These are some of the questions asked and answers given when this website was accepting questions. The reason this website stopped answering electrical questions was because of the enourmous amount of junk mail recieved. If you surf this site and the links, or go to the Search Page , you should get most of your questions answered.
Q.... It seems that a lot of these houses have 15 amp devices (plug & switches) in the kitchen & dinning room on a 20amp wire & breaker. Is this OK according to the NEC?
A....The code allows this as long as you treat the circuit as 15 amps. In other words no more than a 12 amp load on the circuit with a 15 amp receptacle.
Q....Is it true that you should not keep turning your lights on and off because it costs money.
A....For regular incandescent household bulbs, if your not using them, turn them off. You are only charged for these bulbs when they are on. For fluorescent bulbs if you are going to use them in a few minutes leave them on. Frequent turning on and off for short periods of time can reduce the life of a fluorescent lamp. Never leave them on when leaving the house.
Q....How can you tell the temperature rating of Romex used to feed lighting fixtures?
A....Look for the letters NMB on the jacket of the wire. The NM means nonmetallic sheath cable (Romex) and the B suffix means that the cable's conductors are rated for a maximum operating temperature of 90°C 194°F.(Article 336-30-(b). We can assume that wiring made prior to 1984, without the B suffix, is rated at 60°C 140°F. This is the type of wiring found in most older homes that were built before 1982.
Q....We want to know if the INFRARED SCAN is accurate in determining or predicting panel failure.
A....The Infrared Scan has a degree of accuracy and can check electrical panels for hot spots , defective transformers and loose electrical connections.
Q....On a circut/outlet tester what does open ground...open neutral...open hot...
hot/ground reverse...hot/neutral reverse actually mean Thanks for taking the time to answer.
A....The ground stands for the equipment grounding wire (green). The neutral is the return wire (white). The hot wire is the live feed (black). An open means the wire is either broken, disconnected or was never there. Reverse means exactly that.
Q....Can you tell me what reverse polarity is and if it is or is not dangerous?
A....Reverse polarity in Alternating Circuits is when the hot/neutral wiring is reversed. Yes this could make the neutral live and present a shock hazard.
Q...This web site is all basic bare bones electrical knowledge that I learned in my first year of training. If you don't answer electrical wiring questions than this site is useless.
A...Maybe this site is not for people with advanced electrical training like yourself. Not everyone is as smart as you are when it comes to basic electrical knowledge.
Q....I'm a sixth grader and have a science question. Why do the pronges, on an electrical plug, have holes in the metal? Thank you for your time.
A....Allthough not used much anymore the holes on the end of the prongs were used as a lockout so defective or electrical devices being worked on could not be plugged in. Either a wire with a lock on the end or a thin shaft lock was used and placed through the holes.
Q....I'am a electrician in south Florida, about to go for my journey mans and a bit nervous. I have a few questions for you.
1. What is the corona affect?( not the beer)
2. What is conductance MHO of a circuit?
A....Powerlines carry electricity at high voltages and the electric field strength near each powerline cable is often sufficient to ionise the air. This creates streams of ions which are emitted into the air. Such ions are known as corona ions or simply corona. You can often hear the characteristic ‘fizzing’ sound of powerlines emitting corona.
Conductance is the opposite of resistance. The unit for conductance is expressed as the word ohm spelled backwards which is MHO.
Q....Perhaps it's better not to offer only partial info. about the topic, but I thought a few items might be of interest.
Apparently, the problems happened when Al wire was used with screw terminals in outlets, etc. designed for Cu wire.
Temperature changes and the different coefficients of expansion, I've read, caused initially-tight connections to loosen, letting air contact the Al, and as Al will do, it very quickly oxidized. That created high-resistance connections.
I read, some time ago, about terminals designed specifically for Al wire (and Cu, as well); I think they were marked "Cu/Al".
Btw, your Web text needs copy editing! It's clearly written and understandable enough, which is more than one could say for a lot of Web text. However, there are many small items, including misspellings, that need fixing. After all, you were an electrician, not an editor!
Best regards, [nb
A....As an editor I leave much to be desired but I am a pretty good electrician. Bob.
