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  • Afci

    I's i't just bedrooms for AFCI , or do living, and Dining need them?


    Whats the deal with bedroom lights, they need to be on the same circuit with AFCI?

    Some people say yes, others say no.....

    What about loosing light if the AFCI trips?

  • #2
    Re: Afci

    Originally posted by gotflow View Post
    I's i't just bedrooms for AFCI , or do living, and Dining need them?


    Whats the deal with bedroom lights, they need to be on the same circuit with AFCI?

    Some people say yes, others say no.....

    What about loosing light if the AFCI trips?
    Can someone explain to an interested layman why arc-fault CI's are necessary or what problem they are designed to correct?

    Comment


    • #3
      Re: Afci

      While GFCIs are intended to protect human life, the use of AFCIs are required to protect the wiring in the home. They use advanced electronic circuitry to measure "normal" and also "abnormal" arcing conditions in the wire. When you flip a switch, you often see (if you look closely) a tiny arc at the switch point. That is a normal arc situation and the AFCI would not trip. Same when you plug in your big Ridgid drill and the brushes arc as you run it. AFCI would not trip. What you, the homeowner cannot see is the arcing that often occurs in the wiring circuit itself or at the point of junctions inside a J-box. The AFCI is designed to determine line to line arcing, line to neutral arcing and line to ground arcing. If any of those conditions are determined, the AFCI trips. The arcing stops and the wiring remains "safe." Without that, however, you may get arcing, say at the point where the wire wraps around the screw terminal inside a receptacle. The constant heating and cooling of that connection will cause the connection to loosen up overtime. They will get so loose at some point, that the connection is barely there and arcing will occur. You will never ever see that or even hear it, but it is occuring. Eventually, that arcing will get the insulation so hot it will burn it off. It may heat up the wires outside the J-box and burn off insulation and start a fire either in the home's insulation, or in the framing, or any other combustible item that is nearby. I cannot tell you how many times I have gone into a J-box to either tie in to pull power or to change a receptacle or whatever, and came across wires where the insulation was burned black and destroyed to the point that the wires were exposed. These are fires just waiting to happen and they do. Fire departments will often list a home fire's cause as "electrical" and that is exactly what they are talking about. When the fire inspectors go thru a home, they can determine which box a fire started in ,and while the wiring may be obliterated, the heat signature and the amount of charing at that point tells them the fire started right there. While the introduction of AFCI's may seem like a lot of hassle, they are not and they have proven to save lives. The wiring in bedrooms (lights and outlets according to the NEC code) are required to be AFCI protected because that is where people sleep. Most other areas of the home are where people are present during waking hours, so NEC figures those areas would be more likely to have a fire discovered in them than in a bedroom.
      The arcing "problem" is also part of the reason why all electrical connections MUST be made inside of a J-box. The J-box is designed to contain the arcing or heat. That's boxes need to be covered.
      The other reason is that a J-box is easier to locate (and may not be buried in a ceiling or a wall, or in some other out of the way locale) and service that a couple of wires tied together with some wire nuts and covered up with a piece of insulation.
      Sorry for the length of this post. Hope it helps clear some things up though.
      Cheers,
      Jim Don
      PS If it doesn't, we'll try another explanation later.

