Pre-existing underground Wire gong to detached garage

Hello,

I have a detached garage relatively far from the main circuit breaker the the point of entrance of power to the house. The wires are buried, it seems to be alumminum wires, and I would guess the gauge would something like 4 or 5 (nothing written on cable sheathing, and marks).

I understand that there is no need to a ground wire travelling from the main to the subpanel due to the fact that the neutral line is already grounded; but in these situation I would imagine that there should be a ground rod next to the garage building itself, and I was wondering whether or not this would be required? (currently there is no ground rod visible and no ground wire per se going to the subpanel in the garage).

I am not sure whether or not the whole the underground cable is travelling inside conduit (I guess it depends on the depth of the burial, etc), but at the end points the wires do exit the ground from a pvc conduit. At the garage there is a pvc conduit exit the ground and going all the way to a hole in the concrete wall (so the wires are not exposed), but near the house the point that the wires exit the ground is not protected by conduit (no sure if that is ok by code) as shown below (please ignore all mess of wires – they have been removed already – and only look into the pvc conduit protruding from the ground):


In the interior of the garage I am installing a new subpanel, as shown below:

Previous installs are grandfathered and did not require a ground wire. Current installs do require a ground wire. The old three wire feed required a ground rod at the garage.

Since this appears to be a new install a ground wire is required. At the very least the conductors I see coming into the bottom new panel must be in conduit. Individual conductors like those pictured must be in conduit all the way.

Looks like you will have to install a bar for ground in the panel box. On a sub-panel, the grown bar and neutral bar must be separate

JoeD said:

Previous installs are grandfathered and did not require a ground wire. Current installs do require a ground wire. The old three wire feed required a ground rod at the garage.

Since this appears to be a new install a ground wire is required. At the very least the conductors I see coming into the bottom new panel must be in conduit. Individual conductors like those pictured must be in conduit all the way.

Click to expand...

So, I would need a separate ground rod for the garage (I assume one ground rod will suffice, not needing two). The copper #6 bare ground wire would likely take a different path to get inside the garage and it would not need to be in a conduit?

Yeah, it is a new circuit breaker panel and there will be new wires (and since it is a garage and more prone to have rodent) it will all be in a conduit (bx or emt).

I hope there is no need of a conduit inside the concrete walls because the wire enters the wall inside a conduit from the ground and then inside the walls it travels up to the spot whereon the subpanel is. Would a small flexible conduit from the point the cable exit the wall to the subpanel suffice?

thanks!

kok328 said:

Looks like you will have to install a bar for ground in the panel box. On a sub-panel, the grown bar and neutral bar must be separate

Click to expand...

Yep, I know that. It still is a working in progress. thks!

kok328 said:

Looks like you will have to install a bar for ground in the panel box. On a sub-panel, the grown bar and neutral bar must be separate

Click to expand...

This is a repair and replacement of the wiring in the detached structure. The Feeder is grandfathered so a separate Equipment Grounding Conductor (EGC) in the feeder is not required.

What is required is a Grounding Electrode System which does meet all of the requirements for an service equipment installation. That means that you will have to measure; perhaps under observation by the AHJs inspector; the impedance of the first ground rod to assure that it is less than Twenty Five Ohms; OR you can just drive a second ground rod and call it done.

Since the existing Feeder installation must be wired as if it were a utility supplied service there will be no immediate need for a separate EGC Buss Bar in the Garage's panel. That said it would do no harm to install one to make the installation ready for any future change in it's supply conductors. One thing to be aware of if you do install a separate EGC buss bar is that as long as the feeder is only three conductors both the EGC buss bar and the Neutral buss bar must be bonded to the Neutral conductor of the feeder at the Building Disconnecting Means; in your case the garage's panel.

The National Institute of Standards and Technology (NIST) has done extensive research on electrical grounding and has published a best practices guide for installation of Grounding Electrode Systems at buildings that do not have any of the more effective Grounding Electrodes present at the structure already. Were there is no Underground Metal Water Piping, Ground Ring, or Concrete Encased Electrode; best practice would be to install the two Driven Rods at least the sum of their own lengths apart and to drive them through the bottom of a trench that is at least Two and one half feet deep. You connect the rods to each other and to the Building Disconnecting Means by installing a bare copper conductor, #2 AWG or larger, in the bottom of the trench so that it's entire length, until it reaches the building, will be buried a full thirty inches deep. If you check the code language you will find that that matches the requirements for a Ground Ring as to depth of bury, conductor size, and length. The only thing it does not do that a Ground Ring would is to circle the entire structure.

