I am using 10awg 2 conductor wiring with an audio amplifier that has a rated power output of 2500 watts and a 4 ohm speaker that is rated at 2500 watts of input. What class wiring is this? Also I am using 18awg 2 conductor wiring with an audio amplifier that has a rated power output of 1000 watts @ 70 volts to a load of sixteen 60 watt 70 volt speakers paralleled. What wiring is this? Is class 2 or class 3 speaker wiring required to be in conduit? If the 10awg wire is an unlisted type can I put it in conduit to comply? In a permanent installation, if I used 12awg 4 conductor SOW wire for speaker wire for applications that have class 1 requirements, must I put it in conduit?
speaker wiring- class 1 or 3
- Thread starter djmrts
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hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: speaker wiring- class 1 or 3
I belive that the listing info on or with the amplifier will tell you class 1 but look for it on the back of the amp or in the paper work that came with the amp. Most comercial amps are class 1 rated. But heres the kicker nobody make a class 1 speaker cable! I mean nobody. I have looked for this before and even wrote beldin cable with no results.
I belive that the listing info on or with the amplifier will tell you class 1 but look for it on the back of the amp or in the paper work that came with the amp. Most comercial amps are class 1 rated. But heres the kicker nobody make a class 1 speaker cable! I mean nobody. I have looked for this before and even wrote beldin cable with no results.
hbiss
EC, Westchester, New York NEC: 2014
- Location
- Hawthorne, New York NEC: 2014
- Occupation
- EC
Re: speaker wiring- class 1 or 3
The answer has nothing to do with the output wattages, voltage, speaker impedances or most else you listed. The answer to what wiring method to use is listed (or should be) on the rear of the amplifier next to the outputs. It will say Class 1, 2 or 3 wiring may be used. See Article 640.9(C).
Baring any local restrictions, CL3 and CL2 does not have to be run in conduit regardless of the fact that it is a 70.7 volt output. See 725.25.
Class 1 is a whole 'nuther can of worms. Class 1 wiring must comply with NEC Chapter 3 just like normal branch circuit wiring. Wiring has to be listed and no, you can't run SOW cord in conduit.
This is a can of worms because you are pretty much stuck with conduit and TFFN or THHN conductors (725.27(B)) since nobody makes a suitable Class 1 audio wiring product. We have TFFN twisted into a pair and pull it in conduit.
Another problem is that since this must comply with Chapter 3 you need equipment grounds and appropriate methods to connect to speakers such as standard sized knock outs and enclosed terminals or at least listed connectors. (Don't know if Speakons are listed). Unfortunately many speaker manufacturers do not make a Class 1 compliant product.
Take heart though because most inspectors will be as much in the dark about this as you were.
The answer has nothing to do with the output wattages, voltage, speaker impedances or most else you listed. The answer to what wiring method to use is listed (or should be) on the rear of the amplifier next to the outputs. It will say Class 1, 2 or 3 wiring may be used. See Article 640.9(C).
Baring any local restrictions, CL3 and CL2 does not have to be run in conduit regardless of the fact that it is a 70.7 volt output. See 725.25.
Class 1 is a whole 'nuther can of worms. Class 1 wiring must comply with NEC Chapter 3 just like normal branch circuit wiring. Wiring has to be listed and no, you can't run SOW cord in conduit.
This is a can of worms because you are pretty much stuck with conduit and TFFN or THHN conductors (725.27(B)) since nobody makes a suitable Class 1 audio wiring product. We have TFFN twisted into a pair and pull it in conduit.
Another problem is that since this must comply with Chapter 3 you need equipment grounds and appropriate methods to connect to speakers such as standard sized knock outs and enclosed terminals or at least listed connectors. (Don't know if Speakons are listed). Unfortunately many speaker manufacturers do not make a Class 1 compliant product.
Take heart though because most inspectors will be as much in the dark about this as you were.
hbiss
EC, Westchester, New York NEC: 2014
- Location
- Hawthorne, New York NEC: 2014
- Occupation
- EC
Re: speaker wiring- class 1 or 3
Hurk, if you want to split something like 100,000 feet let me know.
Since this would be MC a problem then is what to do with the green ground at the speakers. All that I have used that have wiring compartments have no ground screw nor can one be fitted. That's why EMT and a greenfield "whip" work out well.
