ratdoggy
Well-known member
Here's the quick synopsis. House with a detached garage, electric coming into it is a 2 wire cable (hot and neutral, no ground). How can I fix this short of digging up the cable and replacing it?
Add a gound?
- Thread starter ratdoggy
- Start date
cmandp
Well-known member
Removed so as to not add mis-information
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Alchymist
Well-known member
Sounds like 120v service only? Either way you need a ground from the main panel to the detached service. Just adding a ground rod won't fix it.
siegsuwa
Well-known member
[DELETED]
See wyliediesels' post.
See wyliediesels' post.
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wyliesdiesels
Well-known member
So 2-wire 120v?
Is there a breaker panel?
How is the wire fed to the garage? Conduit? What type of wire is it?
Ground rods have always been required on detached except for simple single circuits without a breaker panel BUT....
A ground rod is NOT the same thing as an equipment grounding conductor. A ground rod does NOT provide a low impedance fault current pathway. Ground rods are for grounding lightning.
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wyliesdiesels
Well-known member
This is completely wrong.
A ground rod or electrode is NOT the same thing as an equipment ground, which provides a low impedance fault current pathway. Fault current will NOT flow on ground rods back to the main panel to facilitate a breaker trip.
Tying the GEC from a rod to the ground terminals on outlets is DANGEROUS advice. DO NOT DO THAT.
And your word on code is wrong as well.
"The local building ground" im assuming you mean ground rod, and that has always been required. However, that NEVER provided the EGC between the sub and main. Prior to 2008, the neutral in a sub in a DETACHED BUILDING was allowed to be bonded and was used as the EGC. After 2008, a separate ground wire is required with an isokated neutral bar IN ADDITION to ground rods.
You really need to study up on the difference between grounding conductors and grounding electrodes.
There is an article in the Electrical FAQ thread you could read.
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cmandp
Well-known member
I removed my post so I did not confuse others.
Your post was most helpful wyliesdiesels as I indeed did not know the difference between a ground rod and equipment grounding conductor.
Your post was most helpful wyliesdiesels as I indeed did not know the difference between a ground rod and equipment grounding conductor.
siegsuwa
Well-known member
You're right, I suppose that I should have noted that it's not a recommended way to solve the problem, but he literally asked for the best way to do it without it being the best way.
I checked the Electrical FAQ and I think that the method that I recommended is consistent with the diagram for a 3-wire feed to a detached structure, which I noted was not code as of 2008. It's quite possible I didn't communicate clearly that was the strategy I was suggesting. However, to avoid confusion I've deleted my post to allow your post to be the authority in this thread.
cmandp
Well-known member
So a ground conductor must be run from the detached building to the main panel (where the neutral and ground bus are connected) where does the current go to trip the breaker, the transformer on the pole?
Just asking as it was wired without any type of ground going back to the panel. Damn there were live wires just cut and hanging outside of boxes. Also wires were just stuck into boxes with no clamps.
I guess I'll have to run new power to the garage with the correct stuff.
So I need a ground rod and a ground going back to the box in the house?
I guess I'll have to run new power to the garage with the correct stuff.
So I need a ground rod and a ground going back to the box in the house?
sberry
Banned
Yes, it goes to service neutral main. Old code allowed 3 wire feeds if there were not other interconnecting pathways. This all worked till someone came along and added a phone line or metal piping, water or gas then it made for alternative pathways for neutral currents as the N and the G needed to be bonded on 3 wire to have a pathway for faults back to the main.
If this is a 3 wire feed t needs a bond. As a side note here a while back I put a wire in and an old timer came back and hooked the panel up. He left the 4th wire dangle and used 3 while adding the bond screw as I recall. He had commented to someone,,, I am not sure what the 4th wire was for.
4 wire keeps all the operating currents insulated, neutrals are insulated and with everything hooked together keeps anything metal at the same potential. No difference between any 2 pieces in the event of a fault.
As was mentioned the ground rods are for lightening and some step potential between the equipment and the ground you are standing on.
sberry
Banned
Copied from another forum.
