The grounding post is critical. I can't stress that any better. Absolutely critical that the system be properly grounded. If it is grounded properly no need for ground prong on the power supply.

Second thing is clean power. A cheap APC 350 or larger for the S-Class is sufficient as long as it is the Modified Sine Wave version.

Never had a heat related problem.

It appears that you have hands on experience with telephone systems but may not have ESI experience. If you don't have someone ESI certified within your organization you need to develop a relationship with one. Coming here was an excellent move.

Question: Since this is your original visit to Sundance Tech-Talk, was it because we are the only one (I know of) that has ESI technical knowledge?