Lesson Info:

• Lesson Number: 1095
• Lesson Date: 2001-08-27
• Submitting Organization: DFRC
• Submitted by: Roy Tryon

Subject:

Description of Driving Event:

The Center has an existing campus complex of modular buildings fed by a main distribution panel (MDP) with 120-208 volt/3 phase power output. A recent project added 3 more buildings to the complex, each having its own 120-208 volt/3 phase power panel. The mechanical engineer specified HVAC units by specific brand name and numeric catalog number, "or approved equal". Embedded in that catalog number was a letter code that denoted the specific voltage for the HVAC equipment motors. In this case it denoted 480 volt power. The electrical drawings and specifications (provided by NASA) showed 120-208 volt power supply. Therefore, the mechanical subcontractor furnished and installed exactly what NASA specified and approved during product submittals. It was only when the HVAC equipment was actually installed in the field, and the electrical subcontractor tried to connect up the 208 volt circuit feeder that anyone realized that there was insufficient voltage to power the specified 480 volt HVAC motors.

NASA had several options: (1) Remove the 480 volt equipment and replace them with new 208 volt equipment. (2) Run new 480 volt circuits back to the campus main switchgear. (3) Install new additional step-up transformers for each of the 3 HVAC units. Due to constructability, cost and schedule impacts, option #3 was selected.

Lesson(s) Learned:

1. The design Project Manager must coordinate mechanical equipment with electrical power service.
2. The mechanical designer should not rely on very precise and specific brand name catalog order numbers when specifying long-lead, high cost equipment. When using more generic descriptions the designer should include an actually specification of the available power supply.
3. This mistake could have been caught and corrected during the submittal review process. Catching it there would have saved the additional contract cost or time. Submittal reviewers need to do more than just compare similar catalog numbers. They should also double check on all utility service connection requirements for major equipment.

Recommendation(s):

1. In the course of the submittal review process ensure that construction reviews substantiate both mechanical equipment with electrical power service requirements for major equipment during the design phase. Key point for better construction reviews is to focus on electrical and other utility service requirements for major equipment items.
2. Provide careful submittal reviews during construction. Make sure that the reviewer understands what every one of those specific model code numbers and letters means.
3. Avoid specific brand/model # specifications without also adding more generic and descriptive requirements to tell the contractor/supplier exactly what is needed.

Evidence of Recurrence Control Effectiveness:

1. Enter this problem/mistake into the NASA Lessons Learned Data Base.

Documents Related to Lesson:

Mission Directorate(s):

• Exploration Systems
• Aeronautics Research

Additional Key Phrase(s):

• Facilities

Additional Info:

Approval Info:

• Approval Date: 2002-02-12
• Approval Name: John Marcrum
• Approval Organization: DFRC
• Approval Phone Number: 661-276-2825