Since the garage's panel cabinet will function as the Building Disconnecting Means Enclosure it must have a main breaker/s; totaling no more than six breakers, or have no more space then would be enough for Six double pole breakers. If single pole breakers are installed they must be handle tied into pairs so that it would never take more than six throws of the hand to disconnect all power from the building. Best practice would be to have a single main breaker as the Building Disconnecting Means but the code only limits the number of main breakers to Six.

Those are the high points. Do let us know if you have more questions.

Conduit is require the full length of those wires, even inside the concrete walls.

Yeah Joe is right, I just noticed the individual feeder wires coming out of the concrete wall and going into the bottom of the panel. Those wires, as is, are not considered protected and need to be, even through the wall. You may be able to get an LB and reducing washers so you don't have to alter the setup, but that looks pretty tight.

Non armored sealtite might work there too, but it still looks tight. Good luck.

hornetd said:

This is a repair and replacement of the wiring in the detached structure. The Feeder is grandfathered so a separate Equipment Grounding Conductor (EGC) in the feeder is not required.

What is required is a Grounding Electrode System which does meet all of the requirements for an service equipment installation. That means that you will have to measure; perhaps under observation by the AHJs inspector; the impedance of the first ground rod to assure that it is less than Twenty Five Ohms; OR you can just drive a second ground rod and call it done.

Since the existing Feeder installation must be wired as if it were a utility supplied service there will be no immediate need for a separate EGC Buss Bar in the Garage's panel. That said it would do no harm to install one to make the installation ready for any future change in it's supply conductors. One thing to be aware of if you do install a separate EGC buss bar is that as long as the feeder is only three conductors both the EGC buss bar and the Neutral buss bar must be bonded to the Neutral conductor of the feeder at the Building Disconnecting Means; in your case the garage's panel.

The National Institute of Standards and Technology (NIST) has done extensive research on electrical grounding and has published a best practices guide for installation of Grounding Electrode Systems at buildings that do not have any of the more effective Grounding Electrodes present at the structure already. Were there is no Underground Metal Water Piping, Ground Ring, or Concrete Encased Electrode; best practice would be to install the two Driven Rods at least the sum of their own lengths apart and to drive them through the bottom of a trench that is at least Two and one half feet deep. You connect the rods to each other and to the Building Disconnecting Means by installing a bare copper conductor, #2 AWG or larger, in the bottom of the trench so that it's entire length, until it reaches the building, will be buried a full thirty inches deep. If you check the code language you will find that that matches the requirements for a Ground Ring as to depth of bury, conductor size, and length. The only thing it does not do that a Ground Ring would is to circle the entire structure.

Since the garage's panel cabinet will function as the Building Disconnecting Means Enclosure it must have a main breaker/s; totaling no more than six breakers, or have no more space then would be enough for Six double pole breakers. If single pole breakers are installed they must be handle tied into pairs so that it would never take more than six throws of the hand to disconnect all power from the building. Best practice would be to have a single main breaker as the Building Disconnecting Means but the code only limits the number of main breakers to Six.

Those are the high points. Do let us know if you have more questions.

Click to expand...

At the location near the service entrance and near the circuit breaker panel I driven and installed two ground rods at the required depth and required distance from each other. I was wondering about the impedance though, that is a good point; and nobody talks about it. As a matter of fact there are three ground rods near the circuit breaker panel (one is an old one that I decided to don't use unless needed).

So there is not need for an ground conductor in the garage. But then there is no harm in having a EGC (one ground rod only) near the garage building and connected to the subpanel. I have electronic sensitive equipment so I may install a EGC there. The old subpanel had a bus bar and a ground bar in spite of having no ground rod installed for the garage structure.