Incidentally, there is no ryhme or reason to the wiring method required by the amplifier. I've seen 400 watt amps require Class 1 and 600 watt amps require CL2. It's NEVER listed in the amp specs or literature. Only way I've found it (other than actually looking at one) is to look at a photo of the back panel if the literature or web site provides one. It's a conspiracy. I recently saw a photo of a new QSC amp and it said NOTHING about wiring requirements on the back and it was UL listed. Think they photoshopped it out? :roll:
Hurk, if you want to split something like 100,000 feet let me know.
Since this would be MC a problem then is what to do with the green ground at the speakers. All that I have used that have wiring compartments have no ground screw nor can one be fitted. That's why EMT and a greenfield "whip" work out well.
Incidentally, there is no ryhme or reason to the wiring method required by the amplifier. I've seen 400 watt amps require Class 1 and 600 watt amps require CL2. It's NEVER listed in the amp specs or literature. Only way I've found it (other than actually looking at one) is to look at a photo of the back panel if the literature or web site provides one. It's a conspiracy.
I recently saw a photo of a new QSC amp and it said NOTHING about wiring requirements on the back and it was UL listed. Think they photoshopped it out? :roll:
- Location
- Massachusetts
Re: speaker wiring- class 1 or 3
I do not work with PAs too much but the ones I have done where not class 1.
The ones that are class 1, are the speaker terminals on the back enclosed?
What I am getting at is if they are UL listed and the speaker terminals on the back are out in the open, wouldn't that mean these are class 2 or 3?
I do not work with PAs too much but the ones I have done where not class 1.
The ones that are class 1, are the speaker terminals on the back enclosed?
What I am getting at is if they are UL listed and the speaker terminals on the back are out in the open, wouldn't that mean these are class 2 or 3?
hbiss
EC, Westchester, New York NEC: 2014
- Location
- Hawthorne, New York NEC: 2014
- Occupation
- EC
Re: speaker wiring- class 1 or 3
Bob, kind of. There is really no Class 1 listing for these things so you are really on your own. Some manufacturers like JBL and others make ceiling speakers with a standard size KO and wiring compartment that is enclosed. Only problem is that there is no means to connect an equipment grounding conductor if you used one. These are a totally enclosed metal can and are "cut in" the ceiling. They are UL listed for use in air handling spaces (Article 300.22(C)). They are also listed (UL 1480) for use with fire protective signaling systems. That's it.
These speakers are becoming extremely popular and many manufacturers are making similar products. Not all will accept standard fittings though and there is really no way to tell which will other than by looking.
For ceilings you can also use back cans with regular speakers and baffels although the above type sound alot better. The cans have standard size KO's and can be used with Class 1 wiring methods.
When you get into other than ceiling speakers the issue gets even more cloudy. Here again I've found that some JBL products have enclosed terminals (barrier strip) with a compression connector for cable entrance to the wiring compartment. Other of their products, as well as most other manufacturers, use those crummy push clips that are not enclosed at all.
With little cooperation from manufacturers and vague direction from the NEC it isn't surprising that there is little compliance in this area.
Bob, kind of. There is really no Class 1 listing for these things so you are really on your own. Some manufacturers like JBL and others make ceiling speakers with a standard size KO and wiring compartment that is enclosed. Only problem is that there is no means to connect an equipment grounding conductor if you used one. These are a totally enclosed metal can and are "cut in" the ceiling. They are UL listed for use in air handling spaces (Article 300.22(C)). They are also listed (UL 1480) for use with fire protective signaling systems. That's it.
These speakers are becoming extremely popular and many manufacturers are making similar products. Not all will accept standard fittings though and there is really no way to tell which will other than by looking.
For ceilings you can also use back cans with regular speakers and baffels although the above type sound alot better. The cans have standard size KO's and can be used with Class 1 wiring methods.
When you get into other than ceiling speakers the issue gets even more cloudy. Here again I've found that some JBL products have enclosed terminals (barrier strip) with a compression connector for cable entrance to the wiring compartment. Other of their products, as well as most other manufacturers, use those crummy push clips that are not enclosed at all.
With little cooperation from manufacturers and vague direction from the NEC it isn't surprising that there is little compliance in this area.
- Location
- Massachusetts
Re: speaker wiring- class 1 or 3
Thanks very much hbiss for all the info., it does sound difficult to comply.
We use back boxes on most all ceiling mount speakers that have a 1/2" KO and use a plastic NM connector to enter and exit usually a 16/2 or 18/2 twisted pair cable.
This would be for 70 volt systems, retail, office PAs.
I have never seen anyone put it in pipe.
I thought we did it well because we properly support the cable, as opposed to thrown across the ceiling.
Thanks very much hbiss for all the info., it does sound difficult to comply.