The panels in separate buildings are not really subpanels as far as code is concerned. They are the service equipment for the structure. You can have a subpanel from the service equipment in each building if you want. Between buildings, section 250.32 applies and if there are metal interconnections between buildings such as water piping, or air lines, or any metal interconnection at all, then you must install an equipment ground wire so if you have a 120/240 system, you would have four wires. The neutral would be separated in each building and a grounding bar would be installed, just like a subpanel. Then the code requires a grounding electrode conductor (GEC) to a grounding electrode (usually a ground rod). The GEC will be connected to the equipment ground bar at each building. This is not to clear overcurrent devices, this is for two reasons. One is lightning, the more important one is to put the equipment ground at the same relative potential as the earth. This is for step potential or touch potential voltages so that what you touch in the building is at the same potential as what you are standing on. Now the tricky part. If you do not have any interconnecting metal between buildings, the code allows you to install three conductors between buildings. When you do this you bond the neutral and ground the neutral just like a new service. Some inspectors think that every panel in a separate building must be treated as a subpanel, but this is not true. In past codes (1996 and older) these rule were in section 250-24 and Exception 2 addressed the grounding bus.
Last changed: June 17, 2002
The panels in separate buildings are not really subpanels as far as code is concerned. They are the service equipment for the structure. You can have a subpanel from the service equipment in each building if you want. Between buildings, section 250.32 applies and if there are metal interconnections between buildings such as water piping, or air lines, or any metal interconnection at all, then you must install an equipment ground wire so if you have a 120/240 system, you would have four wires. The neutral would be separated in each building and a grounding bar would be installed, just like a subpanel. Then the code requires a grounding electrode conductor (GEC) to a grounding electrode (usually a ground rod). The GEC will be connected to the equipment ground bar at each building. This is not to clear overcurrent devices, this is for two reasons. One is lightning, the more important one is to put the equipment ground at the same relative potential as the earth. This is for step potential or touch potential voltages so that what you touch in the building is at the same potential as what you are standing on. Now the tricky part. If you do not have any interconnecting metal between buildings, the code allows you to install three conductors between buildings. When you do this you bond the neutral and ground the neutral just like a new service. Some inspectors think that every panel in a separate building must be treated as a subpanel, but this is not true. In past codes (1996 and older) these rule were in section 250-24 and Exception 2 addressed the grounding bus.
Last changed: June 17, 2002
wyliesdiesels
Well-known member
The neutral to ground bond in the main service panel allows fault current to be a line to neutral fault. This bond is critical for the fault current pathway. The breaker sees this fault and trips. Without the neutral to ground bond, breakers wouldnt be able to trip.
Depending on the size of the service and the available fault current from the transformer, this fault can be thousands of amps for mere milliseconds.
I have had service call once where water and gas lines in a rental were energized. It turned out that no one had EVER bonded the water line coming into the house and it came in right under the main service panel. One of the circuits had a bare hot wire that was contacting the ground wire in a Romex cable(i never did find it) and this in turn energized the ground terminal on the outlet feeding the gas range.
I dont know how this place passed inspection when it was missing the water line bond.
Some bozo hired by the landlord, previous to me, drove in a ground rod at the main service panel and one at the subpanel in the garage to try to "fix" the issue. After hooking it up, he still couldnt figure out why the water line was energized and why tenants were being shocked while they stood outside on concrete touching the hose bib.
If you do a new feeder to the garage WITH A SUBPANEL, then yes you need both.
If instead you do a single 20a circuit to the garage WITHOUT a subpanel, then you can forgo the ground rods.
Most hand tools these days do not need a grounded outlet.
Now that weve establish the theory, what do you plan on doing in the garage? What loads and equipment will you have?
Excellent additional info and your english is near perfect this time!
Great job!
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wyliesdiesels
Well-known member
Yeah thats a bit dated as 4-wire is required for detached on new installs post 2008 EVEN if there are no other metallic pathways.
ez-duzit
Well-known member
If the 2-wire service is in a conduit, disconnect it and use that for pulling a messenger line through. Then use the messenger line to pull the original 2 wires plus a ground through.
wyliesdiesels
Well-known member
Depends on the wire method use for the 2-wire.