Hmm... The means of a main disconnect is not present at the moment; so I would need to have a main breaker or an extra disconnecting panel? And since the subpanel does not have a spot for a main breaker there is no main disconnect in the subpanel. But the subpanel is tied to the main circuit breaker panel at the house by means of a 60 amps circuit breaker, wouldn't that suffice as a main disconnect?

I will have a 30amps charging stations located inside the garage in order to charge a EV vehicle, and the other 30amps should be more than sufficient for my tools and lights.


Thanks for your insights!

JoeD said:

Conduit is require the full length of those wires, even inside the concrete walls.

Click to expand...

This is the underground conduit point of entrance bringing power to the garage.




It does not seem reasonable at all to expect someone to break through the wall to install a cable that is perfect fine and protected, and that was originally installed and passed all inspection at the time. Anyhow, I will not invite the inspector to my garage anyway.

Kabris said:

Non armored sealtite might work there too, but it still looks tight. Good luck.

Click to expand...

You mean liquid tight conduit? I don't believe -- and it is not reasonable -- for any inspector (most of the time they do a very superficial job and check the power outlets, ground, gfci functionality) to try to break through the wall to verify an installation that is perfect fine in all possible respects.

tk3000 said:

At the location near the service entrance and near the circuit breaker panel I driven and installed two ground rods at the required depth and required distance from each other. I was wondering about the impedance though, that is a good point; and nobody talks about it. As a matter of fact there are three ground rods near the circuit breaker panel (one is an old one that I decided to don't use unless needed).

Click to expand...

I was not writing about the Service Equipment at your house. I was only writing about the Garage Installation that you showed a photograph of. Now that you have written about the service equipment though I will point out that you should bond all three ground rods together even though one of them is older and seems superfluous. You don't want any conductive underground objects of any description left near to and yet unconnected to the Grounding Electrode System of your Service Equipment. The differences of Potential between two underground objects can cause a voltage gradient across the surface of the ground which would be dangerous to people or animals including family pets. One way to effectively raise the voltage across a piece of ground is to have underground conductive objects that are not bonded to each other that may cause the current flow from a lightning discharge to flow more strongly in one direction between the Grounding Electrode System; in your case your two driven rods; and an abandoned rod in its flowing out into the entire space around the strike until the discharge is dissipated.

So there is not need for an ground conductor in the garage. But then there is no harm in having a EGC (one ground rod only) near the garage building and connected to the subpanel. I have electronic sensitive equipment so I may install a EGC there. The old subpanel had a bus bar and a ground bar in spite of having no ground rod installed for the garage structure.

Click to expand...

The harm in having one rod only at your garage is that it would not be a code compliant installation unless the Single rod that you installed had an impedance to ground of Twenty Five Ohms or less. I'm trying to tell you that you must wire the garage's Building Disconnecting Means the same as if it were supplied by a separate service from the electrical utility. The only difference between the two installations is the formal name of them in the code. That would not be true if the Feeder included an Equipment Grounding Conductor (EGC) but your garage feeder does not.

250.32 Buildings or Structures Supplied by a Feeder(s) or Branch Circuit(s)
(A) Grounding Electrode. Building(s) or structure(s) supplied by feeder(s) or branch circuit(s) shall have a grounding electrode or grounding electrode system installed in accordance with Part III of Article 250. The grounding electrode conductor(s) shall be connected in accordance with 250.32(B) or (C). Where there is no existing grounding electrode, the grounding electrode(s) required in 250.50 shall be installed.

Hmm... The means of a main disconnect is not present at the moment; so I would need to have a main breaker or an extra disconnecting panel? And since the subpanel does not have a spot for a main breaker there is no main disconnect in the subpanel. But the subpanel is tied to the main circuit breaker panel at the house by means of a 60 amps circuit breaker, wouldn't that suffice as a main disconnect?

Click to expand...

