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Discussion in 'Electrical and Wiring' started by js5518, Dec 5, 2018.
sub inside next to main attached with conduit
The Grounded Current Carrying Conductor (Neutral) is not marked as required by the National Electric Code (NEC). It is not clear to me if the termination point on the buss bar that was used for the Neutral is actually large enough for that size of conductor. I notice that the larger add on lug which is specifically provided to terminate the Neutral is not used so I cannot help but wonder why. I cannot tell if the conduit nipple which was used to route the feeder conductors to the Feeder Supplied Panel is bonded to the Cabinet at each end. That may not be technically required by the NEC but it is certainly good practice. Best practice would have been a seperate Equipment Grounding Conductor (EGC) connected to the GEC buss bar in the second panel and to the Neutral buss bar in the house's Building Disconnecting Means enclosure cabinet. Bonding the Feeder nipple with Bonding Bushings would not only assure the electrical continuity of the nipple but also guard against any future corrosion of the contact between the Nipple and the two panel enclosure cabinets.
The thing that jumps out at me is that two terminals on the neutral buss were used to terminate a single stranded conductor. That is never a permitted practice under the National Electric Code because the terminals are not being used in compliance with their listing and labeling. There are add on lugs which are listed to be attached to the buss bar for terminating these larger conductors.
I'm also wondering were that bare stranded conductor comes from. Is it in the feeder from the house? I think that is were you said the Garage Feeder originates. Is there another conductor that serves as the Grounding Electrode Conductor (GEC) or is the split bare stranded conductor the GEC? A picture of the entire panel would be helpful.
There are a couple of possibilities here which may be useful now or in the future.
This may seem an off the wall question but were is the water pressure tank located, that is supplied from the well, and were is the breaker located which supplies power to the well pump and it's controls? I ask this because best practice with water pumps which may be used to supply water for first aid firefighting is to supply the pump with power from a source which is not located in any of the buildings which may need first aid firefighting effort. That is one of the reasons that separate well houses are often built to protect well heads and pressure tanks. If an additional disconnect were to be installed at the Service Disconnecting Means (SDM) location to power the water pump it is allowed to tap off it's supply from ahead of the 200 Ampere main breaker which is serving as the SDM. That still leaves you with only two breakers to shut off the service but it is worth knowing that the National Electrical Code specifically allows the disconnecting means for such a water pump to be excluded from the maximum of six switches, fused pull outs, or circuit breakers that can be used as the Service Disconnecting Means.
The second thing that occurs to me is that since you have another breaker space in the meter mains enclosure you could install an additional breaker to supply the detached garage. That would accomplish at least two things. The first would be to make more power available for the house as the Garage's load would not be going through the existing 200 ampere circuit breaker. The second would be to free up two breaker spaces in the panel which includes the Building Disconnecting Means for the house.
I do not see a bonding screw installed in this panel as a Main Bonding Jumper. I also do not see an Equipment Grounding Conductor (EGC) from the Feeder that goes back to the Service Disconnecting Means. That is because I am assuming that the bare copper conductor that terminates right beside the Feeder's Neutral Conductor is a Grounding Electrode Conductor (GEC). [Which may mean that "***/U/Me" is in play here. That means "To make an *** out of you and me."] Have I got it right or is that bare copper conductor the EGC from the supply Feeder? If there is no EGC run with the feeder from the Service Disconnecting Means (SDM) then there is no fault clearing pathway from the EMT which serves as the EGC for each of the circuits supplied by either panel in the house. One of the two fault clearing pathways must always be present! Either the Building Disconnecting Means enclosure cabinet is bonded to the neutral of a three wire Feeder OR the cabinet is connected to an EGC that is run with the feeder conductors all the way back to were the SDM's Main Bonding Jumper connects that EGC to the Neutral conductor of the Utility's Service Drop or Lateral. There has to be a way for ground fault current to get back to the secondary winding of the utility's transformer so that sufficient current will flow to quickly open the breaker of the circuit which has a ground fault. In the absence of that fault current path exposed conductive parts of the entire house electric system will become energized at or near 120 volts relative to any grounded conductive surfaces in the house. That means that several deadly traps could exist between those two kinds of surfaces all over the house just waiting for someone to touch one of each at the same time.
