If you are looking for a lock for a home safe I would strongly recommend avoiding the ESL-10 by American Security Products. I had two of these locks fail in the same manner in a 17 month period.
I purchased a safe in April 2009 and had an American Security Products ESL-10 lock installed on it. Everything worked great until around August of 2010. I went to open my safe but the combo was rejected. After several failed attempts I tried the default combo (1-2-3-4-5-6) and that worked. Somehow the lock had reset itself (not a comforting feeling). I then changed the combo back to my numbers, it worked.
A few days later (while I was sleeping) I heard some "chirps" coming from the safe. These were coming at seemingly random times and last a few seconds. I tried to open the safe and once again it would not work, I tried the default combo and that did work. Clearly something is not right at this point. I changed back to my numbers and that did work again.
I went away for a few days, only to come home to go into the safe and once again it is acting up. However this time the default combo did NOT work. The lock was emitting tone sequences that are not defined. I made many attempts to try and get the safe open with no luck. At this point I am quite angry and also facing a big expense to have this (expensive) save opened. The lock was chirping often and randomly, I was not able to sleep so I pulled the batteries out. The next day I put the batteries back in and by some miracle the safe opened with the default combo. At this point I took all of the contents out and move them to another area (I have no trust in this lock now).
The lock was about 4 months out of warranty. I called the AMSEC tech support line and the first person I talked to was of no real help. The basically said there was nothing they could do. The person said they have no reports of locks acting like mine (however I seriously doubt they'd admit any issues to me). I hung up with this person and waited maybe 1/2 hour and called back and asked for a supervisor. I did eventually speak to a lady (now retired) and she was much more helpful, and said that they would send me a new lock. I was quite please with this.
Several weeks went by and nothing showed up at my door from AMSEC. I e-mailed the person I had been dealing with and got no response. I called and finally got back in touch with her. She seemed to have little recollection of our previous discussions, I sent her back the e- mail string which documented the course of events. Apparently someone "dropped the ball" on sending out the new lock. The new lock did show up about 3 or 4 days later. I installed it and it worked fine. Problem resolved (or so I thought).
About one month later this new replacement lock started chirping like the first one! This occurred at around 1:30am, keeping me awake. I tried to get into the safe but the lock was acting even more erratic than the first one! Sometimes numbers would respond with a beep and sometimes not. The default combo would not work. Random chirps and beeps were coming from the lock. Now I was even more angry due to once again facing a potential large bill for forcibly opening an expensive safe. I pulled the batteries out of the lock as the frequent random chirps were very annoying.
The next morning I re-installed the batteries. Long story short, the safe opened on the default combo. However, I did NOT re-lock it, instead I removed all the contents and moved it to an alternate location. There was no way I was going to trust this lock again.
I called AMSEC and asked to speak to the person that had helped me out, however the receptionist told me she had retired. I asked (and got connected to the voice mail of) a person who replaced her. I left a message and asked her to call me back. She never did.
Failures do sometimes occur in electronics. However, getting TWO identical failures on TWO separate items is extremely unlikely (for products that are made well). The odds are probably in the tens of thousands to one. These huge odds indicate to me some kind of internal problem with the ESL-10. Could I have beaten 10,000 to 1 odds? Possibly. However I will NEVER trust another AMSEC lock. I have replaced this lock with a mechanical one (a different brand).
Incidentally, my locksmith said that for his personal safes he uses only mechanical locks. He stated that people like the convenience of the electronic locks, however they do fail at rates much higher than mechanical locks. I am sure that there are many AMSEC ESL-10 locks out there that do work. My experience with the AMSEC ESL-10 has been miserable, greatly aggravating and costly. I will never use an AMSEC lock again. Ever.