"Robert L Bass" a écrit dans le message de news: TpidnZUhQYbeZ6fenZ2dnUVZ snipped-for-privacy@comcast.com...
that's your opinion and it is not what I see in the field...
look like your opinion is based on a limited amount of real life experience on professionally installed system..
That depends on just how strongly they desire to wish you well. All kidding aside, I was thinking more of the situation where you hear a noise at night, arm yourself and then accidentally shoot a member of your own family.
You or a member of your household, right?
I'll grant you that. :^)
Alarm manufacturers.
I'm sure you're right about that.
People like me? I don't believe we've met. I seriously doubt you've any idea how much I know, let alone how I deal with manufacturers.
That's how almost everyone does it now. It wasn't always so.
You've only been in the alarm industry a fraction of the time I have and you've not likely dealt with anywhere near the range of products I have. Feel free to use rudeness as a substitute for reason when the latter fails you.
The above is proof that you have a difficult time constructing a sentence.
It has become quite evident that your "field" experience is rather limited.
It appears you need to take a remedial English course as well as alarm installation training.
The EOLR is not intended to detect an open window or door. It is intended to detect a short on the loop. That is the purpose. Whether you decide to use it or not is your decision. Most techs either don't use them on burg loops at all or place them in the panel where they serve no useful purpose. For the sake of clarity, I'm not saying that you ought to use them or that you shouldn't. I'm only saying what they are supposed to do and that most folks don't do it. There's no judgment involved. It's the decision of the technician or DIYer whether to use them.
The purpose is to supervise the integrity of the circuit, not the sensors themselves. I leave the choice of whether to use them to the discretion of the person doing the job.
I enjoy this newsgroup. When I ask a question, there is always a lively discussion which results in many people stepping up to the plate with opinions and answers. My question is always answered. I enjoy the humor, the flames, the OT jokes, and occasionally I'll even stir the pot myself. After my alarm system is up and running, I know I'll be addicted to coming back here every night.
Bob
I think this is what I said in my first post, namely that electronic components are listed by the manufacturers according to the state they are in with no external influence. I surmised that once the component was used in an alarm system, then the terminology went from manufacturer language to alarm language which describes the circuit, not the component parts. The various posts here appear to have confirmed my thoughts on this. As far as I know, electronics catalogs have always described a n.o. relay as the state of the contacts with no voltage applied. Even in my old Ademco, a replacement relay was sold that way without regard to its eventual function in the circuit.
Bob
You are quite wrong, friend.
Following is a link to a Sentrol product information bulletin on the 1275 series magnetic contacts. Sentrol is the most popular manufacturer of magnetic contacts in the USA. Perhaps you have heard of them. The 1275 is intended for NC loops. It opens the circuit when the magnet moves away from the switch. In the table on the second page you will find the electrical configuration of this popular switch. It is labeled as "N.O." which refers to the state of the switch without the influence of the magnet -- in other words, when the door is open. This is precisely the opposite of your erroneous statement.
http://207.173.33.114/products/pdf/1275PIB.pdf Following is a link to the document describing the 1125, a 3/8" diameter, stubby contact which is also extremely popular. You'll notice that the designation is, once again, "N.O." which describes the sensor state with no magnet around.
http://207.173.33.114/products/pdf/1125PIB.pdf GRI is another popular manufacturer of magnetic contacts. Following is a link to a product document describing their 2020 series switches. The
2020-12 is intended for use in a closed loop. It opens when the magnet moves away. GRI describes the electrical configuration of the sensor as "N.O."
You got it right. The one who was confused is one of the "professional" installers who posts as "petem".
Well, sort of. Magnetic sensor manufacturers usually do describe the sensor as N.O. or N.C. based on the state of the sensor with no maget around. Control panel manufacturers usually refer to the panel zones (sensing circuits) based on the nature of the circuit. Thus a Normally Open magnetic contact would be used in a Normally Closed loop.
That's correct. Also, some manufacturers, such as Ademco, describe their magnetic contacts as "Form 'A'" or "Form 'C'". Form "A" means there's a common lead and a N.O. lead. When the magnet moves away the circuit opens. Form "C" is another way of saying "SPDC". There's a Common, a Normally Open and a Normally Closed lead. These can be wired for "cross and break" or used in either type of circuit.
