Hi folks, I’m wondering if anyone has or can steer me towards a good, detailed diagram of an electric panel (residential). I would like to have this info handy to show clients, (since I can’t have them touching anything!) as well as for myself. What i need is something that shows what the wires are, where they’re going, what’s hot, neutral, the bus bar, breakers/fuses, etc… If anyone has a good jpg or can send me a link I’d really appreciate it. I’ve tried google pics to no avail…
Might not have exactly what you’re looking for. But lots of good stuff.
[size=4]David, thanks, that’s a good pic. If you happen to find some others, or a good website for this kind of info, let me know. More detail is good, but than again, not an INSANE amount of detail, haha… Just trying to be as educated as i can be, without going overboard. Thanks again. :D[/size]
Electrical is my week point as well. Thanks for the great illustration David. Does anyone have a good checklist for what HI’s should identify and call out? Another words should one be doing a inspection as indepth as a licensed electrician would?
Don’t typically see 4 wires in the SEC power feed, tho.
I’ve got a very in-depth electrical checklist, but I can guarantee that I’ll receive all sorts of negative feedback regarding this checklist. For those nay-sayers out there…“This safety checklist may not be for everyone, but it is simply a generic list of electrical safety items”
**Removing the panel cover **
Caution should always be taken when removing the cover for a panel. I suggest a good pair of gloves that are insulated when doing this just in case…something is grounding out to the cover as you remove it. I use leather gloves, although nor insulated, but easy to work with.
Be sure you are not grounded in any way when removing the cover. A good safety shoe or boot that is insulated works a lot better than your average pair of Nikes.
When removing the screws to the cover keep one hand in the center of the panel so it does not twist or slip as you loosen the screws. Once all the screws have been removed, slide your hands in place to the sides of the cover, as you keep pressure on the cover. Then remove the cover by pulling it straight back. Do not pull one side or the other of the cover when removing for this may cause breakers to trip. Also if there are any exposed wires inside, they may come in contact with the cover as you remove it in that fashion.
Once the cover is removed, set it aside where it cannot be accidentally kicked or knocked over.
**Inspecting the inside of the panel **
Get a good light and shine it on the inside of the panel but do not put it so close that it can come in contact with any wiring in the panel, especially if it is a metal flashlight. You should be able to inspect all points of the panel without coming in contact with any of the external wiring.
Most newer panels have lugs at the top where the main feeders come into the panel. These points are extremely hazardous to work around if you have no experience with panelboards. At any given time there could be enough current at those points to definitely do a number on your hair, as well as your entire body. When looking at these feeders, you should be able to trace them to where they enter the panel. However in some cases, the other wires may cover them up to make them “hidden”. DO NOT pull away the other wires to expose the main feeders. One never knows what lurks on the other wires. There could be skinned wires which expose the conductor and as you grab them to pull them away…WHAM!
Some panels have the main feeders going to a breaker. The only thing you need to know about this breaker is that it is commonly referred to as the MAIN, or MAIN BREAKER, or MAIN DISCONNECT. It must have either a screw in the middle of it or some type of bracket holding the breaker in place. This will prevent the breaker from falling out of its place, which can typically be caused by the main feeders being large in size and putting pressure on the breaker itself. If there is no bracket or screw securing this breaker…write it up and be very, very careful while inspecting the panel and when replacing the cover. If it is NOT secured, this breaker can at any given time, “POP” out of its place. When such happens it will cause many arcs and sparks as well as killing power to the house. If it should POP out…contact a sparky to put it back in place. DO NOT try to put it back in place yourself…unless of course you have a death wish.
The neutral wire or return is often colored with white tape, but it can also be gray, or just stranded wire that is bare. Some times it can even be NOT marked. Although in most cases the neutral conductor is safe to touch, it is NOT recommended to do by a HI, unless the HI has had specific training with such. At any given time when you have your hands inside of a panel, you can draw a arc to your body, especially if you are grounded in some way. IT IS NOT A GOOD PRACTICE to stick your hands inside of a panel in any way if you are not sure of what can definitely kill you inside. Inspection can be done visually and not by physically touching anything.
On the branch circuit breakers, the wires leaving them are HOT or LIVE. Touching any of the metal parts of the connection on the breakers can cause electrical shock. In the case of double taps on these breakers, simply note it but do not touch the wires to see if they are loose. If they happen to be loose and you grab unto them, you can pull them from the breaker, thus resulting in a arc if there is significant current flowing thru the wire. Remember, voltage will shock you but amperage is what kills you.
Check the neutral bus of the panel and insure it has a neutral wire going to it. If this is a main panel board, also verify that a Equipment Grounding Conductor (EGC) is going to this bus bar. This EGC is commonly bare copper, but can also just be a piece of wire. It should be marked with green tape if it is a piece of wire, but then that may not always be the case. The ground is safe to touch but again it is not recommended to do. The EGC must go to a ground rod and be attached within 5 feet of where the water enters the house. In rare occasions, such as when a well is used, it may not be possible to bring the EGC to the entrance point of the water to the house. Also if PVC pipe is used to bring the water into the house from underground, there must then be two ground rods, placed 6 feet apart versus a single ground rod and a water bond.