Q....I have seen pictures that show how to add a ceiling light in retrofit work where they make an opening at the top of a wall and at the bottom of a wall, and fish NM cable up between two studs and staple the cable only at the top and bottom-- how does this get by the every 4" staple rule.
A....Article 336-18 of the NEC. states that concealed work in finished buildings or concealed paneling where supports are impractical it is permissible to fish cable to access points.
Q....How does 208/120 volt system work versus 120/240? I get 120v on each leg but when combined, 208.
A....The single phase system has two poles 180° out of phase, the three phase system has three poles which are 120° out of phase. The voltage between the Hot and Neutral is 120 volts in both, but because of the phase angle, the voltage between any two hot wires in three phase is 208 volts.
Q....What do the terms..open and close a circuit mean/ thanks
A....An open circuit is one where no current flows. A switch in the off position would indicate an open circuit.
A closed circuit is one where current flows. A switch in the on position would indicate a closed circuit.
Q....If a short happens in a residential circuit it goes to ground ,but it also trips the breaker, how does this do both? the hot is connected to the breaker, how does a return path go back to the breaker? please reply,thank you!
A....A breaker trips when the ampere load exceeds the breakers rated value. A dead short on a circuit can cause hundreds or sometimes even thousands of amperes to flow for a short period of time thus tripping the breaker.
Q.... I have a light dimmer switch that broke such that it won't turn off when I push it in. By turning the dimmer control I can cause the lights to go out. Is electricity being used when I have the dimmer turned all the way down? I am leaving to go on vacation and want to know if I can should have the switch replaced today or can I wait until I return (without using a lot of electricity while I am away). Thank you.
A....It might not use much electricity, but it is not a good idea to leave broken electrical devices unattended for any length of time. Broken contacts can cause arching and overheating.
Q....If the 3 prong outlet on the top of my stove tests "open ground" with an electrical tester, does that mean my stove/oven is not properly grounded?
If so, what would be the impact of this?
A....It usually means the ground is disconnected or not there at all. If there was a short circuit to the frame of the stove instead of going to ground it could go through a person touching the stove.
Q....What is an inverter and how does it work?
A....An inverter takes DC power from a 12-volt battery and converts it to household AC power, making it useful for operating all kinds of devices. Electric lights, laptops, TVs, radios, power tools, kitchen appliances and office equipment are just a few of the applications that can be operated with an inverter. Depending on the type, it is run by a battery and running lenght is a problem.
Q....Using Ohms Law to find resistance in a 40watt, 120 volt light bulb I get 360 ohms. But when I check it with an ohmeter I get 23 ohms?? Why
A....Thats because the light bulb is off. When the bulb is on the filament is heated and there is a change in the resistance.
Q....In our home when we plug an iron into a 15 amp circuit the iron draws 8 amps (we measured it with an ampmeter). When the iron is on and drawing the 8 amps, the overhead lights on that circuit go dim. The measured voltage at the outlet that the iron is plugged into drops from 119VAC to 111VAC when the iron is on. Is this correct behaviour, or is there something wrong with the wiring?
A....Your lights could dim if the wiring in the circuit is not large enough, it will have too much resistance. When a large current is present in the wire, there will be a significant voltage drop, leaving less voltage available to your lights. In others words you could have to much of a load on that size circuit.
Q....Reference FAQ #16. What does it matter if the air has atoms with electrons unless you are interested in an insulator. It is the atoms in the conductor that have an odd number of electrons in the outer shell of the atom which allows the voltage (pressure) to move electrons from atom to atom. The air has an even number of electrons in the outer shell and is a fair insulator.
A...This website is not interested at this time to get into the entire theory of how electrons are derived from atoms. This can be obtained from many areas on the web. We are only interested in the very basics so that everyone can understand without being bored. Thank you for your input.
Q....We have a 100 amp service, but the breakers add up to 150 amps. Is the service overloaded?
A....Your breakers are there to protect the branch circuit wires. (15 amp breaker for #14 wire etc). They are not primarily used as overeload protection for your electrical devices. Each breaker will probably use less than half its amperage rating. To find out if your service is overloaded you will need to have a load check taken with an ampmeter.
Q....Fine website, and thanks for making it available to us.
Suggest a change to a paragraph in the link on the Neutral Wire.