As you can see by the language in 225.32 below the Building Disconnecting Means may not be located in another building except under exceptions that never apply to dwellings. Just like the Service Equipment and the Service Disconnecting Means at your house, your garage must have Building Disconnecting Means consisting of switches, breakers, or pullout fuse holders that can be turned off with no more than six "throws" of the hand. The required Building Disconnecting Means must be located either outside the structure OR inside "nearest the point of entrance of the conductors." The best remedy in your case is to buy a tie down kit made by the manufacturer of the panel that anchors a two pole breaker to the panel so that it cannot be removed without tools. That Breaker becomes your Building Disconnecting Means when you connect the two energized (Hot) conductors of your feeder to it's terminals so as to feed current from it's terminals through it's mechanism, through the buss bar clamps on that breaker's bottom, and into the buss bars to supply the remaining breakers which are connected to the buss bars.

225.31 Disconnecting Means
Means shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure.

225.32 Location
The disconnecting means shall be installed either inside or outside of the building or structure served or where the conductors pass through the building or structure. The disconnecting means shall be at a readily accessible location nearest the point of entrance of the conductors. For the purposes of this section, the requirements in 230.6 shall be utilized.

225.33 Maximum Number of Disconnects
(A) General. Th e disconnecting means for each supply permitted by 225.30 shall consist of not more than six switches or six circuit breakers mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard or switchgear. There shall be no more than six disconnects per supply grouped in any one location.

Exception: For the purposes of this section, disconnecting means used solely for the control circuit of the ground-fault protection system, or the control circuit of the power-operated supply disconnecting means, installed as part of the listed equipment, shall not be considered a supply disconnecting means.
(B) Single-Pole Units. Two or three single-pole switches or breakers capable of individual operation shall be permitted on multiwire circuits, one pole for each ungrounded conductor, as one multipole disconnect, provided they are equipped with identified handle ties or a master handle to disconnect all ungrounded conductors with no more than six operations of the hand.

225.34 Grouping of Disconnects
(A) General. The two to six disconnects as permitted in 225.33 shall be grouped. Each disconnect shall be marked to indicate the load served.

Exception: One of the two to six disconnecting means permitted in 225.33, where used only for a water pump also intended to provide fire protection, shall be permitted to be located remote from the other disconnecting means.

I will have a 30amps charging stations located inside the garage in order to charge a EV vehicle, and the other 30amps should be more than sufficient for my tools and lights.


Thanks for your insights!

Click to expand...

The panel appears to be Eight slot. Is that correct? If it is eight slot will the remaining six slots be enough for the loads you will have in the detached garage? The back fed main breaker is Two slots. Your charging station is One or Two breaker slots depending on whether it is 120 or 240 volts. Will the remaining Four or Five slots be enough for the loads you have planned?

tk3000 said:

This is the underground conduit point of entrance bringing power to the garage.

It does not seem reasonable at all to expect someone to break through the wall to install a cable that is perfect fine and protected, and that was originally installed and passed all inspection at the time. Anyhow, I will not invite the inspector to my garage anyway.

Click to expand...

What was never acceptable, under any addition of the National Electric Code (NEC), is to have your garage's feeder cable exposed to physical damage as it is were it comes up out of the ground and enters the void spaces in your cinder block wall. The depth of bury for cable in earth has been Two Feet since the first edition of the NEC. Since at least the mid Fifties of the previous century the NEC has required that the cable be protected from the bottom of the trench to the point of entry into the structure. How I would protect it now is to buy a piece or Schedule Eighty Non Metallic Conduit in the three or four inch size. Cut it in half lengthwise on a table saw, band saw, or with a Sawzall. Fasten that half shell of conduit to the garage footer from the bottom of the trench to were the cable enters the cinder block void. If, as seems likely to me, the footer is wider than the garage structure itself you will need to make miter cuts at the joint were the cable comes up over the footer and turns back to horizontal reach the wall so that the cable is continuously protected from the bottom of the trench to were it enters the cinder block void space. By doing that you will avoid the need to pull the cable down out of the wall so as to be able to run it through a conduit that has not been cut in half.

All that appears wrong on the inside is that you have let the Jacket of the cable slide back into the wall. The jacket of the cable should be clamped into a Service Entry Cable Connector which comes directly into a knockout on the back of the panel's enclosing cabinet. Alternatively it can come into a trough or large box; either of which should be just as deep as the panel cabinet itself; and then passes into the panel through a close conduit nipple or a chase nipple. If you are not too far along with the project just re-position the panels cabinet so that the cable connector can enter through the back wall of the enclosure.

