apostolakisl
Senior Member
I would encourage you to read the manual for the exact model you are looking at buying. These things can be different from one to another.
2 wire vs 4 wire smokes
- Thread starter Mr Spock
- Start date
I would encourage you to read the manual for the exact model you are looking at buying. These things can be different from one to another.
For System Sensor i3 series detectors (2-wire and 4-wire), you can tell if it has a built-in sounder by the model number. If the model number has an "A" in it, e.g. 2WTA-B or 4WTA-B, it has a sounder. If it doesn't have an "A" in the model number, it doesn't have a sounder. Likewise, if it has an "R" in the model number, it has the additional Form C relay in it that latches on alarm (mentioned above).
I'm new to the smoke detector stuff, too. I spoke to Automated Outlet earlier this week, and for me, they recommended the System Sensor 4WTA-B. I didn't consider the 4WTAR-B until after I talked with them, so I don't know their position on the setup I previously described using the Form C relay to indicate the detector that tripped.
Keep in mind that I have an Elk M1G instead of an HAI panel, so that may affect your decision. For example, the M1G only has one zone for 2-wire detectors, but any/all zones can be used for 4-wire. Since I have an outbuilding that I also want to put detectors in, and the outbuilding already has a zone expander card located in it, putting one or more 4-wire detectors will be easier to do since they can connect to any zone on the zone expander. 2-wire detectors would have to be wired back to my home, which wouldn't be easy to do.
apostolakisl
Senior Member
Here is the model I put in my house. http://www.surveilla...channelid=NEXTAI just have one of these at the EOL and the non-relay ones before that. As you can see, you might want to put relay ones everywhere since the unit opens the relay if there is an internal error.
It has a sounder. It consumes 51ma when the sounder is on. So, just one unit with a sounder would exceed the amps an Elk zone can put out.
It consumes 15ma in non-alarm condition, so you can see how trying to power these guys would be a challenge without a separate power source. Some of the 2-wire ones I looked at only consume micro-amps in standy mode, so that would explain how they would still function.
I pulled up some specs on 2-wire models that have sounders, but they stipulate that current is up to 70ma and would be limited by the panel. . . i.e. if your panel can't put out the current, the sounder is going to not work or be pathetic.
And I would note that zone 16 on the Elk might be capable of more amps. It is the predetermined smoke detector zone.
EDIT: I just pulled up the Elk manual. Zone 16 has a jumper for 2-wire smoke which changes the power settings.
It has a sounder. It consumes 51ma when the sounder is on. So, just one unit with a sounder would exceed the amps an Elk zone can put out.
It consumes 15ma in non-alarm condition, so you can see how trying to power these guys would be a challenge without a separate power source. Some of the 2-wire ones I looked at only consume micro-amps in standy mode, so that would explain how they would still function.
I pulled up some specs on 2-wire models that have sounders, but they stipulate that current is up to 70ma and would be limited by the panel. . . i.e. if your panel can't put out the current, the sounder is going to not work or be pathetic.
And I would note that zone 16 on the Elk might be capable of more amps. It is the predetermined smoke detector zone.
EDIT: I just pulled up the Elk manual. Zone 16 has a jumper for 2-wire smoke which changes the power settings.
Where did you see this listed?
I'd also like to thank everyone who has been contributing to this thread as I'm learning a lot and will be replacing my smokes in a few months. I'm just about at that "10 yr. replacement mark" anyhow.
apostolakisl
Senior Member
On the downloaded m1g manual page 6. It lists compatible 2-wire detectors and max number (20). Also you need to use a different eol resistor (820ohm) I assume since it will let more current through. You would need to pull up the listed approved detectors and see if any of them have sounders. It shows the jumper that you need to move powering the zone differently than a regular zone. It does not list the actual specs on the power. Maybe you could put an amp meter on it and let us know. I measured the regular zones a while back and the number 4ma comes to mind (shorted with no eol resistor), but it is possible I am remembering wrong.
Lou, in this case this post and your subsequent post is extremely incorrect and misleading. I am not flaming you, but merely trying to provide accurate information.
The case of a sounder, or multiple sounders going off is generally a non-issue with most panels,and I have not seen an issue where a panel is unable to support the proper # of smoke detectors listed in alarm state, the inherent problem is accomplishing a tandem ring with all sounders synchronized, and the problem with a reversing relay, no matter 2 or 4 wire, is you need to have it connected to a supply capable of powering all the sounders involved going off. The statement "limited by panel" with current values is misleading and easily misunderstood by those that are not in the trade/industry. I'm not going to get into the whole definitions or explain how these things are rated/engineered, as that value is irrelevant to this discussion.