It presently reads: " If the equipment is grounded, the resistance of the path through the grounding conductor will usually be much less than the resistance through the stray path, and much current will flow through the stray path. Sufficient current will usually flow through the grounded path to blow the circuit fuse or trip the circuit breaker and thus open the circuit. On the other hand if the equipment is not grounded sufficient current will flow through the stray path to be a shock hazard."
Recommend it reads: " If the equipment is grounded, the resistance of the path through the grounding conductor will usually be much less than the resistance through the stray path, and NOT much current will flow through the stray path. Sufficient current will usually flow through the grounded path to blow the circuit fuse or trip the circuit breaker and thus open the circuit. On the other hand, if the equipment is not grounded, sufficient current will flow through the stray path to be a shock hazard."
A....Thank you for the correction. It has all ready been changed. Try to get everything right before entering it, but with so much information to put out I sometimes make mistakes. Thanks Again.
Q....Re: How safe is aluminum wire? Bob, Thanks for the information you've made available on your site. If possible, you may want to update the information regarding aluminum building wire. Nearly 95% of residential homes built today are using aluminum cable for Service Entrance. The aluminum building wire in use today (the only one approved by the NEC) is the 8000 Series aluminum alloy. Even though this cable is approved for sizes 12 AWG and larger, no manufacturer produces sizes smaller than #8 (for SEU cable)and #6 AWG for single conductor.
I agree, that if someone has aluminum cable in a house older than,say, the mid eighties, chances are it is NOT 8000 series. The previous product was actually the same aluminum utility cable (EC1350) that is still used on power lines today. However, it was a mis-application to bring this product into a house for switches and receptacles. The Aluminum Association, along with cable manufacturers, and CONNECTOR manufacturers set out to rectify this problem, resulting in the 8000 series alloy in use today. Here in Florida, projects ranging from single family homes to Raymond James Stadium, are incoporating 8000 Series for electrical feeders. Just thought you should know.
A....Thanks for the input. Good to hear both sides.
Q....I recently moved to a 2 bedroom apt.with 3 airconditioners, one in each bhedroom and one in living room. The fuse blows when 1 bedroom airconditioner is on at the same time as the living room. The handyman said this is because they are 15 amp fuses and should be changed to 20 amp s each in the box. Does this sound correct, and who should do it, and how expensive is it?
A....A 15 amp circuit requires #14 wire which is the rating for a 15 amp fuse. A 20 amp fuse is for a 20 amp circuit which requires #12 wire. If you put a 20 amp fuse in a 15 amp circuit (#14 wire) you could burn up the wire before the fuse blows. The reason the fuse is blowing is because there is to much on the circuit.
Q....Will the N.E.C. allow a light fixture to be hung 7' over a bath tub?
A....According to Article 410-4 (d) No parts of cord connected fixtures, hanging fixtures, lighting track, pendants, or ceiling suspended fans (paddle) shall be located within a zone measured 3 feet horizontally and 8 feet vertically from the top of the bathtub rim or shower stall threshold. This zone is all encompassing and includes the zone directly over the tub or shower stall.
Q...I have a 400 watt metal halide street lamp set up on 120 volt ac. If I switch the ballast over to 220-240 volt ac will that reduce my electric bill since the light will only be using half the amps at 220?
A...Not really. Your bill is based on kilowatt hours, Watts = Volts x Amps. Ex. If you 240 volts at 10 amps. It will equal 2,400 watts or 2.4 kilowatts. If you have 120 volts at 20 amps, you will still have 2.4 kilowatts. A 400 watt bulb at 240 or 120 volts will still be 400 watts.
Q...What is the definition of electrical demand,what is its unit?
A...The amount of electricity that is used at any given time is called the demand for electricity. In small quantities electrical demand is measured in watts , and in larger quantities it is measured in kilowatts (The k stands for 1,000 W).
Q...What is the use of this website. I asked a question and did not receive an answer?
A...Chances are your e-mail address was incorrect. I really dont have time to track down e-mails.