You may see splices in the panel as well. Do not touch these for you have no clue as to the integrity of those splices. These too can come apart at any time especially when handled. Overall, if you MUST put your nose pickers in a panel, be careful of grounding yourself. It is possible to touch a hot connection and not be shocked if you are not grounded, but this is a experiment that any HI should NOT be exploring. Wear gloves and even if not insulated ones, they will somewhat protect you from electrical shock. Wear long sleeves as well and ALWAYS remove all jewelry such as watches, rings, etc.
You do not need to be verifying the tightness of any connection inside of a panel. Typically if a connection is loose, you will see that it is discolored from the other connections. It may lose it’s sheen as well and appear dull. There may also be corrosion built up on it. The insulation of the wire connected to it may also be melted or distorted from heat buildup. If you notice any of these things, recommend inspection by a sparky. DO NOT touch the wire to see if it is loose. This can also be a hazardous practice. On aluminum connections, verify the presence of a anti-oxidant compound. Usually this can be done by looking at it. It us typically black or gray in color and rarely clear. Either way it will look like grease on the bare conductor part of the wire. If it cannot be seen, do not move the wire to see if it is there. If you cannot verify that it is there, recommend inspection by a sparky. Best to be safe…than to be sorry.
NEVER stick anything metal into a panel. If you must stick something in the panel, make sure it is insulated. Inspection mirrors should be made of a non-conductive material such as wood or plastic. A magnifying glass may be used but again must be of a non-conductive material.
Replacement of the cover
Open the panel door and place the cover straight on to the panel itself aligning the breakers to the cut outs on the cover. Do not twist the cover as you put it on.
Holding the cover firmly against the breakers and enclosure with one hand, replace the panel screws by starting them all in their respective holes, but do not tighten any specific screw until all are in place. Often panel covers do not line up with their holes for securing the cover. If you tighten one or two down, you may not be able to line up all the holes. After you have all the screws started in their respective holes, tighten the screws down.
Before putting cover on though, verify that no wires are sticking out of the panel, where they can be easily pinched with the cover. If you must push wires into the panel to prevent them from being pinched, it is recommended that you do such while wearing gloves, or softly pushing on them with a piece of wood or plastic. DO NOT jam the wires in place or push on them unnecessarily. If you have to push them back in do so gently.
NEVER use pointed screws in a panel cover and if pointed screws were removed…do not put them back in. Pointed screws can nick and cut into the wires in the panel thus causing a short which can result in a arc, a explosion and even a fire. The ends of the panel screws should be rounded or flat but not pointed. The should also be no more than 3/4" long. Any screw longer than this can potentially make contact with live wires in the panel.
Insure that the breakers are lined up with their slots before tightening the panel screws. Once all screws are in you can tighten them down to a point where the cover can be easily aligned with the breakers but will not slip or move sideways. Once you have the breakers lined up with the holes in the cover, keep pressure on the cover as you tighten the screws down.
**Grounding yourself **
The metal on the enclosure of a main panel must be grounded. In some cases it may not be but it should always be assumed that it is. If you grab the metal part of the enclosure with one hand, or even brush against it with bare skin as you touch any live part in the panel, you can potentially complete the circuit and be shocked or even electrocuted. Wearing long sleeves and wearing gloves will help protect you from grounding yourself. Also realize that any metal around the panel can potentially ground yourself and put you at risk for shock and/or electrocution.
**General Tips **
It is a code violation not to have a light near the panel. If there is none…provide some sort of lighting before even attempting panel cover removal and/or panel inspection. Also make sure that there is at least 36 inches in front of the panel before attempting any sort of inspection. If the panel is in a cramped area or in a closet or in any area where it would be difficult at best to get to it, it is recommended that you do not open the thing but rather recommend inspection by a qualified sparky.
If there is a shelf or a washer or dryer in front of the panel, this does not give you the 36 inches required. One cannot safely open this panel up if they are leaning over a washer or dryer or cabinet or shelf. Removal of these items should be done prior to attempting any sort of inspection of the panel.
If by some chance you see another individual that has completed the “circuit” and is in contact with live power, DO NOT grab him with your bare hands for you will then become part of the “circuit”. Grab a broomstick (non metal) and place it around his abdomen and pull him off of the panel, or a belt can work too, or you can even tackle him away from the panel much as you would tackle someone in football…thus pushing him off the circuit.
Never work on a electrical panel while standing in water or around very damp areas. If such is present it is better to recommend inspection via sparky versus yourself.
