Repetitive lightning issues with MCI interface port

[flyingtoaster]

Hello. Here's my first post!

I have a 2400 IPX and an AD-64 voicemail system. Both have been in place & run without issue for last 7 years. In the last 6 months, I have been having repetitive issues with lightining storms blowing out either the com port card in the ad64 or the port that the mci is setup to use on the interface card. I recently went with a USB attached com port device on the ad64 to see if that would solve the issue, no luck. Still lost the port on the PBX card in the last storm.

I have verified that the PBX is grounded (large 4 gauge cable going from ground lug on pbx runs to main water feed in building. Again, has been this way for last 20 years without issue)The PBX is powered by a large ratelco battery backup system.

The AD64 is plugged into an APC battery backup unit with surge protection.

Beyond that, I don't know where else to look. No other component is ever affected by the lightning.

Thanks in advance for any suggestions. -John

 

[OzzieGeorge]

I would be checking the resistance between the PABX earth and the power earth on the AD64 also check it between the water pipe and the electrical earth. You may need to call in an expert on the subject.

 

[flyingtoaster]

I did have an Electrician review the main ground from my switch room to the grounding location and he said it was ok. Before my 2400 went EOL, I had an NEC tech look at it and he saw no issues with the grounding within the PBX.

I'm tempted to wrap a piece of cross connect around the interface card mounting screws and run it over to the ground strip on the wall. Granted, if the chassis is grounded promperly, then its a waste of time.
I'm also tempted to drill a hole in the floor & hammer down a 4' ground rod & add a second ground leg from the PBX chassis to the rod about two feet away.

 

[OzzieGeorge]

I'm in Oz and we have serious problems here due to very sandy soil resulting in a poor earth mat, You need to consider cross bonding between the electrical earth and the PABX earth so that any difference in potential will equal out over that link rather than through your equipment. The following is a link to an article by an Australian expert and whilst it may not be totally applicable to your situation, it may give you some insight into what your problem is.....

http://www.titab.com.au/sites/titab.com.au/files/cabling_between_buildings.pdf

Whilst in the main it relates to connections between two buildings, if your earths are not cross bonded then effectively the same problems could apply. Then again I could be totally wrong, not truly knowing your situation.

 

[belevedere]

That has been an ongoing problem with the IO cards in the 2400. I am sorry to say that in 30 years of working with NEC 2400 systems, that is a weak link. A USB com port usually works on the voice mail. You just need to tell it what the com port number is for MCI in the VM. As for the IO cards, keep a healthy supply of spares. The system is out of production and out of support.

 

[flyingtoaster]

I have been trying to figure out what has changed in my system for this to start happening. After all, the system has ben in place for 20 years w/o issue. The only thing I came up with was just over a year ago, we stopped collecting and processing call accounting. The main reason was lack of use in light of cell phone usage. Plus, in those last few months, the PC that was collecting the data from the PBX, stopped communicating with it. (lightbulb) It occurred to me, the port on the interface card that was for call accounting must've gotten hit at somepoint, stopped working and I assumed it was a software issue. I unplugged that PC and so now where does the lighting go?, to the other com port which is voicemail.
Needless to say, I hooked up a sacrificial lamb computer to that other port again yesterday as well as I put the dead interface card back in the PBX next to it with an old PC hooked to that as well. My hope is, those other com ports will provide the ground needed to avoid the VM port getting wacked.
(I have also sourced a spare interface card online). If anyone has interface cards that they are willing to let go, LMK. Tx.

 

[OzzieGeorge]

If these "sacrificial" machines are closer to the PABX they may be ineffectual as the earth they connect to will be at a similar potential to the PABX and so will not be a good route for the surge to dissipate through!

You could look at an RS232 Opto Isolator to act as a break point between the PABX and the computer you want to protect.