      Comment


      • #4
        Re: Afci

        Originally posted by JimDon View Post
        While GFCIs are intended to protect human life, the use of AFCIs are required to protect the wiring in the home. They use advanced electronic circuitry to measure "normal" and also "abnormal" arcing conditions in the wire. When you flip a switch, you often see (if you look closely) a tiny arc at the switch point. That is a normal arc situation and the AFCI would not trip. Same when you plug in your big Ridgid drill and the brushes arc as you run it. AFCI would not trip. What you, the homeowner cannot see is the arcing that often occurs in the wiring circuit itself or at the point of junctions inside a J-box. The AFCI is designed to determine line to line arcing, line to neutral arcing and line to ground arcing. If any of those conditions are determined, the AFCI trips. The arcing stops and the wiring remains "safe." Without that, however, you may get arcing, say at the point where the wire wraps around the screw terminal inside a receptacle. The constant heating and cooling of that connection will cause the connection to loosen up overtime. They will get so loose at some point, that the connection is barely there and arcing will occur. You will never ever see that or even hear it, but it is occuring. Eventually, that arcing will get the insulation so hot it will burn it off. It may heat up the wires outside the J-box and burn off insulation and start a fire either in the home's insulation, or in the framing, or any other combustible item that is nearby. I cannot tell you how many times I have gone into a J-box to either tie in to pull power or to change a receptacle or whatever, and came across wires where the insulation was burned black and destroyed to the point that the wires were exposed. These are fires just waiting to happen and they do. Fire departments will often list a home fire's cause as "electrical" and that is exactly what they are talking about. When the fire inspectors go thru a home, they can determine which box a fire started in ,and while the wiring may be obliterated, the heat signature and the amount of charing at that point tells them the fire started right there. While the introduction of AFCI's may seem like a lot of hassle, they are not and they have proven to save lives. The wiring in bedrooms (lights and outlets according to the NEC code) are required to be AFCI protected because that is where people sleep. Most other areas of the home are where people are present during waking hours, so NEC figures those areas would be more likely to have a fire discovered in them than in a bedroom.
        The arcing "problem" is also part of the reason why all electrical connections MUST be made inside of a J-box. The J-box is designed to contain the arcing or heat. That's boxes need to be covered.
        The other reason is that a J-box is easier to locate (and may not be buried in a ceiling or a wall, or in some other out of the way locale) and service that a couple of wires tied together with some wire nuts and covered up with a piece of insulation.
        Sorry for the length of this post. Hope it helps clear some things up though.
        Cheers,
        Jim Don
        PS If it doesn't, we'll try another explanation later.
        Good explanation. I've pulled a couple of really old outlets that presented wiring with badly degraded insulation and some pitting and "scorch marks" on the plate under the screw terminals. Sounds exactly like what you are describing. (you're also making me want to pull all the old metal boxes out of my walls)

        So, if I understand correctly, an AFCI that keeps tripping is trying to tell you that it would be a good idea to check the connections on all of your outlets and any JB's on that circuit?

        Are AFCI's installed at the panel like circuit breakers? Are they installed like GFCI outlets? Both?

        Comment


        • #5
          Re: Afci

          Don't pull those metal boxes. They're the best things on the market. I hate plastic boxes and remember plastic melts. Metal doesn't.

          An AFCI that is tripping is telling you to start investigating. Something needs attention now. Start by looking inside the boxes and any other connections. People don't realize it, but switches will go bad, and the cheap receptacles will also wear out much sooner than the spec or commercial grade receptacles. Arcing there is also a possibility.


          AFCI breakers for protecting an entire circuit are installed just like a regular CB. Same for GFCI breakers. AFCI receptacles and GFCI receptacles are installed just like a regular receptacle. Read the instructions on the GFCI recepts so you understand how the downstream (load side) ones are wired in. Somebody posted recently about how a non-GFCI receptacle had tripped a GFCI. All that is telling you is they are on the same circuit and the regular receptacle is also GFCI protected, it's just wired in on the load side (correctly) of the original GFCI outlet.

          Jim

          Comment


          • #6
            Re: Afci

            Plastic may melt, but metal burns anything that touches it.

            To answer the question, the 2008 code requires damn near anything not under direct GFI protection to be AFCI protected in a dwelling.

            Also, with arc-fault breakers, they can be very sensitive, while also be very reluctant.

            Here is why. Think of AFCI's as "Voltage" circuit breakers. They monitor the sine wave of the circuit in reference to ground. When an arc-fault occures, the sin wave "spikes", a signature the breaker is designed to break the circuit under. However, as they need a ground reference, the neutral must remain separated from ground, thus it is instead placed on the breaker so the entire loop is passing through. Much like a GFCI breaker. However, any little thing that can cause an arc will trip that breaker. From a worn out switch, to even a loose bulb in a lamp socket. That breaker will sense that arc and trip out. Hence "arc-fault". Finally,
            when performing new construction, special care must be taken to ensure neutrals of different circuits are not tied together., especially in boxes with multiple circuits. Due to different currents running through those neutrals, that anomaly will too trip not one AFCI but the AFCI it's paired with. Also, a short between the neutral and grounding conductor will trip the breaker as well, since there is a difference in current between the ungrounded conductor and the neutral.

            whew!


            Now for the reluctant part. Remember when I said it uses ground as a reference to "measure" the voltage sin wave? Guess what, you need a good ground to accomplish that. Also, (For the electricians here) Remember that little FPN about voltage drops and wire sizing to compensate for that? It is even more critical now to consider , maybe running that 15 amp circuit to the bonus room above the garage that's on the other side of the house in 12-2 rather than 14-2 for two reasons: One, that voltage drop will become a grave issue now that the circuit has an inherent resistance. And two, due to having a resistance in the line, any "arc-fault" condition will get eaten up by that resistance and thus prevent that AFCI from facilitating that circuit. In other words, that arc will never reach the breaker. Which means that breaker WILL NOT TRIP! You might as well just put a copper busbar jumper feeding that romex!