Let us know if other questions arise.

Thanks for your thorough response.

Interesting point about the presence of an unbonded ground rod, I never consider this dop issue. The third ground rod should be very close to one of the new rods that I installed by judging from how the ground wire exit the ground, but I have to dig in order to find out the whereabouts of this old third ground rod. It seems that this old house circuit had ground added some point and it was applied to some outlets in the kitchen; this added ground circuit was obtained by one single ground rod and a clamp to the copper pipes (I am assuming it simply because I am not sure due to the fact that low life forms thieves entered the vacant house previous to me buying it and stole lots of the copper). As of now, ground by means of copper pipes is not an option any longer given that most of the pipes have been replaced with pex. Also, I will go ahead an install two ground rods near the garage; but the bare copper ground wire will travel a different path than the one used by the underground cable in order to enter the build; and I assume the bare ground wire does not need to be in a conduit (it whould be tucked away from the veiw and inconspicuous and so protected against mechanical damage)

“The harm in having one rod only at your garage is that it would not be a code compliant installation unless the Single rod that you installed had an impedance to ground of Twenty Five Ohms or less. I'm trying to tell you that you must wire the garage's Building Disconnecting Means the same as if it were supplied by a separate service from the electrical utility. The only difference between the two installations is the formal name of them in the code. That would not be true if the Feeder included an Equipment Grounding Conductor (EGC) but your garage feeder does not.*
“

Does the above implies that the lack of ground would be compensated by the main disconnect (means of isolation) is a substitute for a ground circuit? And in case, I had two ground rods properly installed and bond to the subpanel there would be no need to a main disconnect?

“
*The best remedy in your case is to buy a tie down kit made by the manufacturer of the panel that anchors a two pole breaker to the panel so that it cannot be removed without tools. That Breaker becomes your Building Disconnecting Means when you connect the two energized (Hot) conductors of your feeder to it's terminals so as to feed current from it's terminals through it's mechanism, through the buss bar clamps on that breaker's bottom, and into the buss bars to supply the remaining breakers which are connected to the buss bars.*
“

The subpanel I installed is a SquareD rather common one (got it for about $20 or $25) and bought some breaker switches. Is the tie down kit equivalent to having a main breaker inside the panel? If that is the case a main circuit breaker panel (a 100 amps ) could be used instead of a regular small subpanel.


“
The panel appears to be Eight slot. Is that correct? If it is eight slot will the remaining six slots be enough for the loads you will have in the detached garage? The back fed main breaker is Two slots. Your charging station is One or Two breaker slots depending on whether it is 120 or 240 volts. Will the remaining Four or Five slots be enough for the loads you have planned? “

Yeah, it is an eight slot subpanel. Is the back fed breaker equivalent to a the tie down kit you mentioned before, and does it take two slots in the subpanel? The vehicle has it own 120 Charger that can be hooked to any 15 amps 120v outlet, but I want to install quick charge stations that would require 220V 30 amps power (so it would take two slots). Most of my tools require 15amps or 20 amps, but chances are I will never be using many thing at the e same time; so 6 slots should suffice

“
What was never acceptable, under any addition of the National Electric Code (NEC), is to have your garage's feeder cable exposed to physical damage as it is were it comes up out of the ground and enters the void spaces in your cinder block wall. The depth of bury for cable in earth has been Two Feet since the first edition of the NEC. Since at least the mid Fifties of the previous century the NEC has required that the cable be protected from the bottom of the trench to the point of entry into the structure. How I would protect it now is to buy a piece or Schedule Eighty Non Metallic Conduit in the three or four inch size. Cut it in half lengthwise on a table saw, band saw, or with a Sawzall. Fasten that half shell of conduit to the garage footer from the bottom of the trencucture itself you will need to make miter cuts at the joint were the cable comes up over the footer and turns back to horizontal reach the wall so that the cable is continuously protected from the bottom of the trench to were it enters the cinder block void space. By doing that you will avoid the need to pull the cable down out of the wall so as to be able to run it through a conduit that has not been cut in half.*
“