Tank is in the same room as the house main panel. The breaker is in this panel. The detached garage is not even close to that meter and not really any practical way to change. Not sure I follow on the Building disconnect? The house is disconnected with the 200 amp breaker in the house main? So this meter location is not bonded and would require the bonding screw in the house main panel?
Yes, that bare wire is the grounding rod for supply. Need to use bonding screw for that panel?
Yes, that wire needs to be moved to ground bar instead of the neutral bar. That goes to a ground rod, not from house. Does that neutral look bonded? Do I need to remove that center screw?
I definitely appreciate the help! Honestly my head is hurting...……………..Thanks
To Mark the Neutral conductor you can paint it white or grey where it is accessible. There is a product called "Liquid Electrical Tape" which is available in white, green, and red. I have found it easy to use for marking conductors and since it is made to insulate wires and is UL listed I can be reasonably sure that it will not harm the insulation. There are also paint markers with latex paint in them in quite a few colors. Latex paint is also safe to use on wire insulation. Alternatively you can simply apply a single wrap of white or gray electrical tape over the visible portion of the neutral conductor in each panel. That is really awkward to do once the wire is in place and energized. In this case you could simply open the breaker that protects the Feeder conductors from the panel cabinet which holds the Building Disconnecting Means to the adjacent Feeder supplied panel. You could then take the Neutral out of it's terminal lug to make taping it a lot easier.
I'm still waiting for you to tell us whether there is or is not an Equipment Grounding Conductor run with the other conductors of the Feeder from the meter mains Service Disconnecting Means to the house or from the house to the detached garage. I'm guessing that the feeder to the house was built before the National Electric Code required an EGC with feeders which supply separate buildings but I would like to have that confirmed. If the Feeder from the house to the garage was installed later it may have a EGC run with it even if the Feeder to the house does not.
So the question is Do four wires enter the house panel as the feeder from the meter mains assembly or only three. The same question again for the Feeder to the garage. How many wires are run. Is it three or four.
If there is no Equipment Grounding Conductor (EGC) run with the other Feeder conductors then you have to set up the Building Disconnecting Means exactly like a Service Disconnecting Means and install a main bonding Jumper in the Building Disconnecting Means cabinet to connect the Neutral Buss to the enclosure and thus connect any raceways which are connected to that enclosure to the Neutral. In the absence of an EGC run with the Feeder the Feeder Neutral must do both jobs of carrying the normal load current and carrying any fault current back to the Neutral of the utility's Service Supply Conductors and thence back to the secondary winding of the utility's transformer.
When there is an EGC run with the Feeder conductors then it provides the pathway for any current flowing from a fault to the non current carrying metal parts of the system back to the secondary of the utility's transformer. One of the reasons for using a separate EGC to carry fault current is that it eliminates the possibility of voltage drop or a high resistance connection in the neutral conductor raising the voltage of exposed non current carrying metal parts of the electrical system to a higher touch potential than is safe for the building occupants.
There are only 3 wires for both buildings. There is a rod at meter, house and garage. Sorry, thought I indirectly answered that.
I thought that was what you were implying but I needed to be sure. As I said earlier the code is carved in stone for that installation as the version in effect at the time the permit was issued. No one can require you to go back and change it now.
Bringing the Grounding Electrode System up to present code at each of those locations will not actually accomplish anything effective in improving the Grounding Electrode System's performance over what it is now. So don't bother putting in a second rod unless you are going to do the work to make the system more effective.
If you actually want to improve the Grounding Electrode System's performance then dig a trench that is 20 feet long between the existing rod and the new one. If the building has a basement or a deep foundation which extends more than four feet underground then you will also want to keep the second rod at least it's own length away from the underground structure. If the structure is too close to the property line to do that then get it as far away from the underground structure as possible. The trench should be at least 30 inches deep and deeper is better. So if you rent a mini backhoe and it's effective reach is four feet then you dig the trench four feet deep. Once the trench is dug then you drive the second rod through the bottom of the trench leaving just enough showing to connect the Grounding Electrode Conductor to. Install a Grounding Electrode Conductor of #2 AWG or larger bare copper in the bottom of the trench and use it in place of the code minimum #6 AWG. Use heavier style of acorn clamp to connect the #2 AWG to each of the ground rods. Replace the existing Grounding Electrode Conductor from the Service Enclosure or the Building Disconnecting Means enclosure to the first rod with #4 AWG. Back fill the trench and your done.
To get an idea of what you are building read the description of a Ground Ring in the National Electric Code (NEC).
