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Cat5 for power supply to MagLock

Discussion in 'Electrics UK' started by d000hg, 24 Jan 2020.

  1. JohnW2

    JohnW2

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    Pretty close (close enough!) - Mr Wikipedia says "24 AWG (0.51054 mm diameter; 0.205 mm²2 CSA)".

    Kind Regards, John
     
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  3. d000hg

    d000hg

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    It's just listed as a 12V PSU. Though we didn't buy it yet. Why would it be 13.8 not 12?
     
  4. bernardgreen

    bernardgreen

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    A 12 volt battery ( of the type used in alarm panels ) will be float charged at 13.8 volts hence the panel nd accessories have 13.8 volts when mains power is there to charge the battery
     
  5. d000hg

    d000hg

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    Ah I see. I think this is a mains -> DC converter PSU. There is an optional battery but I assume that's just a lithium battery.
    It's not an alarm system or supply, outside normal hours there will be a physical lock
     
  6. Speakercon

    Speakercon

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    Mag locks are typically powered from an alarm system style PSU with a lead acid battery backup. It's common to use alarm cable and cat5 from my experience (I prefer alarm as cat5 isn't really ideal in screw terminals). What sort of control unit is being installed?
    elmdene-tr-power-supply.jpg
     
  7. sparkymarka

    sparkymarka

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    It won’t be a lithium battery it will be something like above ....don’t forget with a maglock ....no power then the gate will be unlocked ...
     
  8. d000hg

    d000hg

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  9. bernardgreen

    bernardgreen

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    Is the MagLock one that requires power to hold the door locked or is it one that requires power to un-lock the door.

    If it a lock that requires power to un-lock then by using a battery and relay close to the lock the problem of voltage drop along a long cable is removed.
     
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  11. d000hg

    d000hg

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    Power to stay locked. You unlock the gate by breaking the supply

    My issue here is then you can't just switch the supply from the building to remotely unlock, if you cut the mains supply the battery will just take over :)
    Of course you can get around this using a separate control wire or wireless IR control box at the gate but we'd prefer to keep the gate end as simple as possible.
     
  12. bernardgreen

    bernardgreen

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    Problem with a "power to lock" system is that a battery is necessary to maintain the door locked if there is a power failure, These are ideal for locking "emergeny exits" as they unlock when power is removed either by manual switch off or loss of supply in an incident requiring emergency exits to be open.

    A battery backed "power to unlock" system is better for security on doors that are not part of an emergency exit route. With the battery located at the lock the lock can be released by a button / keyswitch at the door or remotely. A single pair cable can supply current to trickle / float charge the battery and also ( by polarity reversal ) control a relay that energises the lock to un-lock the door.
     
  13. d000hg

    d000hg

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    I assume they work differently too... power-to-lock is just a metal plate with an electromagnet, power-to-unlock must use a more traditional bolt/latch and the current pulls the 'bolt' like a solenoid or similar?

    One imagines the latter can be manually unlocked with a key or something in case of power-outage?

    I think our use it really doesn't matter much way we did it to be honest.
     
  14. JohnW2

    JohnW2

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    Yes, it could be done in those ways, but power-to-lock could obviously also use a solenoid and traditional bolt/whatever - and that might offer an advantage that a solenoid would probably require less power than would be needed to create a fairly 'brute-force-proof' lock which was just relying on an electromagnet+plate.

    As bernard has intimated, another approach would be to have a relay at the lock end (in which case 'power-to-unlock' could become 'power to lock' as far as the lock was concerned) - but that would require a 3-core connection (2 for supply plus one control core) unless one relied totally on a battery at the lock end.

    A third type of approach would be to have sequential system whereby alternate activations of a solenoid would 'toggle' between 'locked' and 'unlocked' (like many 'push-pudh switches'). That has the advantage that it only uses power very briefly whilst the door is being locked or unlocked, but there would gain probably have to be a third core, so as to allow a signal to come back to indicate whether the door was locked or unlocked.

    Fair enough. As bernard has said, it really depends upon the application and what one wants to be the default situation in the case of lost power - as he's said, different for 'emergency exit' and 'security' situations.

    Kind Regards, John
     
  15. d000hg

    d000hg

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    Cheers John. And Bernard too. Definitely the sort of thing you want to be aware of before you either end up locked in or having your back-door wide open to the public in a power cut ;)
     
  16. JohnW2

    JohnW2

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    You're welcome.

    I might perhaps add that with any of the approaches that have been discussed, one would ideally have at least one signal wire coming back to indicate 'the state' of the door/gate - since none of the methods would achieve anything useful if the door/gate was not 'properly closed' when the lock was activated remotely!

    Kind Regards, John
     
  17. d000hg

    d000hg

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    I didn't realise that was an option - hadn't looked at the maglock interface in detail. That would be a neat feature - would I be right thinking the same CAt5 cable could do this, I'm not sure if he would be expecting to use all the pairs of wires or if some would be unused/available. Perhaps he expects to do this anyway and that's another reason for using this, would it be standard practice?
     
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