**Main Disconnects **
At times, there may not be a main breaker disconnecting the service equipment. Instead a fusible disconnect may be used or a disconnect using a knife switch. In any case, inspection of these items must be done with extreme caution.
Typically the door to the disconnect can be opened without shutting the disconnect off, however, as a HI, you should determine if you can shut the disconnect off prior to opening it up. If such is not possible, there is usually a release for the door so that it can be opened while power is on. Sometimes it may be a screw that needs to be turned or a small screwdriver has to be placed into a slot to push up a lever. If you are unaware as to how to open a cover on a disconnect…do not even attempt it. If you try to slide a screwdriver into the slot and have no clue what you are doing, it can be quite hazardous to your well being.
If you manage to get the cover opened, do as you would with the electrical panel and do not put your hands inside. Some disconnects will have fuses while others may use just a knife switch. All you need to be inspecting is that the feeders coming in to the disconnect are connected to the right terminals, and the feeders leaving as well. Inspect the connections visually for looseness and corrosion. Typically the fuse size can be seen but if for some reason they cannot, DO NOT attempt to turn the fuse to see it. There is voltage and current at those fuses and touching them can cause electrical shock. Even if the disconnect has been turned off, there is no way of being sure that all power is off those fuses. It could be that the disconnect was back fed…thus meaning there is voltage present at the fuses.
In the case of a knife switch, the same holds true. NEVER out your hands in any type of disconnect unless you have been trained to do so.
Once you have inspected the disconnect, you should be able to close the door, even if it is on. Note that some disconnects may have a cover that needs to be removed to see the insides. If there is, be extremely careful not to “dip” the cover into the enclosure, for doing such can cause contact with live parts. At all times try to remove it by pulling it straight back.
Where the main feeders attach in the disconnects is where live power exists. If the disconnect is on, the fuses or “load” side of the knife switch are also live. Again, unless you specifically know that the disconnect is not “back fed”, and unless you have been trained to work on such equipment, do not EVER attempt to put your hands in these types of enclosures. They are often small in respect to the wires and fuses, and can be exceptionally hazardous to touch anything inside of them. DO VISUAL inspections whenever feasible.
**Be careful and always be alert in what you are about to perform on an electrical panel or disconnect. One false move can be your last!! **
Thanks a million David. By chance any pictures for the different areas your talking about to help give a better understanding?
Ok just read it. Great info!! Now do you have one that just follows the SOP or can you make one with information regarding the areas we should be focused on or looking out for other than safety?
Typically…two (count 'em,–) two black wires (Hot) to the main breaker.
one (by actual count) white wire (Neutral) to the neutral buss (where else?).
one set of stranded wires twisted tightly (for the most part) and secured to the neutral buss to ground the system (sort of).
2 + 1 + 1 = ?
One should also see **two **1/4 bare wires in the panel–one to bond the water line and one to the earth-ground rod outside.
Ok I’m taking notes keep them coming
Are you gonna report us???o
Nope not one bit. Just building me a checklist.
Great tag line by the way I use it to it’s actually landed me jobs!
Oh, good…I thought for a moment there I was going to have to move again…:):)
So Jae do you have a good checklist for the electrical panel?
Only in my own mind.
I’ve been at it so long it just hangs around rattling in my brain. Nothing written, all rotten.
Dave’s list is good. If you read it a few times, and truly understand the content, then you could write your own checklist.
And here’s a little something that DV offered one time some years ago, I believe. At least I hope he offered it, because I took it.
I edited his original and use it to explain sub-panels…
A SUB-PANEL, or REMOTE DISTRIBUTION PANEL, is merely an extension of the main service panel. Since the neutrals are bonded to the grounding wires in the MAIN SERVICE PANEL, the grounding wires (bare) and the neutral wires (white) should never be connected in any manner beyond the main panel. However, the grounding wires should be bonded to the sub-panel.
And “objectionable current” may flow on metal parts (grounding wire or metal conduit) when the grounded neutral conductor (white wire) is bonded to the metal case of a panel-board that is not part of service equipment (such as a sub-panel). Occasionally, the wires may come in contact with each other in their jacket causing a short circuit in the grounding/grounded system.
[If a neutral wire became disconnected (and, it does happen), the return path for electric current could be along a ground wire. While that itself may not always be a hazard, if that ground wire also became disconnected somewhere, parts of the ground system could be energized. That is NEVER** supposed to happen.] **
The neutral wire is essentially a “low-risk” return path for the electric current in that branch of the system. All of the neutral wires have the same electrical potential…zero. At least, no potential compared to ground. There is, of course, 120 volts of potential difference between a neutral wire and any hot wire in the average residential system.
If one were to touch the metal part of a live neutral wire one should not receive a shock. (Don’t try it!) By tying the neutral to ground at one point (in the main panel), half of the conductors (in a typical 120 volt circuit) have no dangerous electrical potential. Of course, as always, the hot wires are still dangerous.