Providing AC Power to an Alarm System

Providing AC Power to an Alarm System

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In this video, Michael from Alarm Grid explains how AC power is provided to an alarm system. This represents the primary power source for a security system, and is provided from a plug-in transformer. The reason why the plug-in module is called a transformer is because it transforms the high-voltage power from the outlet into low-voltage power that won't overload or fry the alarm panel. That is why you will often hear alarm system transformers being referred to as "step-down" transformers.

A wire is connected between the plug-in transformer and the alarm panel. This wire transfers the current from the transformer to the panel. In most cases, the wire is detachable and can be removed from the transformer. This is important because it means that the entire transformer won't need to be replaced in the event that the wire becomes damaged. It also allows for an ideal length of wire to be cut for the installation job at-hand. You want the wire to be long enough to comfortably connect the panel to the transformer, but not much longer than that. Michael refers to the outer plastic portion of the wire as a shield. It is more commonly called a sheath. Unshielded wiring is usually preferred in alarm installations, though there can be exceptions to this rule.

It is important to understand that an alarm panel will only allow for a maximum wire run of a certain length based on the gauge. This is because a small amount of current is lost as electricity travels down the wire from the transformer to the panel. A sufficient amount of power must ultimately reach the panel, so if the wire is too long, then the system will not receive enough power, and an AC loss condition may occur. This can also result in issues with intermittent low battery conditions. Thicker wire retains electricity more effectively than thinner wire. By going with thicker cabling, that is, wire with a lower listed gauge also referred to as AWG, you will be able to perform a longer wire run. Check the specifications for the panel you are using to determine the maximum wire run based on the gauge and thickness of your wire. Most alarm wiring is between 18 AWG and 22 AWG.