            *On a side note, a voltage drop is not something electronics enjoy operating under. Make sure the wire is large enough to deliver the voltage, and handle the current load for that voltage mmmm'k?

            Comment


            • #7
              Re: AFCI

              And two, due to having a resistance in the line, any "arc-fault" condition will get eaten up by that resistance and thus prevent that AFCI from facilitating that circuit. In other words, that arc will never reach the breaker. Which means that breaker WILL NOT TRIP! You might as well just put a copper busbar jumper feeding that romex!
              So does this mean a branch circuit with a long run from the breaker panel would be better off with a AFCI receptacle which would be located closer to the point of the potential fault. But then your feed is only protected by a regular CB. Not a good idea to chain (in series) AFCIs or GFCIs I think, right?
              ---------------
              Light is faster than sound. That's why some people seem really bright until you hear them speak.
              ---------------
              “If I had my life to live over again, I'd be a plumber.” - Albert Einstein
              ---------
              "Its a table saw.... Do you know where your fingers are?"
              ---------
              sigpic http://www.helmetstohardhats.com/

              Comment


              • #8
                Re: AFCI

                Originally posted by Bob D. View Post
                So does this mean a branch circuit with a long run from the breaker panel would be better off with a AFCI receptacle which would be located closer to the point of the potential fault. But then your feed is only protected by a regular CB. Not a good idea to chain (in series) AFCIs or GFCIs I think, right?

                Sir, if you can find an AFCI receptacle, mind showing me if you please? Last I checked, while yes it is in the code book, no one manufactures it due to the sheer requirements needed to install one.

                Here is the official statement of the 2008 NEC:

                210.12 Arc-Fault Circuit-Interrupter Protection.

                B. Dwelling Units. All 120-volt, single phase, 15- and 20-ampere branch circuits supplying outlets installed in dwelling unit family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, or similar rooms or areas shall be protected by a listed arc-fault circuit interrupter, combination type, installed to provide protection of the branch circuit.

                Exception No. 1 Where RMC, IMC, EMT, or steel armored cable, Type AC, meeting the requirements of 250.118 using metal outlet and junction boxes is installed for the portion of the branch circuit between the branch-circuit overcurrent device and the first outlet, it shall be permitted to install a combination AFCI at the first outlet to provide protection for the remaining portion of the branch circuit.


                *Wow what a mouthful*

                Anyway, for "chaining" GFCI with AFCI, (For the love of GOD, do NOT take what I am about to say as any 'official' statement!) I remember one such house my employer was faced with such a question. Typically, we would take the line side of a GFCI receptacle for an appliance circuit feeding a kitchen counter, and use it to feed the dining room outlets as well. However, when 2008 came around, we questioned wether to place such a circuit onto an AFCI breaker to feed a GFCI outlet, then feed the dining room. Instead, what we did was rather than line-side the dining room from the GFCI, we placed that portion of the circuit on the load side and therefore GFCI protect the dining room outlets. Since it was under GFCI protection, we beleived it no longer needed AFCI breaker protection. It seemed it passed the AHJ muster during the inspection. However, I MUST STRESS that just because it passed one AHJ, doesn't mean the next one will pass it as well.

                To further confuse things, not every state has adopted the 2008 code, there are a few states out there that still uses the 2005 code, so like anything, to get the official statement, ask the one authorised to make such a statement.
                Last edited by tailgunner; 12-12-2009, 05:46 PM.

                Comment


                • #9
                  Re: Afci

                  Sir, if you can find an AFCI receptacle, mind showing me if you please?
                  Can't show you and I have never seen one either. I was assuming based on JimDon's post that they were out there.
                  AFCI receptacles and GFCI receptacles are installed just like a regular receptacle.
                  ---------------
                  Light is faster than sound. That's why some people seem really bright until you hear them speak.
                  ---------------
                  “If I had my life to live over again, I'd be a plumber.” - Albert Einstein
                  ---------
                  "Its a table saw.... Do you know where your fingers are?"
                  ---------
                  sigpic http://www.helmetstohardhats.com/

                  Comment

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