Just curious what everyone's thoughts are on access control locks being 12v vs 24v? With pretty much every lock being dual voltage these days it seems like it would be easier/cheaper to 12vdc for everything and not worry about someone accidentally landing 12v somewhere. I know there are voltage drop issues for larger runs but lets ignore that for this.
Subscriber Discussion
Do You Power Locks With 12vdc Or 24vdc?
SD
Shannon Davis
Dec 04, 2018You can get more amperage out of 24VDC. A lock that is 12VDC and runs at .5 amps compared to a lock at 24VDC that runs at .25 amps. So it is cheaper to run a power supply and hardware at 24VDC. It takes less energy to do so.
JH
Jay Hobdy
Dec 04, 2018I don't think it takes less energy to run at 24VDC.Volts x current = wattage
24 x .25 = 6
12 x .5 = 6
Wattage is what the utility company measures and bills you by
SD
Shannon Davis
Dec 04, 2018I miss typed on that. Was trying to say you can get a lot more out of your power supply if you are running 24VDC than 12VDC.
U
Undisclosed #2
Dec 04, 2018Was trying to say you can get a lot more out of your power supply if you are running 24VDC than 12VDC.
What do you mean by “more”?
As Jay says they can (depending on the load) provide the same amount of power.
One thing that is better, as the OP notes, is line-loss is considerably less with 24v.
Another thing to consider is that there is no free lunch; electronics typically run at 5v levels or less, so the higher voltage you come in at, 120,48,24,12, the device still has to down convert the rest of the way (except perhaps for some purely electromechanical devices like electric strikes/mag locks etc.)
CK
Carl Kristoffersen
Dec 06, 2018One thing that is better, as the OP notes, is line-loss is considerably less with 24v.
The difference between 12vdc and 24vdc on 18 gauge over 200' is only about 1%. For longer runs, AC voltage travels more efficiently.
And that's how Tesla bested Edison. :-)
U
Undisclosed #3
Dec 04, 2018For fun, let's take a 12 volt and 24 volt power supply and run them side by side. Instead of applying any electrical load, apply time; say 12 hours. Which is cheaper to run for that amount of time?
Consider this test in two different ways. In the first test both power supplies are powered by an AC source and in the second test both power supplies are powered by a DC source such as a solar array. Which is cheaper to run over that amount of time?
In the end you may find out the mentioned "easier/cheaper" comparison is determined by the efficiency of the devices you are operating over time.
JH
Jay Hobdy
Dec 04, 2018Watts is watts, both are going to cost exactly the same to run over a given period of time.
There is no free electric.
There may be certain efficiencies with running a higher voltage/lower amperage over a certain length of wire but we are talking very very minimal.
SD
Shannon Davis
Dec 04, 2018Where I am coming from is if you are going to run your locks at 12VDC instead of 24VDC then depending on the size of the system you will need more 12VDC power supplies than 24VDC power supplies. We have moved our basic 8 door panel to one 24VDC power supply to run 4 control boards and at a minimum 8 locks. Sometimes more due to double doors thus more locks. If you only need one power supply instead of two this would be cheaper to run. Will you save on electricity, no, but that's not what I was trying to say.
U
Undisclosed #2
Dec 05, 2018...you will need more 12VDC power supplies than 24VDC power supplies...
But why do you say that?
This seco-alarm ps is field selectable to output either 12v@5A or 24v@2.5A. 60VA symmetrically invariant power.
Daniel S-T
Dec 06, 2018I've dealt with some Altronix Supplies in the past that had the same total amperage, but select-able voltage. So in that case, it would be better to use 24v, and get more out of that one Power Supply.
With your example of the Seco-larm, your only benefit for 24v would be less voltage drop.
U
Undisclosed #3
Dec 04, 2018Watts = Volts x Amps not watts. None of these can exist or be measured without a dimension of time.
Who knows, in a few more years we can all change if the math changes.
I prefer the 24 volt system for electronic hardware, until a more efficient lock is developed. I will leave the 12 volt systems for my 1957 VW Beetle.
Gespräch! Geschlossen!