Q....I am not an electrician, but I have been doing my own wiring in new construction and old for the past 15 yrs. I have had no problems cause I have asked experts on how to wire things up. If you will not answer questions on how to wire things up, why do you have this site? Your advice is nothing more than what someone can get from a book. I have a do-it-yourself book that shows you how to wire receptacles and lights and they are pretty clear on the how to part. Not everyone can afford a licensed electrician at any price. We are basically gutting our old house and putting in new insulation, wiring, drywall etc. I am not going to pay an electrician $30 an hour to run wire to the lights and receptacles which I can do myself. But sometimes us dumb people that don't have a license need help now and then. All you do is help your fellow electricians make more money than they deserve. Too bad you won't answer questions from people who just want to save money and keep the cost of living at a minimum. Do you ever do any maintenence on your own vehicle Bob? Shame on you if you do, you should take it to an expensive mechanic to do your work. Do you have a mechanic's license? I don't think so. You could put the wrong oil in your own vehicle or whatever. Is that the price you put on your family's life? Sorry, but I had to say all this, I am tired of people who think that just because they have a license, that anyone who doesn't is stupid and can't follow directions.
A....Wow! I guess you told me. Heaven forbid I would never consider anyone as stupid because outside of the electrical trade I am not very bright myself. First thing is I never lift the hood of my car. This is left to mechanics who are experts at their trade. I don't pull my own teeth or operate on myself either. You probably are very good at electrical work but how do you know the one thing that a trained person might know to prevent an accident you might not know. This is one of the few negative e-mails that I have received. If you noticed my purpose for the web site is explained in detail. If you knew the training and time required to become an electrician you might see things differently. Just as I am sure you will never change your opinion of electricians I will never change mine on hiring a professional to do electrical work. Everything aside thank you for your input.
Q...Hi Bob---this is a great site you have. I am an ASHI certified home inspector and am just amazed at the stuff I find in panel boxes, attics, etc, installed by Mr Iwunnabean electrician. It amazes me that some of these houses are still standing!! keep up the good work.
Q...Good site. Smooth and open pages with usable links. Accurate information and not afraid to show all the FAQ's. I thought I knew it all and with your page it's a shoe in.
A...Thanks. (have to put some compliments on this page every so often).
Q...Hi I was wondering if you can tell me the conversion of watts to amps.(ex. 300 watts = ? Amps.)
A...You need to know the voltage also. Watts = Volts x Amps. Click on Ohms Law for more information.
Q...Send me step by step information on how to wire my basement, starting from the main panel. I have done quite a bit of electrical wiring.
A...I am sure you are very good in performing electrical work, but I cannot give actual wiring electrical advice until sure that the person doing the work is certified or licensed. Hope you understand.
Q....Thank you for your explaination of the National Electric Code it was most helpful. My question is, what is the difference between the National Electric Code and the National Electric Safety Code?
:A....The National Electric Safety Code covers supply and communication lines, equipment, and associated work practices employed by a public or private electric supply, communications, railway, or similar utility in the exercise of its function as a utility.
The National Electrical Code addresses proper electrical systems and equipment installation to protect people and property from hazards arising from the use of electricity in buildings and structures.
Q....Could you give a ballpark figure of what the cost would be to upgrade to a 200 amp panel and also what the cost would be to rewire an entire house.
A....Depending on the layout of the house upgrading to a 200 amp service could cost anywhere between 800 to 1,500 dollars.
Rewing an entire house, again depending on the layout of the home could cost between 2,000 and 4,000 dollars. These are just rough estimates.
Q...The power for the outlets in my kitchen and garage dont work. I reset the circuit breaker still nothing. What could be the problem?
A...You might want to check for a GFCI. (Ground Fault Circuit Interrupter) receptacle that needs to be reset. This receptacle would have a test and reset button. The reset might need to be pushed in.
Q...Checked your website and found some mistakes with your code interpretations. From a real electrician.
A...Wow! A real electrician. Have to check my Massachusetts license to make sure it is real. Why not tell me what the mistakes are and if you're right I will try to correct them.
Q...My neighbor has an old electrical panel. Their power went out yesterday. I pulled the two bakelite blocks and found one of the cartridge fuses was bad. My question is....Should both bakelite blocks contain 50 amp fuses? Is it normal for a 100 amp service to have two bakelite blocks with two 50 amp fuses each? The reason they lost their power was that one of the 30 amp smaller cartridge fuses went bad. I replaced both 30 amp cartridge fuses with 50 amp cartridge fuses (which were the correct size for that block). Was this the right thing to do? Or should I have put two smaller 30 amp fuses back with the adapters? The 30 amp fuses were on the right side block. The left block had the 50 amp fuses already in it, if that makes any difference.