If UF or god forbid NM, then no go as all conductors must be in same jacket.
IMPO if one is gonna go to all that trouble to pull the old out, I would just pull in a larger feeder. Unless of course the conduit is too small.
ez-duzit
Well-known member
The ground does not need to be in the same jacket.
wyliesdiesels
Well-known member
Code requires all conductors of the circuit to be in the same raceway or jacket.
The exception is retrofitting 2-wire outlets to 3-wire outlets on a 2-wire system.
ez-duzit
Well-known member
The ground is not one of the conductors in any circuit; it is a separate ground, and is in the same raceway/conduit.
Alchymist
Well-known member
Conductor: a substance, body, or device that readily conducts heat, electricity, sound, etc.:
The ground is a conductor, and in certain instances it will conduct current.
ez-duzit
Well-known member
The ground is made of conductive material but is not one of the conductors in the circuit.
Alchymist
Well-known member
Wrong,it doesn't conduct during normal operation, it can conduct in a fault situation. Without it, certain fault conditions will not cause a breaker trip. Wire up a circuit without it, and the inspector will tell you you are missing a conductor. That's why detached sup panels are wired with 4 conductor cable.
teamextreme
Well-known member
It is called an equipment grounding CONDUCTOR.
ez-duzit
Well-known member
So is the band leader.
wyliesdiesels
Well-known member
Give me a break. 
ez-duzit
Well-known member
Try not to get too hung up on these names. 
wyliesdiesels
Well-known member
Try not to get too hung up on these names.
How about you go read 300.3(B)(1)-(4)
ez-duzit
Well-known member
Is that where it says that current carrying conductors should be in the same jacket?
wyliesdiesels
Well-known member
It says all conductors including any egcs
I dont know why youre wasting so much time on this.
Alchymist
Well-known member
I think one thing that confuses many people (including ez-duzit), are the abbreviations "EGC" & "GEC", and the difference between the two. The old saying "Ground is ground the world around" doesn't apply here.
wyliesdiesels
Well-known member
Just the reason for post #4 in the electrical FAQ sticky!!
https://www.garagejournal.com/forum/showpost.php?p=6410418&postcount=4
arkieguide
Well-known member
- Joined
- Aug 10, 2017
- Messages
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ground and grounding, bonding, & lightning ground,
can get confusing to the layman. You need 3 wires hot, neutral, & ground, ground and neutral are separate all the way back to the main panel where they connect and go the ground rod and service ground. With 3 wires you still need a ground rod at the end of your run.Ground wire goes to it, the neutral and grd. do not connect at this point. You can add a ground wire separate from the feed cable if you want ?
can get confusing to the layman. You need 3 wires hot, neutral, & ground, ground and neutral are separate all the way back to the main panel where they connect and go the ground rod and service ground. With 3 wires you still need a ground rod at the end of your run.Ground wire goes to it, the neutral and grd. do not connect at this point. You can add a ground wire separate from the feed cable if you want ?
Alchymist
Well-known member
For anything coming off the main panel you need a neutral, an EGC, and one or two hot legs - 120 or 240 volts. Needing a ground rod depends - detached sub panel, yes. Sub panel in same building, no. Neutral and EGC are connected at only one point in the system, usually the main panel, never in a sub panel. Why are people making this so hard?
wyliesdiesels
Well-known member
Nothing like beating a dead horse?
And i covered this topic in the Electrical FAQ sticky already.
ez-duzit
Well-known member
Because of misinformation?
You don't need neutral for a 220-volt circuit, just 2 out of phase 110-volt legs and ground.
Alchymist
Well-known member
Yeah, read it in context of the post quoted. True, you don't need a neutral for a straight 240 volt circuit, but guess what - many of us will pull one anyway - plans change, and sometimes that neutral comes in handy. And, by the way, its 120 and 240 volts.