The underground wire comes out of the ground via a conductor. Inside the cinder block walls it would be further protecgted against any mechanical damage and the elements. Where the underground cable emerge near the house (the o the end)close to main circuit breaker the underground cable emerge from a protruding pvc conduit and it is in fact unprotected and it is in fact a mess (but then I believe that it was the action of vandals and criminals during a time the house was vacant and I did not own it)

Above you mean cut the conduit half lengthwise so that it would like a semi-circle? At the garage end the conductors are protetected from the point where they exit the ground and then enter the wall via a pvc conduit. I believe that it is not protected inside the concrete wall (but I am not sure, at least it does not come up inside the garage with any sheathing or conduit otherwise). The garage was built in the 80s, and did no bring the underground cable to the garage or anything; I am simply rewiring (new wires, conduits, outlets, lights, etc). the interior of the garage and replaced the subpanel with a new one.

tk3000

tk3000 said:

Thanks for your thorough response.

Interesting point about the presence of an unbonded ground rod, I never consider this dop issue. The third ground rod should be very close to one of the new rods that I installed by judging from how the ground wire exit the ground, but I have to dig in order to find out the whereabouts of this old third ground rod. It seems that this old house circuit had ground added some point and it was applied to some outlets in the kitchen; this added ground circuit was obtained by one single ground rod and a clamp to the copper pipes (I am assuming it simply because I am not sure due to the fact that low life forms thieves entered the vacant house previous to me buying it and stole lots of the copper). As of now, ground by means of copper pipes is not an option any longer given that most of the pipes have been replaced with pex. Also, I will go ahead an install two ground rods near the garage; but the bare copper ground wire will travel a different path than the one used by the underground cable in order to enter the build; and I assume the bare ground wire does not need to be in a conduit (it would be tucked away from the veiw and inconspicuous and so protected against mechanical damage)

Click to expand...

If the Equipment Grounding Conductor (EGC) is not jacketed with Armor or enclosed in raceway you have to increase it's size to Number Four American Wire Gauge (4 AWG).

“The harm in having one rod only at your garage is that it would not be a code compliant installation unless the Single rod that you installed had an impedance to ground of Twenty Five Ohms or less. I'm trying to tell you that you must wire the garage's Building Disconnecting Means the same as if it were supplied by a separate service from the electrical utility. The only difference between the two installations is the formal name of them in the code. That would not be true if the Feeder included an Equipment Grounding Conductor (EGC) but your garage feeder does not.*
“

Does the above imply that the lack of ground would be compensated by the main disconnect (means of isolation) is a substitute for a ground circuit? And in case, I had two ground rods properly installed and bond to the subpanel there would be no need to a main disconnect?

Click to expand...

No it does not imply that. Both a Building Disconnecting Means and a Grounding Electrode System are required at each separate structure in all cases

“
*The best remedy in your case is to buy a tie down kit made by the manufacturer of the panel that anchors a two pole breaker to the panel so that it cannot be removed without tools. That Breaker becomes your Building Disconnecting Means when you connect the two energized (Hot) conductors of your feeder to it's terminals so as to feed current from it's terminals through it's mechanism, through the buss bar clamps on that breaker's bottom, and into the buss bars to supply the remaining breakers which are connected to the buss bars.*
“

The subpanel I installed is a SquareD rather common one (got it for about $20 or $25) and bought some breaker switches. Is the tie down kit equivalent to having a main breaker inside the panel? If that is the case a main circuit breaker panel (a 100 amps ) could be used instead of a regular small subpanel.

Click to expand...

Yes the tie down kit is equivalent to having a main breaker. The breaker that you will tie down using that kit becomes the main breaker. Yes you could use a main circuit breaker panel but since you already have the Main Lug Only (MLO) panel the tie down kit is your best remedy at this point. Find the Square D part number inside the panel cabinet and take that to any Square D Stocking Distributor. They can provide you with the correct kit to tie down the Two Pole circuit breaker which will serve as your Building Disconnecting Means (ie main breaker). In that way you will not have to go the hassle of returning the MLO panel that you already have.