U
Undisclosed #4
Dec 04, 2018I imagine 24 is pretty well the standard. You'll likely find most existing infrastructure using 24 both domestically and abroad. You won't see many locks/mags operating on 12 Volts in the commercial/government worlds (I don't think I'd ever seen one) as many devices like crash bar solenoids, some mags, door openers/closers/holds etc can't operate on 12.
If this is something you are actively considering, I would use (and recommend you to use) 24.
Also, don't discredit the power drop issue. We (if possible) up the conductor size to 12 AWG on any high-draw solenoid (Von Duprin etc) over 100 feet. When doors aren't set properly, hasps aren't set right etc, you need every Joule you can spare in my experience.
U
Undisclosed #2
Dec 05, 2018
Brian Rhodes
Dec 05, 2018U
Undisclosed #2
Dec 06, 2018RP
Rick Pfitzner
Dec 06, 2018In Australia, all Access Control systems use 12 VDC. I've not had an issue with voltage drop over longer distances but we normally limit the maximum runs to 100 metres from a controller. It becomes cheaper to install a LAN to another controller for runs over 200 metres.
Brian Rhodes
Dec 06, 2018U
Undisclosed #5
Dec 06, 2018Despite not being based in Australia, I can answer this -- no. I have specified and used 24vdc for locks in Australia previously, although it admittedly took some cajoling to make it happen.
RP
Rick Pfitzner
Dec 07, 2018All of the Access Control manufacturers who supply to the Australian market specify 12VDC for locks.
The various manufacturers of Electric strikes and Magnetic locks all specify 12VDC. For example the Assa Abloy Lockwood Padde electric strike has the following specification:
Voltage
12Vdc
Current
175 mA @ 12Vdc
Solenoids
Solenoids are rated for continuous use
Monitoring
Solenoid Monitor - 1 amp NO/NC microswitch
Door/Latch Monitor - 1 amp NO/NC microswitch
Holding Force
850kg Static Strength Rating
U
Undisclosed #2
Dec 07, 2018All of the Access Control manufacturers who supply to the Australian market specify 12VDC for locks.
The various manufacturers of Electric strikes and Magnetic locks all specify 12VDC.
Yet many products are 24vdc as well, for example this other Assa Abloy Lockwood Padde electric strike, the ES200:
RP
Rick Pfitzner
Dec 09, 2018I Agree, there are 24VDC locks available on the market, but nobody should use an un-monitored locks in an Access Control system. It defeats the purpose of having a locked door if you are unable to confirm if it is actually locked!!
U
Undisclosed #2
Dec 10, 2018I Agree, there are 24VDC locks available on the market, but nobody should use an un-monitored locks in an Access Control system.
Yes. Quite a few actually, just at Lockwood.
Certainly more than I would expect after reading
In Australia, all Access Control systems use 12 VDC.
as for
but nobody should use an un-monitored locks in an Access Control system.
I agree
TM
Ty Mullen
Dec 06, 2018As said above most hardware is 24vdc. 12vdc is starting to make a big come back because of PoE. Some controllers that are PoE are equipped with wet relays. Allowing the controller to supply 12vdc to the lock even though it is receiving 48vdc PoE. This can save time and money because you can bring a single CAT6 to the door.
Not only are more manufactures making 12vdc version they are also using different motors that consume less amps. Which is critical because the PoE controllers often can not supply more then 750 milliamps. Which is shared by the card reader, lock, and REX.
If we are using 12vdc (not in a PoE application) we like to put a big label on the inside to easily indicate that to future service techs.
U
Undisclosed #2
Dec 06, 2018Not only are more manufactures making 12vdc version they are also using different motors that consume less amps.
If they are trying to consume “less amps”, then 24vdc is the way to go, since it needs half the amps that 12vdc does, no?
TM
Ty Mullen
Dec 06, 2018Most access control controllers run on 12vdc. So they are taking 48vdc (PoE) and stepping it down to 12vdc to run the panel and card reader. As a result they are going to power the door locks with the already stepped down 12vdc. They are not going to convert the power in a second way just to run the locks. step down the power in two different ways.
12vdc locks have always been around (just not sold much). However a lot of them had to large of motors to work with the minimal amount left over in the PoE budget. So many manufactures started looking a micro motors specifically for PoE applications.