We use back boxes on most all ceiling mount speakers that have a 1/2" KO and use a plastic NM connector to enter and exit usually a 16/2 or 18/2 twisted pair cable.
This would be for 70 volt systems, retail, office PAs.
I have never seen anyone put it in pipe.
I thought we did it well because we properly support the cable, as opposed to thrown across the ceiling.
hbiss
EC, Westchester, New York NEC: 2014
- Location
- Hawthorne, New York NEC: 2014
- Occupation
- EC
Re: speaker wiring- class 1 or 3
For CL2 and CL3 thats fine.
For CL2 and CL3 thats fine.
ty
Senior Member
- Location
- 3rd Rock from the Sun
Re: speaker wiring- class 1 or 3
I'm curious to the 1st amp that you are using. Surely this is 2500wtts bi-amped. he cost of a 2500watt stereo unit would break the bank!
And if it is biamped, are you sure it is 2500w @4ohm output and not 8ohm. It's possible, I'm just curious.
And why 10ga. speaker wire? Is this a long run?
Or did you use ohms law to come up with this size?
I= sq.rt. of P/R
I= sq.rt. of 2500/4
I= sq.rt. of 625
I= 25
Do we need to size this wire in this way for this load??
I'm curious to the 1st amp that you are using. Surely this is 2500wtts bi-amped. he cost of a 2500watt stereo unit would break the bank!
And if it is biamped, are you sure it is 2500w @4ohm output and not 8ohm. It's possible, I'm just curious.
And why 10ga. speaker wire? Is this a long run?
Or did you use ohms law to come up with this size?
I= sq.rt. of P/R
I= sq.rt. of 2500/4
I= sq.rt. of 625
I= 25
Do we need to size this wire in this way for this load??
hbiss
EC, Westchester, New York NEC: 2014
- Location
- Hawthorne, New York NEC: 2014
- Occupation
- EC
Re: speaker wiring- class 1 or 3
I can't speak for djmrts, but I'm sure the amp is a 2 channel operated in bridged mono mode. (inputs driven from same source and outputs tied together). Several manufacturers have amps that can deliver 2500 watts into a 4 ohm load and somewhat less into 8 ohms. This is typical for solid state amps.
As for the wiring, at low impedances like this because of the high current, minimum voltage drop is the primary factor in choosing a wire size otherwise you just waste power due to line loss. I would agree though that for Class 1 wiring the minimum wire size should be per Article 310 and then increased as necessary to minimize voltage drop.
I can't speak for djmrts, but I'm sure the amp is a 2 channel operated in bridged mono mode. (inputs driven from same source and outputs tied together). Several manufacturers have amps that can deliver 2500 watts into a 4 ohm load and somewhat less into 8 ohms. This is typical for solid state amps.
As for the wiring, at low impedances like this because of the high current, minimum voltage drop is the primary factor in choosing a wire size otherwise you just waste power due to line loss. I would agree though that for Class 1 wiring the minimum wire size should be per Article 310 and then increased as necessary to minimize voltage drop.
Re: speaker wiring- class 1 or 3
The amplifier I'm using is rated 2500 watts per channel into 4 ohms and retails for over $4000. ea. This sound system is well over 1/4 million in cost! My speaker wire runs are about 50ft and I use 10 guage wire for three reasons: less loss, less resistance, and to preserve the damping factor of this or any amplifier. I looked up TFFN wire with a few manufactures and I only came up with 16awg and 18 guage wire. To further complicate things NEC says that you cannot combine class 1 wiring with class 2 and 3 with out a partition. Well, one of the speakers I'm using is a four way speaker requiring four circuits (8 wires): Sub, low, mid, & hi. The amplifier(s) that power the Sub and the low require class one wiring. The amplifier(s) powering the lower powered mid and hi require class 2 wiring. JBL provides one Neutrik NL8 receptical for an input. So what do you do?
This really sucks considering that probably 99% of all high powered dance club installations in the nation uses non-rated speaker wire or SOW without conduit. I beleive that the NEC needs to ease up and re-evaluate the audio industry on what is class 1? or some wire manufacture needs to "invent" a class 1 10awg and 12awg speaker wire that is contractor friendly.