“
The panel appears to be Eight slot. Is that correct? If it is eight slot will the remaining six slots be enough for the loads you will have in the detached garage? The back fed main breaker is Two slots. Your charging station is One or Two breaker slots depending on whether it is 120 or 240 volts. Will the remaining Four or Five slots be enough for the loads you have planned? “

Yeah, it is an eight slot subpanel. Is the back fed breaker equivalent to a the tie down kit you mentioned before, and does it take two slots in the subpanel? The vehicle has it own 120 Charger that can be hooked to any 15 amps 120v outlet, but I want to install quick charge stations that would require 220V 30 amps power (so it would take two slots). Most of my tools require 15amps or 20 amps, but chances are I will never be using many thing at the e same time; so 6 slots should suffice.

Click to expand...

The back fed breaker is the one that you will fasten in place by installing the tie down kit so that it can serve as the Building Disconnecting Means (Main Breaker). Since the feeder includes two energized conductors that have to be opened by the Building Disconnecting Means the back fed breaker will be two pole.

“
What was never acceptable, under any addition of the National Electric Code (NEC), is to have your garage's feeder cable exposed to physical damage as it is were it comes up out of the ground and enters the void spaces in your cinder block wall. The depth of bury for cable in earth has been Two Feet since the first edition of the NEC. Since at least the mid Fifties of the previous century the NEC has required that the cable be protected from the bottom of the trench to the point of entry into the structure. How I would protect it now is to buy a piece or Schedule Eighty Non Metallic Conduit in the three or four inch size. Cut it in half lengthwise on a table saw, band saw, or with a Sawzall. Fasten that half shell of conduit to the garage footer from the bottom of the trencucture itself you will need to make miter cuts at the joint were the cable comes up over the footer and turns back to horizontal reach the wall so that the cable is continuously protected from the bottom of the trench to were it enters the cinder block void space. By doing that you will avoid the need to pull the cable down out of the wall so as to be able to run it through a conduit that has not been cut in half.*
“

The underground wire comes out of the ground via a conductor. Inside the cinder block walls it would be further protected against any mechanical damage and the elements. Where the underground cable emerges near the house (the other end) close to main circuit breaker the underground cable emerges from a protruding PVC conduit and it is in fact unprotected and it is in fact a mess (but then I believe that it was the action of vandals and criminals during a time the house was vacant and I did not own it)

Above you mean cut the conduit half lengthwise so that it would like a semi-circle? At the garage end the conductors are protected from the point where they exit the ground and then enter the wall via a pvc conduit. I believe that it is not protected inside the concrete wall (but I am not sure, at least it does not come up inside the garage with any sheathing or conduit otherwise). The garage was built in the 80s, and did no bring the underground cable to the garage or anything; I am simply rewiring (new wires, conduits, outlets, lights, etc). the interior of the garage and replaced the subpanel with a new one.

tk3000

Click to expand...

I think that you may be mistaking the the Poly(vinyl chloride) (PVC) jacket of the Type USE cable for PVC Conduit. Both are made from Poly(vinyl chloride) but the cable jacket is much thinner and uses the flexible formulation of that plastic. Non Metallic Conduit (NMC) is often made from PVC but it is of a much thicker cross section and uses the rigid formulation of that plastic.

From the photograph that you posted the Feeder conductors appear to be in Type USE (Underground Service Entry) Cable. Cable of any type requires protection from physical damage from the bottom of the Two foot deep trench to eight feet above finished grade. The bottom line is that the cable that is showing in the photograph is required to be protected from the bottom of the trench until it enters the structure. Once the cable enters the building it is no longer required to have physical protection unless it remains exposed to physical damage. If that cable were installed on, instead of in, the interior wall of the garage it would be exposed to Extreme Physical Damage by the movement of Motor Vehicles. That may be why the original installer ran it inside the cavities in the block wall.

Again what I would do is to cover the cable from the bottom of the trench until it enters the wall with material having the same resistance to physical damage as Non Metallic Conduit. I would obtain that material by cutting through a length of Schedule Eighty Rigid Nonmetallic Conduit lengthwise. I would then relocate the panel's cabinet so that the indoor conductors enter through the back wall of the cabinet. I would install a chase nipple through the hole in the cabinet's back wall with an insulating plastic bushing on the end of it's threads inside the cinder block so as to protect the insulation on the feeder conductors from the rough edges of both holes through the cinder block and the wall of the cabinet.

