Take the 2-minute tour ×
Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. It's 100% free, no registration required.

I am looking for electric deadbolts for external steel doors - to place several of them on a door - one on each side (top, bottom, left, right) for extra security.

I want to buy just the deadbolt which opens when electric current appears on the wire, the electronics which will apply to current when an authorized user is at the door will be designed separately.

I need the electric deadlocks to be secure enough to be the only locks on an external home door in a high burglary rate area. And on the other hand be highly reliable in the sense that it'll always open when applied current, because if it doesn't I'd have to sleep on the doorstep.

The lock should operate on DC (not mains AC power) - to be able to use battery backup.

What parameters which I should look for in such locks, and what kinds to avoid?

share|improve this question
    
Four deadbolts and a steel door? Are you designing a bank vault? –  Doresoom Apr 3 '11 at 19:50
    
@Doresoom: You guessed it, LOL! But the bank is not too big and rich, so I have a budget of about 150 EUR/200 USD per deadbolt, any suggestions within that budget? –  miernik Apr 3 '11 at 20:08
    
Is this for your homes exterior door? Does the room/house you are trying to secure have windows? –  Tester101 Apr 5 '11 at 16:19
    
@Tester101: no, it doesn't. Its a bike shed out of 2 mm thick stainless steel, a steel door in the front and back for redundancy in case one of the locks in one door fail to open. –  miernik Apr 5 '11 at 16:35
    
That's some hardcore security for a bike shed! –  Tester101 Apr 5 '11 at 16:41

1 Answer 1

First off, I make no warranty of any of these suggestions. Especially if this is actually a bank...

I would be hesitant to completely rely on an all-electronic solution, since if there is a failure (which, frankly, is likely with a budget of only 200 per lock), you don't want to have to resort to a plasma torch or something to cut open (and destroy) the door to get in.

What seems like an interesting option to me though would be some of the RF-controlled keyless locks on the market. These look like a normal deadbolt, but have an RF remote.

enter image description here

What would be needed in whatever is chosen is the ability to hook into it, specifically, you need two things:

  • The ability to remotely control lock/unlock
  • The ability to sense if it's locked or unlocked

I'm going to assume that you have some type of microcontroller running the rest of this setup. You didn't specify.. but presumably you have something that has some I/O on it, the ability to connect it to the locks, and some software running to handle what I describe below. I'll also assume that you have an alarm and monitoring.

To control the lock, ideally, you could hardwire in to it, and be able to apply a signal to lock/unlock all the deadbolts. Less ideally, you could hack apart the remotes, and have your controller effectively press the buttons on the remote(s) to lock/unlock. This adds unreliability since you're dependent on an RF signal.

Since these are keyed locks, you have a nice backup mechanism if everything fails: use the 4 keys to open the locks (and note, you'd need to be sure they're 4 separate keys).

Of course, since they're keyed locks, they're also susceptible to being picked/bumped. To try and combat that, what you can do is have your controller monitor each lock individually. If any of the locks ever open when the controller didn't tell them to, then it should trigger an immediate alarm (consider: someone is likely to pick/bump one at a time). If this is an exterior door, then this is your first line of defence, unfortunately. If it's an interior door, then you should also have motion and other door sensors that will hopefully trigger before someone gets to this door.

You also need to consider all other aspects of physical security. You're only as secure as the weakest point, so if someone can break through a window or wall or vent then it doesn't matter how good the door is. Physical security is also just a matter of time: eventually, you can get through anything. That's why I suggested having an alarm system connected, which is both a deterrent, and triggers a police/whatever response. Consider: safes, even high-end ones, are rated by the time it takes to crack them: your door will be no different. Having video cameras probably helps as well, both as a deterrent and to help catch people afterwards. Your video and security system also need to be protected, so that they can't just be disabled/destroyed.

On the other hand, too much security and you actually can attract attention. I've heard that the houses with extra locks, security cameras, etc, are often targeted by thieves since they look like they have something valuable worth protecting.

share|improve this answer
    
Well, thanks for lots of ideas, but unfortunately most of them don't apply to my situation, for example: backup will be provided by a second door on the other side of the building, and the building has no windows. Specifically my question is only about the issue of finding the most reliable deadbolt which will open given 12VDC electric current, for other parts of the setup I already have lots of solutions. But thanks anyway. P.S. I noticed some electric deadbolts rated with "holding force" in kg (or lb), what value of "holding force" should I aim at? How good is 1000 kg? –  miernik Apr 5 '11 at 1:55

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.