Pot, Kettle, Black!!!
Thats not exactly the situation I presented. I should have added the word IF...what trouble are you going to detect IF a window/door is opened in a loop with multiple switches and the EOLR at the proper position (in a closed loop alarm circuit - switch opens in alarm) . My point is you're not supervising too much in this case.
| Bass Home Electronics | 2291 Pine View Circle | Sarasota · Florida · 34231 | 941-925-9747 Sales & Tech Support |
| | |
It's dumb and confusing.
And to confuse a newbie even more...a powered device like a pir or gb are logically labeled...you'd connect the the NC and Com terminals for the relay on a closed loop zone.
I went through this switch terminology confustation with an electrical engineer friend of mine I''m helping to install a system in his house. I had to let him program the zone on a NO switch his way first which of course worked backwards.
| Bass Home Electronics | 2291 Pine View Circle | Sarasota · Florida · 34231 | 941-925-9747 Sales & Tech Support |
| | |
I agree. I put the resistors in the can. I think the chances of a shorted cable are remote to nonexistent. More likely failure will be a switch that doesn't open or doesn't close. Component failure far exceeds wiring failure in most electronic systems.
Bob
I'm not necessarily advocating that either.
| I agree. I put the resistors in the can. I think the chances of a | shorted cable are remote to nonexistent. More likely failure will be a | switch that doesn't open or doesn't close. Component failure far exceeds | wiring failure in most electronic systems. | | Bob | |
exactly you're not gonna see a trouble for part of the loop until the switch is closed. IMO if you really want to supervise the loop it should be with open circuit switches with eolr where it belongs... but what tech would ever want to troubleshoot that loop?
| Bass Home Electronics | 2291 Pine View Circle | Sarasota · Florida · 34231 | 941-925-9747 Sales & Tech Support |
| |
I think I understand what you're saying. Correct me if not. Let's examine what will happen in that situation. The EOLR is at the last device in a multi-door loop. The alarm is disarmed and a door is open somewhere other than at the end of the loop. Next the wire is shorted across the EOLR.
In that scenario, the zone will still show open until the customer closes the open door. At that time it will either continue to "show zone" open or it will display "zone trouble", depending on the system and the way it's programmed. Either way, the client will be unable to arm until he remedies the situation or manually bypasses the zone.
If the same series of events were to occur without the EOLR the system would initially show "zone open" until the door was closed. However, there would be no indication that the sensors downstream from the short have a problem.
That is the only difference with a properly located EOLR. How likely is it that this situation will develop in a given residential aplication? I have no idea. The only thing that you can be sure of is that with the EOLR there would be at least a slightly better level of protection. Whether that extra protection will ever make a difference on any specific installation is anybody's guess.
I think it's logical ... yet confusing.
Yep. Powered sensors almost invariably define their electrical characteristics as "normal" when the device has power and is not triggered.
An alarm system is only a part of overall security. I replaced the wooden doors that had 6 windows and put up metal doors with no windows, put in heavy duty dead bolt locks, trimmed away shrubs and trees, had the power company put security lighting on the utility pole and put in floodlights. Yes, a person could try to cover every little thing, cross the T's and dot the I's. I could hire armed guards, put up an 8 foot high chain link fence topped with razor wire and get rabid junk yard dogs, but everything must be put in perspective. Risk vs cost. Work vs protection. You can't keep a determined thief out. That's why I keep ol' Betsy under the bed, loaded and ready to go. And don't worry about my wife, she's a better shot than I am.
Bob
You're correct about component failure vs. wiring failure. Wires rarely fail once they're correctly run. However, rarely is not the same as never. It's up to you to decide how much protection is appropriate to your project. I don't fault you for the choice you made. I've only tried to explain what the options are and how they function.
The situation is analogous to the question of wiring all accessible windows. Some say you have to. Some say it doesn't matter. I say that wiring the windows affords more protection but costs more time and a few dollars extra. Only you can decide whether your home needs the extra protection.
Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.