A power supervision relay IS required by code for a 4 wire fire loop and the majority of manufacturer's smokes that have an aux relay listed, it is not for these purposes, so 9/10 times a separate power supervision relay is needed and installed. Your statement regarding the 4WTAR is absolutely false regarding a power supervision relay, as the aux relay is intended for a separate purpose (such as elevator recall or release). The one you listed does have a supervisiory relay, however that is a rare thing to find in any manufacturer's unit.
In the case of the Elk (and other panels) it makes no difference as to how much power the zone on a 2 wire fire circuit can put out, as the maximium # of detectors, as well as compatible detectors, is listed by the manufacturer or the panel as well as the smoke detector's manufacturer. Intending on exceeding or not heeding the manufacturer's number of supported units is foolhearted, and in the case of a reversing relay on a 2 wire fire loop, the power for the tandem ring is always drawn from another power source and not the zone in question, so current draw upon alarm is not relevant to this discussion.
Depends on the panel, however if wired to an individual zone, they all function and indicate the same, the only difference is how a reversing relay would need to be wired/attached. You could use a single one for multiple 4 wire loops, however you would need one for each 2 wire loop.
apostolakisl
Senior Member
I am not sure how you can say "extremely inaccurate" and such things as "in the case of elk it makes no difference how much power on zone 2". These things are not wrong at all. I was wrong to say that on that one model smoke the relay was supervisory, and I did own up to it. When you get into particulars on particular models you just have to read the exact specs on that model. To say that the GE model is unusual, well that seems odd, GE is a huge supplier of security and fire detection equipment. If GE is the only guys to do this, then good for them. Why would I want the clutsy situation of having a separate power supervision relay when I can have a neat and clean one built right in.
Regarding your statement on my comment about zone power, it absolutely does make a difference how much power the panel can supply on a 2-wire. This kind of has everything to do with the whats and whys of 2 wire. Everyone should read the specs and follow them, but you can also try to understand the why. This is a forum for people who might like to talk about the why's and understand things. It kills me when I pay guys to intall/fix equipment in my home or office, anything, and they don't have even the beginning of a clue as to why they are doing anything. They are like trained monkeys, "if this then that". It is always refreshing when I work with someone who I can actually talk about the whats and whys of these things.
Here is what it really comes down to, 4-wire detectors have the alarming leads set up to work the same as any alarm zone. Open trouble, closed alarm, eol resistor normal. For all intents and purposes, there is no limit to how many can go on a zone. When they alarm, they latch and need a power cycle. They should have a power supervising relay at the end of line. I covered the why on all this stuff in my first post.
2-wire units are particular. They get their operating power from the same wires that they use for alarming. This results in issues that require the units to be matched to the panel. If you want to use 2 wire units, then you get just a few choices and you need to learn the particulars of your system.
This is 90% of the security industry among other industries. There are too many "technicians" that simply know what they've done because that's how they have always done it. Ask a security tech what the yellow or blue wire is/does on a HID reader and they'll just say we don't usually use that wire. There are very few people left that actually do the research and learn their craft and can think on the fly or "outside of the box".
Sorry for the totally off topic rant but I do just enough fire to make my house safe and protected so I'll not give any fire advice today.
Lou, I'm not going to argue with you on your merits, but you're basing your knowledge and points on an item you admittedly have little to no experience with outside of theoretical applications and the generalization of how they function.
The number of detectors a panel can support as a 2 wire isn't up for interpretation or judgement, as that number is a given and also set in stone by the panel manufacturer as well as the smoke detector's manufacturer. Theoretically, any panel can support a number A times the number of B detectors that the panel can power at it's power output, however it's not a quantifiable number that is used to design an installation, so the argument is moot. A 2 wire detector is tested and listed for compatibility for the panel, and in the case of ALL panel and detector manufacturers, they provide the number and type(s) which are acceptable for use. Exceeding those listings and numbers is how systems fail and people, in the case of fire alarm, get hurt and killed.
It's not like stating I have 1 amp of aux power, how many 4 wire detectors can I power? The number is stated by Elk....20 max of the types listed. It's not a relevant item to worry about if the number of detectors installed is less than 20, and the WHY as was questioned is that allows for appropriate power and headroom for proper operation and the WHAT is the amount of power the panel is capable of putting out, which is never specified in anything but engineering spec's that I have seen. Most panel manufacturers list at least 5, and upwards of 10-20 specific detectors or series as compatible.
A 2 wire detector derives both it's power and IDC circuit from the same pair of wires while a 4 wire separates the items. A 2 wire circuit must not exceed the quantity of detectors and those used must be listed as compatible, that's it, end of story, no judgement or power calculations.
A 4 wire unit doesn't need the compatibility listing as a 2 wire, however the additional steps of an appropriate power calculation must be done, as well as appropriate methods for power supervision. Now there's judgement for power calculations, alarm standby time and maximum number which can be supported by the panel, both in standby and alarm state.