Hi, DIYers. This is Michael from Alarm Grid. And today, I'm going to be talking about providing AC power to an alarm system. AC power represents the primary power source for an alarm system. It's basically the transformer that's plugged into the wall outlet that goes to the panel. Electrical current travels from the transformer through a wire to the panel, and it gets to the panel, and that's how the panel stays running. The reason it's called a transformer is because it transforms the high voltage current from the outlet into low voltage power to power the system. The low voltage power won't overpower the system, it won't fry it, so to speak, and it won't mess up your equipment, assuming you're using the proper transformer. You often see these referred to as step-down transformers. Because like I said, it's stepping down the high voltage down to low voltage power that won't overpower the system. So I have some props today, share Intel, to share with you. To show you a little bit about what I'm talking about here when I'm talking about a transformer and wiring and everything. So there are different types of transformers, like I said. You'll encounter AC transformers and DC transformers. The type you use depends on the specifications of the security system you're using. Some systems will need AC power and others will use DC power. Now a big difference is that when you're using an AC transformer, polarity doesn't matter. Meaning you don't have to observe which wire goes to which terminal. That is for positive and negative power. Both of the terminals will be equivalent, and you can have either wire going to either power connection on the panel. So I have one transformer here, this is an example of an AC transformer. And you see it just says, AC and AC, so I could have either copper wire going to either one and then having it go to either connection at the panel. You won't have to observe polarity. So that makes it a little bit easier, just something you don't have to worry about. But conversely, this transformer right here is the DC transformer. So if you look closely you'll see that it has a positive terminal and then a negative terminal. So positive traditionally, that's where you connect the red wire, and the negative, that's traditionally where you'll connect the black wire. Negative also sometimes referred to as the ground connection. And you'll want to observe polarity at the panel as well. When you go to connect the wires at the panel, you want to make sure that the positive, like I said, that's usually the red one, is going to something like 12V DC or you'll have a positive symbol, a plus sign. And then the negative, the black wire, it's going to ground G and D or maybe a negative symbol, a minus sign. So you have to observe polarity on the DC transformer. Now, as you can see on both of these transformers, there is no wire currently connected. The wire is detachable, and you actually have to supply your own wiring in most cases. Usually with a system, it will include a transformer, but it won't include wiring. Now, there are exceptions to this rule, sometimes it will include a wire, but traditionally, you do supply your own wiring. And this is because traditionally alarm systems are-- in the past, they've mostly been installed by professional installers and you would expect a professional installer to have wire, cabling, readily available in their work vehicle so they can go and cut whatever wire length they need for the job. Normally speaking, you want to have the wire to be enough distance to reach the outlet and the panel obviously. But you don't want it to be too much longer than that. You want it to be just long enough. You want like a little bit of slack, so that way you can complete the connections comfortably. But you don't want to have a wire that's super long. And I'll explain more about that in a little bit. And that's also just for preparation, is that way you're not having wire going all over the place or anything. But a professional installer will be able to cut the wire to the exact need that they need for the job at hand. So that's a big reason why the wires are detachable. Also just in case the wire becomes damaged or cut then you don't need to replace the entire transformer. And just as an example here, I do have a transformer that is fixed-- has a fixed wire, a permanently connected wire that can't be detached. So you see if this transformer-- if the wire on it were to become damaged, then I would likely need to replace the entire transformer. So that's pretty inconvenient. So you don't usually see those well with alarm systems. You might occasionally, but that's not as common. Now, I do want to talk a little bit about some of the wiring you might encounter with an alarm system. One thing I do want to mention is, like I said, there's a maximum wire run distance that most panels will have in their specifications. As current travels down a line, there's a loss of current along the way. A small amount of current becomes lost along the way. And it becomes more prominent as the cable becomes longer. So if the cables too long, too much current will be lost along the way and not enough current will reach the panel. You'll get an AC lost condition or the panel might not power on. So you'll want to observe the maximum wire run distance based on the panel you're using. And that also applies based on the thickness of the wire that using or the gauge, the AWG. The most common gauges for alarm system wiring, it's usually a 18-gauge or 22-gauge wire. Lower gauges, are thicker than higher gauges. So 18-gauge wire is thicker than 22-gauge wire. When you have thicker wiring, it holds currents a little bit better. So you'll be able to do a longer wire run. So if you're worried about having to do a long wire run, if you really have to stretch the distance from the panel to the transformer, to where it's being plugged in, the outlet, then you probably want to go with a thicker gauge wire. Just to show you some examples here, I do have some-- believe this is 18 gauge wire right here. And you'll see that this is solid core wiring. Now, we normally don't recommend solid core wiring. You can use it, it works just fine. It's going to accomplish the same goal as any alarm wiring. The other type that I'm going to show you today being stranded alarm wire, which is what we recommend. But you'll see that this is a little bit less flexible. I mean it is flexible, I am moving around as you can see. But it's not as forgiving. It can become cut pretty easily. It's just a solid core, it's just one solid inner wire. Some installers might prefer working with this. I personally don't. What I prefer here, is the stranded wire, which I have just a small piece cut here just to show you for example. You see that the wire is split into different strands, I can split it up. So even if one strand were to become broken, then it would still work fine. It would still be able to transmit the current down the line. So it's a little bit more forgiving. It's more flexible, it's a little bit easier to work with. And you see that this is 4-conductor wire here. So if I only needed to use two of the wires, say I just needed the red and black for power, I could just tie the green and the white wires back or I could cut them, and I would still be able to use this fine. So that's an advantage to a 4-conductor wiring there. This back here was a 2-conductor wiring. It just has the two inner wires, which is fine for providing power, but there might be some applications where you do need the four inner wires such as motion detection sensor. A hard wired motion detection sensor where data and power are being transmitted. Data being zoned status information between the panel and the sensor. So whether you use 4-conductor or 2-conductor wire, it's up to you. You can double up 2-conductor wire, by the way, if you need a four wire connection. So that's also something to keep in mind. But this is 22-gauge wires, so it won't be able to do as long of a wire run as this 18-gauge wire. This is a little bit thicker, so it can hold current a little bit better as it travels down the line. So make sure to look at the specifications for your panel to see the maximum wire distance, and it usually differs based on the gauge you're using. When you are preparing wire, you will need to have a wire stripper. We have one here. I'm not going to be demonstrating it on camera, but I do want to show it off. We have markings on the wire stripper based on the gauge that you can use to insert the inner wires. You see there's an outer shield for the wires and there's inner wires in there, and then you strip the covering off the inner wires to reveal the copper. So you would do this based on the gauge. If I were doing a 22-gauge wire, I would stick it into this hole in this be able to pry right off and reveal the copper. You see that I already did this in the wire that we have here today I already prepared it, but you see on this end it's not repaired yet. I would have to remove the outer wider area to reveal the four inner wires and then strip them one by one. So that's something I would do when preparing wire. But there is an alternative to having to prepare wire. We have what's called a Honeywell LT-Cable, and this is an already prepared wire, I didn't do anything to this. It comes in two parts, there is a small part right here, and then there's a larger part, which we have tied up to make it easier for me to hold. But you see the larger end ends in spade connectors, that can easily connect at the transformer. So you would make these connections using a screwdriver. And then it goes down to the male barrel connector on the other end and plugs into the female barrel connector like that. And then at the other end, you have some ports that you can easily plug into the panel, that will easily go in. You will see some panels that have a barrel connector that you can use to just-- you won't have to use the small portion of the wire. You can just use the large portion of the wire and that entails connecting at the transformer and then this part goes into the barrel connector at panel, the female barrel connector. And I believe that this is a positive ending connection. So you have to make sure your panel supports it, if it does have that barrel connector. So check those specifications to make sure that's the case. It's a positive center connection, something like that. So just make sure you look into that And most cases any panel that's going to support a barrel connector-- not all panels will have that. An example of a panel that does the 2GIG GC3e, actually does. And it will be fine, but you do want to check the specifications to make sure you don't reverse polarity. So make sure to look into that. So that's pretty much providing AC power to a panel. And most panels will come with a transformer, but you will need to supply your own wire in most cases. There are exceptions. The QOLSYS IQ Panel 2 Plus, comes with a prepared wire for you to use and all you need to use to set it up is a screwdriver. So it really varies depending on the wire-- I mean depending on the panel that is. Just make sure that you observe the maximum wire distance. Remember that thicker wire, a lower gauge, will be able to allow for a longer wire run. So that's something to keep in mind if that's an issue for you. The Honeywell LT-Cable, I didn't mention this, it's only 8 feet long. So if you need something longer, then you might consider preparing your own wire. While this is convenient, it's not necessarily the longest wire out there. So you need to keep that in mind. And remember we do recommend stranded wire over solid core wire. Both will work fine if you happen to have solid core wire on hand, you don't necessarily feel like you need to go out and get new stranded wire. But if you are wiring off, then that might be a worthwhile investment. Just because it's easier to work with, and it's a little bit more forgiving. Like I said, even if just one of these-- like if one strand comes off, like, if I were to just take that guy right there on this white wire, and it wasn't properly connected, then the other wires would still be there to pick up the slack and do the job. So that's what you need to know about providing AC power to a panel. It's a transformer, it's a step-down transformer that turns high voltage power into low voltage power that is suitable for an alarm system. So if we have any questions about providing power to an alarm system or you want to learn more about alarm monitoring service or you have questions about a specific alarm system, send an email to If you found this video helpful, make sure to give it a thumbs up below to like the video, and remember to subscribe to our channel for updates on future videos. We hope you enjoyed the video. Thank you.