints or insulating pipe) to the points of connection of the grounding electrode conductor and the bonding conductors. Interior metal water piping located more than 1.52 m (5 ft) from the point of entrance to the building shall not be used as a part of the grounding electrode system or as a conductor to interconnect electrodes that are part of the grounding electrode system.

Now we look at what the nec allows for his condition:


(C) Nongrounding Receptacle Replacement or Branch Circuit Extensions. The equipment grounding conductor of a grounding-type receptacle or a branch-circuit extension shall be permitted to be connected to any of the following:
(1) Any accessible point on the grounding electrode system as described in 250.50
(2) Any accessible point on the grounding electrode conductor
(3) The equipment grounding terminal bar within the enclosure where the branch circuit for the receptacle or branch circuit originates
(4) For grounded systems, the grounded service conductor within the service equipment enclosure
(5) For ungrounded systems, the grounding terminal bar within the service equipment enclosure

And as it say's we are alowed to connect it to the grounding electrode if it was properly connected to the panel as this would provide the required fault path back to the return (neutral) not to earth.

The requirment you see in 250.50 is a requirment for the gec. not for us bonding to it for a egc

As it referred us to:
250.50 Grounding Electrode System.
If available on the premises at each building or structure served , each item in 250.52(A)(1) through (A)(6) shall be bonded together to form the grounding electrode system . Where none of these electrodes are available, one or more of the electrodes specified in 250.52(A)(4) through (A)(7) shall be installed and used.

250.52 Grounding Electrodes.
(A) Electrodes Permitted for Grounding.
(1) Metal Underground Water Pipe. A metal underground water pipe in direct contact with the earth for 3.0 m (10 ft) or more (including any metal well casing effectively bonded to the pipe) and electrically continuous (or made electrically continuous by bonding around insulating joints or insulating pipe) to the points of connection of the grounding electrode conductor and the bonding conductors. Interior metal water piping located more than 1.52 m (5 ft) from the point of entrance to the building shall not be used as a part of the grounding electrode system or as a conductor to interconnect electrodes that are part of the grounding electrode system.
 

stamcon

Senior Member
Re: ground rod for garage 2-wire

"250.52 Grounding Electrodes.
(A) Electrodes Permitted for Grounding.
(1) Metal Underground Water Pipe. A metal underground water pipe in direct contact with the earth for 3.0 m (10 ft) or more (including any metal well casing effectively bonded to the pipe) and electrically continuous (or made electrically continuous by bonding around insulating joints or insulating pipe) to the points of connection of the grounding electrode conductor and the bonding conductors. Interior metal water piping located more than 1.52 m (5 ft) from the point of entrance to the building shall not be used as a part of the grounding electrode system or as a conductor to interconnect electrodes that are part of the grounding electrode system."

So the last sentence says the interior water pipe is not part of the "grounding electrode system". Therefore, a person can't attach an "equipment grounding conductor" to the interior pipe. This would be a violation. Correct?
 

hurk27

Senior Member
Re: ground rod for garage 2-wire

Boy you type fast :D LOL :D

From what I read is we must follow the path of current for which the circuit applys to.
now a equipment grounding conductor is for the removal of a fault current that might be imposed on it from a ground-fault condition. this path does not go to earth!it goes to the point of return of the source of the current. the fact that the ge is of no effect as the removal of it (putting a plastic peice of water pipe in between the connection and the street) would not affect the fault clearing ability of the egc from the water pipe back to the panel if the egc was connected to the water pipe in the garage as long as there is a connection between the water pipe and the neutral the breaker will trip and open the fault. the gec to the water pipe is only there to protect the panel from higher voltages that might come into contact with the system or from the effects of a lightning strike. these are two very differant perpose of two differant wire that just happen to be useing the same water pipe and path back to the panel. and have to be analized in differant ways as the gec cannot clear a fault and a egc cannot clear a lightning strike. this inspector is mixing the two together.
 

hurk27

Senior Member
Re: ground rod for garage 2-wire

Ok here's another way that someone could look at it the egc is connected to a copper water pipe the egc is bare and so is the water pipe they both can carry the required fault current and the pipe probely excides this requirment. now this pipe runs past the point of the gec connection (within 5')and is effectivly connected to the ge as it is part of the same pipe. if the egc is effectivly connected to the water pipe via a listed clamp then I cant see where there is a problem.

Besides if you could not do this then the code allowing this would be worthless as if you could get back to the point of where the gec makes its connection to the water line you probly could just run to the panel anyway so why would they need to put this in the nec if it wouldn't meen anything?

The other thing to think about is if this house is a ungrounded system it probley didnt have to follow the 2002 nec when it was manufactured which means that the gec is there just to bond the water pipes and does not have the 5' rule even in the nec of it's time so how could the nec require somthing that was not code back then? would this mean we would have to run a new gec? the nec is not retroactive as it says

[ March 14, 2003, 02:32 AM: Message edited by: hurk27 ]
 

stamcon

Senior Member
Re: ground rod for garage 2-wire

When 250-50 says that only the first 5' of the water pipe can be part of the "GEC system" and 250-52(250-130(c)(1)99NEC) says that the "EGC" can connect to any part of the "GEC system", interior water pipe is not part of the "GEC" system", according to 250-50 and therfore no "EGC" connection.

I know as long as the pipe is electrically continous from the garage to the house and the water pipe in the house is being used as a "GE", that fault clearing from the garage wouldn't be a problem, but I don't think it's legal by current code. Good night for now. steve

[ March 14, 2003, 02:49 AM: Message edited by: stamcon ]
 

electricmanscott

Senior Member
Location
Boston, MA
Re: ground rod for garage 2-wire

You absolutely can not use interior metal piping to ground an undgrounded system in a residence. You must run the ground back to the panel or the grounding electrode or grounding electrode conductor. The NEC is very clear on this.
 
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