Can you provide a picture of your meter when you get the reading? You are almost exactly drawing 10X the rated current. Sounds to me like a decimal error in the reading.
You likely chose to use DC for your strikes so that the system could be operated by battery backup. If you switch to AC for one or both of the strikes, obviously, that will no longer be an option. As the problem with DC is that your power supply is not capable of supplying the current to operate the strike, if you want to maintain the battery backup capability, one solution is to use a power supply that can supply enough current. As suggested in reply #16.
outofoptions:
You are almost exactly drawing 10X the rated current. Sounds to me like a decimal error in the reading.
I doubt this is the case - we actually tested with 2 different amp meters and both gave almost identical readings.
In addition, if it really was drawing 1/10th of the 3.3A on the meter, it wouldn't be causing a system power supply reset at the 5A peak.
correct
I think that this problem should not be 'solved' ( masked ) with this solution. With the very low resistance on the coil, I think that it would continue to drain current in an ever increasing manner, until either the power supply peak is exceeded ( like happening now ) or the 2 second that is coded for the coil to be energized has elapsed. Only difference with the old supply, was that it was capable of managing the short for the 2 seconds and didn't quite reach its peak.
If I am understanding this problem correctly, I think that the stress placed on the components in the old power supply by this action was a major contributor to its' demise.
I think that this problem should not be 'solved' ( masked ) with this solution. With the very low resistance on the coil, I think that it would continue to drain current in an ever increasing manner, until either the power supply peak is exceeded ( like happening now ) or the 2 second that is coded for the coil to be energized has elapsed. Only difference with the old supply, was that it was capable of managing the short for the 2 seconds and didn't quite reach its peak.
If I am understanding this problem correctly, I think that the stress placed on the components in the old power supply by this action was a major contributor to its' demise.
First off, you are assuming a "problem" where none necessarily exists. The current that your coil consumes on DC is a matter of Ohms Law for the most part. If you want to lower the current on DC then your option is to replace the strike with one that consumes less current. If the failure of the original power supply was from being overstressed, then it was misapplied in the first place and should be replaced with one with even greater ampacity, not less as you evidently did.
FYI
if you need measure current when strike is just on, ACS712 is disqualify. The di/dt sensor (normally DSP) is needed. i.e. ADE7763 ( cost ~4 at digikey). Oscilloscopes is work around, but not meter.
Thanks Papa G
I suppose that the "problem", or non-problem as you may be suggesting, is one of personal perception.
From my point of view, I have a striker rated 350mA for use on AC or DC, which I think should use around 350mA. The fact that my estimation of the size of power supply takes this into account, and I purchase the power supply, and it keeps failing because of the current being far in excess of the 'advertised' rating, becomes a problem for me - it's a matter of perception, you see.
Now that I think I understand the cause of the 'problem' ( now re-named to 'challenge' to suit various possible perceptions ), I can change things around to suit - will be running the striker from the AC adaptor.
I think that I really have to sincerely Thank everyone that has contributed in any way to this post - I have again learnt so much from this. I really appreciate all the time that you have all taken to reply.
My last question would be :
The wall fitting AC adapter ( 230V to 16VAC 1A ) has 3 terminals. 2 would be the live / neutral. The third is connected directly to the earth pin that plugs into the wall.
Would it be recommended to connect spare wires in the cable to that earth terminal, and then at the gate location where the strike is, connect the same wires to the metal gate frame that the strike lock is inserted into ?
My last question would be :
The wall fitting AC adapter ( 230V to 16VAC 1A ) has 3 terminals. 2 would be the live / neutral. The third is connected directly to the earth pin that plugs into the wall.
Would it be recommended to connect spare wires in the cable to that earth terminal, and then at the gate location where the strike is, connect the same wires to the metal gate frame that the strike lock is inserted into ?
If it's a transformer, the 16VAC secondary should have no relationship, electrically, at all to anything on the primary including earth. The ground terminal is probably there to satisfy the need to blow the fuse/circuit breaker should a primary wire get loose inside the adapter.
