Hello Mike,
There is no list that exists for accredited approval agencies. There is no governing body that accredits approval agencies. Accreditation services for testing labs exist, but not certifying/approval agencies.
The IBC definition for an approved agency is outlined in section 1703 of the code. An approved agency must be independent from the equipment manufacturer (Section 1703.1.1), must have adequate equipment to perform testing (Section 1703.1.2) and must employ competent personnel educated in conducting, supervising and evaluating the testing (1703.1.3).
Hope this helps.
Regards,
-Ani Natekar

The transfer switches are required to meet the same criterion as for seismic and wind loads as the rest of the power system. They would also be required to undergo the IBC certification and should have a label stating the same.
Check for applicable exemptions. The following components
may be exempt from complying with the code:
• Mechanical and electrical components in seismic design category B.
• Mechanical and electrical components in seismic design category C provided that the component importance factor Ip = 1.0.
• Mechanical and electrical components in seismic design category D, E, F where the component importance factor is 1.0 and either:
a. Flexible connections between components and
associated ductwork, piping and conduit are provided.
b. Components are mounted at 4 feet (1.22 m) or less
above the floor level and weigh 400 lb (1780 N) or less.

In the IBC 2000 and 2003 versions of the code, approved agencies need to be employed to do the actual testing and analysis. The agencies guarantee through independent review and analysis that equipment will meet the specified design standards. The manufacturer of certified equipment must supply equipment labels indicating the agency that has certified their product. The 2006 version of the code implies that manufacturers can “self-certify.” However, when labeling of equipment is required, it still needs to carry the designation of an approved agency.

The use of seismic isolators does not mean the equipment is IBC compliant. The confusion with seismic vibration isolators is that people often refer to them as “seismic isolators.” This term infers that their intended function is to isolate or reduce the effects of a seismic event. A seismic vibration isolator is not designed to reduce these harmful effects. At best, properly designed seismic vibration isolators will not amplify the effects of the earthquake into the system; however, they will transfer the seismic forces from the building structure into the equipment. This is the very reason that equipment manufacturers are analyzing and testing their equipment to meet certain seismic design forces. If seismic vibration isolators actually reduced the g-levels into equipment, the building codes would require everything to be “seismically isolated” rather than be designed to survive the effects of an earthquake.
 
Seismic vibration isolators do have a function when it comes to a properly designed seismic system. When vibration isolation is required on a project to minimize the harmful noise and vibration created by a generator set from entering the building structure, then seismic vibration isolators are required in seismic areas of the country. A properly designed seismic vibration isolator will reduce the noise and vibration emanating from the equipment during normal operation and will also keep the equipment properly attached to the building structure in the event of an earthquake. This style of vibration isolator must be captive in design and constructed to handle the overturning moments of the generator set when a seismic design force is applied to the center of gravity of the equipment. The design should incorporate no more than a ¼” gap in the horizontal directions and a snubbing device to minimize the amplification of the earthquake forces into the equipment.
 
If vibration isolation into the structure is not a concern of the design engineer, then the requirements for the project should only be proper attachment to the building structure. This includes analyzing the resulting overturning forces of the generator set based on the seismic site conditions of the project and then properly selecting an anchorage that can handle these forces.