"If the Equipment Grounding Conductor (EGC) is not jacketed with Armor or enclosed in raceway you have to increase it's size to Number Four American Wire Gauge (4 AWG)."

=> Yeah, I intend to use 4 AWG bare copper for the ground rods and will install two 10 ft copper 5/8 rods near the point wherein the underground cable emerge.

These tie down kits does not seem something one can find in any home center store. Is it also called "breaker retaining kit", like the following:

http://www.gordonelectricsupply.com...pFhoRa8OoncZRGY8Jr1jG1L2OWRYhDUf-zRoC7ePw_wcB

"The underground wire comes out of the ground via a conductor." Sorry, this was a typo. I actually meant that it come out of the ground via a conduit. A PVC conduit. The underground cable consist of three wires without any outer sheathing, and it indeed comes out of the ground via a rigid grey pvc conduit; so doesn't that mean that the cable is protected until it enters the structured and also mechanically protected while travelling inside the concrete wall, and thus the only a small section is exposed once it protrudes from the wall to then enter the circuit breaker panel? Do I need to protect this small section of exposed wires?

thanks!

The cable under the box does look like a convenient place to hang the trouble light. Whether it is code not, I would put a conduit over it.

tk3000 said:

"If the Equipment Grounding Conductor (EGC) is not jacketed with Armor or enclosed in raceway you have to increase it's size to Number Four American Wire Gauge (4 AWG)."

=> Yeah, I intend to use 4 AWG bare copper for the ground rods and will install two 10 ft copper 5/8 rods near the point wherein the underground cable emerge.

These tie down kits does not seem something one can find in any home center store. Is it also called "breaker retaining kit", like the following:

http://www.gordonelectricsupply.com...pFhoRa8OoncZRGY8Jr1jG1L2OWRYhDUf-zRoC7ePw_wcB

"The underground wire comes out of the ground via a conductor." Sorry, this was a typo. I actually meant that it come out of the ground via a conduit. A PVC conduit. The underground cable consist of three wires without any outer sheathing, and it indeed comes out of the ground via a rigid grey pvc conduit; so doesn't that mean that the cable is protected until it enters the structured and also mechanically protected while travelling inside the concrete wall, and thus the only a small section is exposed once it protrudes from the wall to then enter the circuit breaker panel? Do I need to protect this small section of exposed wires?

thanks!

Click to expand...

The item in the link that you included is the one you would need if your panel were a Square D QO type. Since it is instead Square D Homeline make sure you get the retaining kit for a Homeline two pole breaker. They are different! QO breakers use 3/4" slots for each single pole breaker and thus 1&1/2" for a two pole breaker. Homeline breakers use one inch for each single pole breaker and two inches for a double pole. Why the retaining kit is required is that without it a breaker can be removed from the buss bar in the panel and yet still be energized. If the breaker were to be closed when it was removed the exposed buss bar grips on the bottom of the breaker would then remain energized while accessible to human contact. The retaining kit can only be removed with tools so that removing it from the buss bar cannot be done by anything except a quite deliberate act.

In answer to your question YES, you do have to protect those feeder conductors anywhere that they are exposed to physical damage. As a practical answer all you need to do is protect the feeder conductors were they come out of the wall cavity. I would probably use a four inch by four inch by four inch deep box placed so that it can be nippled to the panel enclosure and cut a hole through it's back to install the largest chase nipple that would fit through the hole into the cinder block wall cavity. Only careful measurement on site will confirm that a 4X4 inch box will both cover the hole in the block wall and still line up with the bottom of the panel so as to permit the installation of the nipple between the box and the panel. If the panel cover that you have is the flush mount type that overhangs the box by a half inch or more on all sides then make sure you will end up with enough room for the cover between the 4X4 box and the bottom of the panel. Fit an insulating bushing to the end of that chase nipple that goes into the wall so as to protect the conductor insulation from abrasion on the nipple itself.

Or lower the panel so the cables could come thru a gromet in one of those back knock outs??????????