UI
Undisclosed Integrator #6
Dec 07, 2018Just pick either one and stick with it for your locks. Pretty much every lock will do both out of the box so it doesn't matter. For a decade I did everything on 12v and then for another decade switched over to 24v. The card still opens the door just fine.
UI
Undisclosed Integrator #7
Dec 07, 2018I always use 24VDC.
If you use 24VDC with 18AWG or larger cable and you are powering from the same location as your access controller, you will never have to worry about voltage drop UNLESS you exceed the 500' wiegand limitation which you should never do anyway.
TM
Ty Mullen
Dec 07, 2018That is one big benefit of going with 24vdc.
Just make sure that if you are using mag locks with push buttons and REX that you make all of your connections at the door not the panel. Because each cable that the power goes over is -500'. So if you have 3 cables now it becomes -1500'.
CK
Carl Kristoffersen
Dec 07, 2018No. That's not how this works...
It would actually be beneficial to have three different wires, as they would still be only 500' each and also would effectively have less power loss due to less combined resistance.
SD
Shannon Davis
Dec 07, 2018Wire from power supply ~500' into rex, wire out of the rex into button ~10', wire out of button into lock ~10', total wire length still within the 500' range. Of course always have your 30 second button last. I ran into a door one time where the rex motion was last and somehow against the laws of physics the constant 24VDC jumped over to the secondary relay of the motion thus you couldn't open the door now matter what you did.
TM
Ty Mullen
Dec 07, 2018Carl: Your saying that running separate wire all the way back to the panel is better and have less power loss.
500' of 18/2 - Mag Lock
500' of 18/2 - Push button
500' of 18/2 - REX Sensor
They are wired in series by interrupting the positive. The power is flowing back at forth from the door to the panel to the door to the panel to the door to the panel (3 full trips).
It is better to run a single 18/2 500' then make other runs around the door at 10'.
500' of 18/2 power
10' of 18/2 lock
10' of 18/2 button
10' of 18/2 rex
Then make all connection at the door.
Note: For simplicity I have neglected to include powering the IR Rex and other factors but that does not change what is happening to the lock power in terms of voltage drop.
CK
Carl Kristoffersen
Dec 07, 2018Looking at your first post quickly, I was initially thinking that your were saying each of those devices needed power, like the REX motion, and now realizing the button didn't. But I didn't think of a scenario as to someone running three separate wires for control as that is pretty much a non-starter, yet here we are.
SD
Shannon Davis
Dec 07, 2018TM
Ty Mullen
Dec 07, 2018SD
Shannon Davis
Dec 10, 2018
U
Undisclosed #2
Dec 07, 2018Just make sure that if you are using mag locks with push buttons and REX that you make all of your connections at the door not the panel.
Although it works, if you do it that way, how does the access control system ever know when the button was pressed?
Also, if you do run the button all the way back to the panel where it connects to a relay contact which controls the maglock power, that wouldn’t add to the resistance of the power run, right?
SD
Shannon Davis
Dec 08, 2018Typically code requires the button is a local mechanical 30 second break of the lock power not a request to exit signal. That is what the motion or crash bar are for. You wouldn’t know when the button was pressed but you get a forced open if you have a DPS as well. If you have a button with two relays in it, usually a pneumatic button, then you could tie the N/O side into the typical spare lock wires to an aux input to the system. I have had a couple of customers do this as people would press the button even though they didn’t need to for exit that way it didn’t count against their forced open report. Of course this is assuming you are running a composite reader lock group cable where the lock wire is a four conductor.
U
Undisclosed #2
Dec 08, 2018...the button is a local mechanical 30 second break of the lock power not a request to exit signal.
Yes, I assumed it was a REx button. 
U
Undisclosed #4
Dec 10, 2018UI
Undisclosed Integrator #8
Dec 07, 201824VDC
Joe Holland
Dec 10, 2018LifeSafety Power has found that the practice of 12 or 24VDC is geographical in nature with the US being primarily 24VDC and contries such as Canada or Australia being primarily 12VDC. 24V is better for line drop and allows a smaller gauge wire.
Power usage is the same at either voltage as locks are rated in wattage and most are selectable for 12 or 24VDC. A lock set to 12V however will draw twice the current at 12V than at 24V to develop the same magnetic energy. A six watt 12V lock will draw .5A at 12V and .25A when set to operate on 24V.