"250.52 Grounding Electrodes.
(A) Electrodes Permitted for Grounding.
(4) Ground Ring. A ground ring encircling the building or structure, in direct contact with the earth, consisting of at least 6.0 m (20 ft) of bare copper conductor not smaller than 2 AWG." Copyright National Fire Protection Association (NFPA). Quoted under the fair use exception.
As you can see the installation which I am suggesting is the equivalent of a minimum length Ground Ring. Since it includes two driven rods that are more than six feet apart it also meets the NEC requirements for
"(5) Rod and Pipe Electrodes. Rod and pipe electrodes shall not be less than 2.44 m (8 ft) in length and shall consist of the following materials.
(a) Grounding electrodes of pipe or conduit shall not be smaller than metric designator 21 (trade size 3⁄4) and, where of steel, shall have the outer surface galvanized or otherwise metal-coated for corrosion protection.
(b) Rod-type grounding electrodes of stainless steel and copper or zinc coated steel shall be at least 15.87 mm (5⁄8 in.) in diameter, unless listed.
250.53 Grounding Electrode System Installation.
(A) Rod, Pipe, and Plate Electrodes. Rod, pipe, and plate electrodes shall meet the requirements of 250.53(A)(1) through (A)(3).
(1) Below Permanent Moisture Level. If practicable, rod, pipe, and plate electrodes shall be embedded below permanent moisture level. Rod, pipe, and plate electrodes shall be free from nonconductive coatings such as paint or enamel.
(2) Supplemental Electrode Required. A single rod, pipe, or plate electrode shall be supplemented by an additional electrode of a type specified in 250.52(A)(2) through (A)(8). The supplemental electrode shall be permitted to be bonded to one of the following:
(1) Rod, pipe, or plate electrode
(2) Grounding electrode conductor
(3) Grounded service-entrance conductor
(4) Nonflexible grounded service raceway
(5) Any grounded service enclosure
Exception: If a single rod, pipe, or plate grounding electrode has a resistance to earth of 25 ohms or less, the supplemental electrode shall not be required.
(3) Supplemental Electrode. If multiple rod, pipe, or plate electrodes are installed to meet the requirements of this section, they shall not be less than 1.8 m (6 ft) apart.
Informational Note: The paralleling efficiency of rods is increased by spacing them twice the length of the longest rod."
Copyright National Fire Protection Association (NFPA). Quoted under the fair use exception.
The combination of a Ground Ring which lacks only the encirclement of the entire building and the two driven rod electrodes at least six feet apart gives you a minimally complaint Grounding Electrode System under the NEC which is also a more effective system than most homes that do not have Underground Metal Water Piping have.
Tests done by the National Institute of Standards and Technology (NIST) show that the system I am suggesting is far more effective than the minimum required by the NEC [<25 Ohms or two driven rods] and sufficient to serve the protective grounding needs of most homes.
You definitely need to install the green screw in the First panel at the house. That screw is the Main Bonding Jumper for that building. That is the panel that has the building's main breaker; which the National Electric Code (NEC) calls the Building Disconnecting Means. Without that screw installed there is no Effective Fault Current Path.
Yes you need to use the bonding screw. Without it you will have no "Effective Fault Current Pathway."
Do not remove the center screw! It connects the Building Disconnecting Means enclosure to the Grounded Current Carrying Conductor (Neutral). It is part of the 'Effective Fault Current Path" from any "Ground Fault" that occurs in the garage. Without that screw any fault which occurs in the garage will raise the touch potential of all conductive surfaces in the garage to the system voltage of 125 volts to ground. Since the concrete floor of a garage is usually conductive the absence of that Bonding Screw would set up a deadly trap for anyone who touched the metal face plate of a switch.
The Neutral is bonded because the Neutral Buss is bonded to the enclosure by that Green Screw.
In a building supplied by a Feeder that does not include an Equipment Grounding Conductor the Neutral buss and the Equipment Grounding buss are one and the same. That is why the Neutral Buss must be bonded to the enclosure so that any raceways or metallic cables which are connected to the panel's cabinet will also be connected to the neutral to provide an effective fault current path.
No the Grounding Electrode Conductor does not need to be moved to the Equipment Grounding Buss. It just needs to be terminated to the Neutral buss in the correct size lug.
So, the only thing that needs to be done in this box is use large lug for the bare stranded wire, but leave on neutral buss bar?
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