A...The fuses are there to protect the wire. Hard to tell where these go by e-mail. If this is a 60 amp fuse type panel, the cartridge fuse on the left could be the main fuses. The fuses on the right are possibly 220 dryer fuses. You SHOULD NOT replace these with higher rated fuses as the load wire for these fuses might be #10 which require fuses no higher than 30 amps and could overheat the wire with larger fuse. If you are blowing these fuses you should have the circuit checked by a licensed electrician.
Q....Greetings, I am also a Licensed Electrician. I really enjoy your site! Keep up the great work in answering the questions your readers send. Stick with your guns, and remind people that there is no price on life! Electricity can't be seen or heard to know if it's present. Our profession requires ultimate knowledge, we don't get a second chance to make a mistake! Sincerely, Jesse McKee J. J. & Z. Electric
Q....Does the small and large blade on a receptacle have a meaning? If so what?
A....If the outlet is wired correctly, the small blade slot on the receptacle should be the live wire (black) and the large blade slot the neutral. (white).
Q....What is a ufer ground?
A....The term "Ufer" grounding is named after a consultant working for the government during World War II. They needed to ground equipment in the desert and he came up with the idea of running the ground to the rebars encased in cement. The Ufer ground takes advantage of concrete’s properties to good advantage. Concrete absorbs moisture quickly and looses moisture very slowly.
The Ufer ground alone is not adequate grounding. Few buildings, even those under construction today are built to take advantage of the Ufer ground. It is common to see the use of the Ufer ground in military installations, computer rooms, and other structures with very specific grounding specifications. It is not common in most industrial plants, office buildings and homes. More common today is grounding to national and local electrical codes. This will involve one or more driven ground rods bonded to the neutral wire of the electrical service entrance.
Q....I hope this question makes sense: I would like information on "back wired quick connect terminals on duplex receptacles". I have never heard of this term, and I would like to know if quick connect terminals are dangerous or can cause fires, etc. I am working with a 110 volt, grounded duplex receptacle and the electrician I had look at it said the quick connect terminals were the cause of the receptacle catching on fire. He did not offer any other information. Please explain what he means. Thank you!
A....This type of receptacle has the stripped end of the wire placed in a pressure slot. These back wired pressure terminals can be a hazard because after being wired and pushed back into the outlet box the wire has a tendancy to become loose. Rapping the wire around the screw terminal and using pigtails for added receptacles is a safe way of wiring receptacles.
Q....Why are you so against a do it yourselfer doing electrical wiring? If they are going to do it anyway, wouldn't it be safer to show them the right way?
That's is a good point, but not good enough. The whole idea is to convince the person not to do electrical wiring. Electrical work is not like other trades. It is something you can die from. Do you really believe that an untrained person can perform electrical wiring the same as a licensed electrician with years of experience? Even if the electrician was standing there when the work was done by an unqualified person, it would still be unsafe. How do you think it would feel if I gave someone wiring advice and something happened to them or another person in the house. If you know someone who is going to jump of a bridge, would you give them advice on how to do it right?
Q... Dear Bob, First of all thanks for a really great wealth of information. It's a great comfort to have an professsional, with as much years of experience as yourself, to turn for answers. So.....now that I've "buttered you up" here's my question: What's the difference between a GFCI circuit breaker and a "regular" circuit breaker? (Like the ones, let's say, found in the breaker control panels).
A...Thanks for the kind words. A GFCI. does not measure shorts to the ground like a regular breaker, it measures the current difference between the hot and neutral wires. A sudden difference of 5 ma. or more, indicating that there is another path for the electricity to flow through will trip this device.
Q...Can a blown GFCI outlet deaden other outlets on that circuit?
A...Yes. It would affect every outlet in that circuit that is fed from the GFCI.
Q...How can you tell if a ground fault circuit interrupter receptacle is working properly?