LifeSafety Power units offers TruWatt on all FPO supplies, a feature that delivers twice the current when the supply is set to 12V than at 24V. The FPO150 for example, is rated to deliver 12A at 12V or 6A at 24V to allow the integrator the same number of locks regardless of the voltage.
U
Undisclosed #2
Dec 10, 2018LifeSafety Power units offers TruWatt on all FPO supplies, a feature that delivers twice the current when the supply is set to 12V than at 24V.
Is this an uncommon feature?
Joe Holland
Dec 10, 2018Typically yes it is uncommon as most power supplies in the security world are based on amperage not power. For example 12 or 24VDC at 4 Amps. If based on power it would be 12V at 8 amps, 24V at 4 Amps. This allows the same number of locks to be powered whether 12 or 24V.
U
Undisclosed #3
Dec 10, 2018Ok..enough with life safety power, altronix and enclosure mounted power supplies. PoE controllers for the locks should be the technology that wins here. The locks need to advance in efficiency so as to rid us of all those enclosures with 1970's circuitry with automotive and glass fuses still being used.
UI
Undisclosed Integrator #6
Dec 10, 2018For an electric strike you could go with that but never with a mag lock or any other higher power device. I have many hundreds of doors on both technologies and without a doubt a lock on a regular power supply is more reliable. My systems can run just fine if the network goes down when using a traditional power supply but try that with a POE powered edge device running the lock.
Also you don't have fire alarm disconnects on a POE enabled device so no can do with mag locks unless you want to ignore code laid down in pretty much every building code book in the world.
U
Undisclosed #2
Dec 10, 2018Also you don't have fire alarm disconnects on a POE enabled device so no can do with mag locks...
Can do:
UI
Undisclosed Integrator #6
Dec 10, 2018Anything can be done but that doesn't make it right (or even legal). You can come up with any diagram you like but that one is a joke. Why would you want to shut down an entire system (network) as in OFF, dead if you had a fire alarm? If you had other doors with a strike NOBODY would be able to move through the building if there were interior doors since they would all be locked unless you put in all Fail safe hardware.
U
Undisclosed #2
Dec 10, 2018Why would you want to shut down an entire system (network) as in OFF, dead if you had a fire alarm?
It just turns off the devices on that switch, not the entire system (network). You could put only the systems that fail-safe on that switch. Even if not ideal in every scenario, it would certainly be sufficient in many cases.
Shannon’s Altronix solution is far more elegant for sure.
SD
Shannon Davis
Dec 10, 2018Here is an actual POE fire shutdown that can be used by Altronix. Adds costs to the system but in certain situations makes sense. Of course you have to install per fire code.
SD
Shannon Davis
Dec 10, 2018Unless a person has been a service tech most don't understand the difficulty of servicing a controller above the door. Everyone thinks having the panel at the edge like a POE controller is the best solution ever but from my experience this isn't always the case. Sure out in a warehouse or open area this is great but above the ceiling tile can be a real pain in the butt. First it always gets mounted somewhere that is hard to service, ie. directly above the door thus people are walking in and out while you are trying to fix something. Trust me it doesn't matter how many cones you put up they still need to walk through your work area. Second the location doesn't get marked so you spend way too much time finding it and third the location is marked but 3 years later they move furniture, build a wall or whatever then you can no longer get to the controller that needs serviced.
I walked a site a couple of months ago where individual controllers were installed in a warehouse that was wide open and the controllers were very serviceable. Great except for the fact at one point the customer decided to finally put up steel siding panels everywhere and didn't bother to leave a cutout or door for most of the controllers.
Sure a POE lock that is on the actual door is amazing but not always the answer or feasible.
Daniel S-T
Dec 10, 2018Great except for the fact at one point the customer decided to finally put up steel siding panels everywhere and didn't bother to leave a cutout or door for most of the controllers.
Hey, maybe that's what happened to that one Warehouse I did a walk through a couple years ago, 40 some controllers that could not be found anywhere in the building, lol
But to the main topic, I do agree. Neat for everyone that doesn't have to install/service them.
U
Undisclosed #2
Dec 10, 2018Now with the introduction of the revolutionary “McKinney PoE Ethernet Hinge” there’s nothing stopping us ;)
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