From my point of view, I have a striker rated 350mA for use on AC or DC, which I think should use around 350mA. The fact that my estimation of the size of power supply takes this into account, and I purchase the power supply, and it keeps failing because of the current being far in excess of the 'advertised' rating, becomes a problem for me - it's a matter of perception, you see.
Can you post a link to the data sheet for this striker that you are using?
Unfortunately not. This is Africa.
All I can tell you is the specs we have, and 'Made in Spain'
Brand name is not relevant, as I can probably buy the exact same thing with 3 or more different names.
DaveO:
[quote author=Papa G link=topic=163753.msg1227079#msg1227079 date=1367596340]
Can you post a link to the data sheet for this striker that you are using?
Unfortunately not. This is Africa.
All I can tell you is the specs we have, and 'Made in Spain'
Brand name is not relevant, as I can probably buy the exact same thing with 3 or more different names.
[/quote]
Okay, just curious. I wouldn't place to much weight on the data that you do have, in that case. Trust what you can measure and good luck with your project.
Many Thanks Papa G
I really have learnt SO MUCH from this forum. I am amazed at the number of regular replies by members whose level of knowledge I could only dream of reaching.
My project is moving forward and, strangely, I look forward to the next problem challenge 
DaveO:
Many Thanks Papa GI really have learnt SO MUCH from this forum. I am amazed at the number of regular replies by members whose level of knowledge I could only dream of reaching.
My project is moving forward and, strangely, I look forward to the next
problemchallenge
You're welcome, DaveO. Somebody proposed that
“The beauty happens in the process. Not the final product.”
Have fun!
Feedback :
I changed the power for the strike lock to a wall wart ( 16VAC ) as discussed, with one wire direct to a striker pin, and the other wire from the wall wart to a relay 'com', and the relay NO to the other striker pin. The relay is controlled by the Arduino ( well, via a transistor on the relay board, to be more accurate ).
Although the wall wart is only rated 1A ( the striker was drawing 3.3A on 12VDC ) it is working perfectly.
The only difference is that, on DC there was only a slight 'click' of the coil when it was activated, the AC powered coil makes quite a buzzing noise. Googling has told me that this is quite normal for an AC powered coil.
I then replaced the wall wart with a 9VAC 1A unit. ( the striker was rated 8 - 14 V, so I was a little concerned about the 16VAC wall wart output ) and everything still working perfectly.
Thanks to all for the education.
Had the opportunity to put my new knowledge to use again almost immediately. It struck me that, as the AC makes the striker coil buzz, why was the second gate not buzzing ? ( much heavier duty Cisa Lock ). The Cisa lock is drawing around 2A when activated.
Googled and found that the Cisa lock is designed for 12VAC, and they also make an optional extra bolt-on 'Booster' that can accept 12VDC, 24VDC and 24VAC. It also uses much less current than the 3A it says in the specs for the 12VAC, so I assume that it has some sort of capacitor that stores the charge until it is required. This Booster is said to work well with power from intercom systems, which is around 150mA.
So why is my Cisa lock drawing 2A from my 12VDC supply ? Quite simple - installed by an 'expert' it didn't have the booster added, and the 12VDC connected directly to the 12VAC coil.
This would explain the lack of "AC on the coil" noise / buzz, and also why the current draw is so high.
To make matters worse, there is no diode over the coil contacts. I am guessing that this would have also added additional strain to my old power supply.
That's the last time any 'expert' is going to install anything like this at my house again !! If he can't show me that he has a minimum of 200 posts on this forum, and evidence that he actually understand what he is talking about, he can't be trusted. I am just dumb-struck by the ( non ) expertise of the local installation techies - and that's with the company who has the best reputation in town.
Tomorrow I will disconnect the power to that gate lock until I can source and install the correct booster.
A coil that gets energised by/with AC would have an RC snubber across it, not a diode but performing the same function.