That said, 4 wire units can't also be mixed on the same circuit, IE: I have GE, System Sensor and DSC smokes on the same loop....they all function differently, and specifically, from first hand knowledge, DSC 4 wire smoke detectors will not carry the power through and function properly on the same loop as any other manufacturer's smoke detector.
In the case of a built in power supervision relay, the only manufacturer I know of that has done that is GE/Sentrol/ESL, which was the original company that engineered that specific smoke. Honeywell, Hochiki, Detection Systems (Bosch) and Gentex, which covers about 90% of the market (between all segments) do not manufacture a unit that has a built in supervisiory relay, only an aux relay which is used for the purposes I stated prior. I state this as first hand knowledge, and I'm installing upwards of 3-4000 detectors on average a year, between addressable and conventional.
The number of detectors a panel can support as a 2 wire isn't up for interpretation or judgement, as that number is a given and also set in stone by the panel manufacturer as well as the smoke detector's manufacturer. Theoretically, any panel can support a number A times the number of B detectors that the panel can power at it's power output, however it's not a quantifiable number that is used to design an installation, so the argument is moot. A 2 wire detector is tested and listed for compatibility for the panel, and in the case of ALL panel and detector manufacturers, they provide the number and type(s) which are acceptable for use. Exceeding those listings and numbers is how systems fail and people, in the case of fire alarm, get hurt and killed.
It's not like stating I have 1 amp of aux power, how many 4 wire detectors can I power? The number is stated by Elk....20 max of the types listed. It's not a relevant item to worry about if the number of detectors installed is less than 20, and the WHY as was questioned is that allows for appropriate power and headroom for proper operation and the WHAT is the amount of power the panel is capable of putting out, which is never specified in anything but engineering spec's that I have seen. Most panel manufacturers list at least 5, and upwards of 10-20 specific detectors or series as compatible.
A 2 wire detector derives both it's power and IDC circuit from the same pair of wires while a 4 wire separates the items. A 2 wire circuit must not exceed the quantity of detectors and those used must be listed as compatible, that's it, end of story, no judgement or power calculations.
A 4 wire unit doesn't need the compatibility listing as a 2 wire, however the additional steps of an appropriate power calculation must be done, as well as appropriate methods for power supervision. Now there's judgement for power calculations, alarm standby time and maximum number which can be supported by the panel, both in standby and alarm state.
That said, 4 wire units can't also be mixed on the same circuit, IE: I have GE, System Sensor and DSC smokes on the same loop....they all function differently, and specifically, from first hand knowledge, DSC 4 wire smoke detectors will not carry the power through and function properly on the same loop as any other manufacturer's smoke detector.
In the case of a built in power supervision relay, the only manufacturer I know of that has done that is GE/Sentrol/ESL, which was the original company that engineered that specific smoke. Honeywell, Hochiki, Detection Systems (Bosch) and Gentex, which covers about 90% of the market (between all segments) do not manufacture a unit that has a built in supervisiory relay, only an aux relay which is used for the purposes I stated prior. I state this as first hand knowledge, and I'm installing upwards of 3-4000 detectors on average a year, between addressable and conventional.
apostolakisl
Senior Member
Del,
No arguments on what you say above. I am not saying spec your system out by using theory. I spoke specifically to reading page 6 of the manual and quoted the 20 number and referenced the list of detectors compatible. I hooked my system per the manual, not my knowledge of the physics of electricity.
The how and why is interesting. I'd like to hear your ideas and anyone elses about these things. I'd like to measure and test. In fact, I probably will temporarily put the jumper to 2-wire and do some measuring.
I put in 4-wire. Before I did that, I chose to understand it. I installed it exactly the same as the manual. I could have just done that and quit. But I wanted to do otherwise.
Now after getting a little hooked on this thread, I'm not going to be satisfied until I have a similar grasp of 2-wire. Why. . . just because.
No arguments on what you say above. I am not saying spec your system out by using theory. I spoke specifically to reading page 6 of the manual and quoted the 20 number and referenced the list of detectors compatible. I hooked my system per the manual, not my knowledge of the physics of electricity.
The how and why is interesting. I'd like to hear your ideas and anyone elses about these things. I'd like to measure and test. In fact, I probably will temporarily put the jumper to 2-wire and do some measuring.
I put in 4-wire. Before I did that, I chose to understand it. I installed it exactly the same as the manual. I could have just done that and quit. But I wanted to do otherwise.
Now after getting a little hooked on this thread, I'm not going to be satisfied until I have a similar grasp of 2-wire. Why. . . just because.
Has anyone mentioned that fact that some 2-wire configurations (I'm thinking about the System Sensor i3 line) provide additional diagnostic/maintenance capabilities. The 2W-MOD2 module also converts the 2-wire 'network' into a generic '4-wire' interface for use with ANY panel.