The amplifier I'm using is rated 2500 watts per channel into 4 ohms and retails for over $4000. ea. This sound system is well over 1/4 million in cost! My speaker wire runs are about 50ft and I use 10 guage wire for three reasons: less loss, less resistance, and to preserve the damping factor of this or any amplifier. I looked up TFFN wire with a few manufactures and I only came up with 16awg and 18 guage wire. To further complicate things NEC says that you cannot combine class 1 wiring with class 2 and 3 with out a partition. Well, one of the speakers I'm using is a four way speaker requiring four circuits (8 wires): Sub, low, mid, & hi. The amplifier(s) that power the Sub and the low require class one wiring. The amplifier(s) powering the lower powered mid and hi require class 2 wiring. JBL provides one Neutrik NL8 receptical for an input. So what do you do?
This really sucks considering that probably 99% of all high powered dance club installations in the nation uses non-rated speaker wire or SOW without conduit. I beleive that the NEC needs to ease up and re-evaluate the audio industry on what is class 1? or some wire manufacture needs to "invent" a class 1 10awg and 12awg speaker wire that is contractor friendly.
hbiss
EC, Westchester, New York NEC: 2014
- Location
- Hawthorne, New York NEC: 2014
- Occupation
- EC
Re: speaker wiring- class 1 or 3
I looked up TFFN wire with a few manufactures and I only came up with 16awg and 18 guage wire.
That's because TFFN only comes in 18 and 16. If you want larger there is THHN. Note that these should be twisted per channel and have to be run in the proper size raceway or conduit from the rack.
To further complicate things NEC says that you cannot combine class 1 wiring with class 2 and 3 with out a partition.
As long as all wiring is THHN or TFFN you can put all runs in the same conduit.
As for the connector issue, you can end the conduit run near the speaker cabinet with a J box. You can then run your SOW cord from the box to the connector. You will need to use a suitable strain relief for the SOW cord where it enters the J box.
This really sucks considering that probably 99% of all high powered dance club installations in the nation uses non-rated speaker wire or SOW without conduit. I beleive that the NEC needs to ease up and re-evaluate the audio industry on what is class 1? or some wire manufacture needs to "invent" a class 1 10awg and 12awg speaker wire that is contractor friendly.
Well, it's late and I won't give you all the NEC references that apply because there are many. In all fairness you need to become familiar with the NEC so that you can see how to do these installations as compliant as possible. What you are doing is done all the time in cinemas and clubs and it can be done without running SOW cord all over the place.
The big problem here as I see it is that these are two separate industries- sound and electrical. Neither knows much about the other and the sound guys resent being told by the NEC and electrical industry how to do their work or that part of it must be installed by a licensed electrical contractor. (Witness Div 17) It seems like the sound industry couldn't care less if anything complies with the NEC so there is little impetus on their part to have complient products.
I agree that the NEC has to come up to speed on this issue but I also believe that the sound industry needs to recognize that the NEC is there to protect lives. I'm not saying that you have to become an electrician but you need to know the code articles that relate to your work and know what electrical materials are available and how to install them.
I looked up TFFN wire with a few manufactures and I only came up with 16awg and 18 guage wire.
That's because TFFN only comes in 18 and 16. If you want larger there is THHN. Note that these should be twisted per channel and have to be run in the proper size raceway or conduit from the rack.
To further complicate things NEC says that you cannot combine class 1 wiring with class 2 and 3 with out a partition.
As long as all wiring is THHN or TFFN you can put all runs in the same conduit.
As for the connector issue, you can end the conduit run near the speaker cabinet with a J box. You can then run your SOW cord from the box to the connector. You will need to use a suitable strain relief for the SOW cord where it enters the J box.
This really sucks considering that probably 99% of all high powered dance club installations in the nation uses non-rated speaker wire or SOW without conduit. I beleive that the NEC needs to ease up and re-evaluate the audio industry on what is class 1? or some wire manufacture needs to "invent" a class 1 10awg and 12awg speaker wire that is contractor friendly.
Well, it's late and I won't give you all the NEC references that apply because there are many. In all fairness you need to become familiar with the NEC so that you can see how to do these installations as compliant as possible. What you are doing is done all the time in cinemas and clubs and it can be done without running SOW cord all over the place.
The big problem here as I see it is that these are two separate industries- sound and electrical. Neither knows much about the other and the sound guys resent being told by the NEC and electrical industry how to do their work or that part of it must be installed by a licensed electrical contractor. (Witness Div 17) It seems like the sound industry couldn't care less if anything complies with the NEC so there is little impetus on their part to have complient products.
I agree that the NEC has to come up to speed on this issue but I also believe that the sound industry needs to recognize that the NEC is there to protect lives. I'm not saying that you have to become an electrician but you need to know the code articles that relate to your work and know what electrical materials are available and how to install them.
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