A...The test button is not always a true test. To test the GFCI. plug a night light or any light into the GFCI receptacle. The light should be on. When you press the test button the light should go out. When you press the reset the light should go on.
Q..Where would you use the cosine of the phase angle?
A...If this is a question for a test or school paper, I would not be helping you if I gave you the answer which is. "The power-factor of any a-c circuit is equal to the true power in watts divided by the apparent power in volt-amperes which is equal to the cosine of the phase angle." If you are trying to test my electrical knowledge, than I will help you by saying that this question is way to hard for me to answer.
Q....Please! Is there anything you can tell my husband that will prevent him from fooling with electricity, before he kills himself or burns our house down?
A....Your body is a good conductor of electricity. Fortunately, your skin is a good insulator and it is not easy for current to flow through you. Unfortunately High voltages (50 volts and up)can push current so hard that it punctures your skin and begins to flow through you.
Just check out the low values of current that can cause a shock. Electric current will flow through both arms, through an arm or leg to ground, or through any body surface to ground. There is a certain current level at which an individual cannot voluntarily release from the circuit. This is the "cant let go current" from which burns and death by electrocution can result. Electrical shock begins when the current through the affected parts of the body is about 0.002 amperes. When the current increases to about 0.015 to 0.020 amperes, it becomes impossible to let go of the circuit. At higher values of current, above 0.100 amperes, heart stoppage will occur and cause almost certain death. Electrical circuits of 120V can kill just as fast as 240V, 480V, because the current flow through the body is dependent on the body’s resistance. Electrical shock can also cause quick movements which may result in other injuries.
Q....Sorry if I sound really stupid, but I know nothing about electricity. I bought an older home (46 years old) two years ago and some of the outlets are so loose that cords fall out. I want to replace them. They are two-prong, not grounded. My friends tell me I should install the three-prong outlets, even though they don't have a grounding wire inside. I think that is bad advice, since I'm afraid someone might think they are grounded. I want to hire an electrician, and a friend of mine says he'll do the work, but tells me to install a 3-prong outlet, even though they may not be grounded. That way, I wouldn't need to use an adapter for three-prong cords, such as the "strip" I use for my computer, printer, etc. Please advise me. I have called two electricians, but they are so busy, they don't return phone calls or if they do call and you miss their call, they may never call again! THANKS!
A.... You sound smart to me. You are right, very bad advice and not up to code to place a grounded receptacle in an ungrounded outlet. A surge surpressor is useless without a grounded outlet. For safety reasons you should have grounded outlets. With all due respect to your friend, you should keep trying to get an electrician. You probably wanted to hear something else, but you asked my advice.
Q....We have experienced some electrical outlets that do not work anymore. There are five of these outlets through out the house. Only the top of the outlets don't work. These outlets appear as if they were overloaded, but when I go to the panel box none of the circuit breakers had tripped. What's up with that?
A....You might want to check to see if the top part of these receptacles are on a switch somewhere. It sounds like they are on split receptacles. The top half on a switch. The bottom made direct.
Q....I have just fitted an electric shower, after 5 min use it trips the 30amp fuse in the box. help.
A....If a device trips a breaker right away it is usually a short circuit in the wiring. If the device keeps tripping the breaker every few minutes than it could indicate the circuit is overloaded. Not a good idea to keep resetting breaker. You might want to have an amperage reading taken on this circuit.
Q....Very informative site. I hope you can help me with a question. My son is selling his house. The house inspector for the buyer suggests that the central air breakers be replaced. Currently the AC is wired with one wire to a 20 amp breaker and the other wire to a separate 20 amp breaker located next to it. He suggested the two breaker setup be replaced with a single pole 30 amp breaker.
My questions and concerns are the panel has been inspected by 3 other inspectors in the past couple of years and this has never came up. Also wouldn't increasing the breaker size to 30 amps increase the probibility of danger because of increased power flow. The current wiring has been in place for many years and to our knowledge the breakers have never tripped.
A....If this is a 220 volt circuit than both breakers should be made together so if one has a fault they both trip out. The size of the breaker depends on the wire size. A 30 amp breaker has #10 wire. The circuit has the potential for a maximum of 30 (actually 26) amps. The load on the wire depends on the devices on that line.
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