Questions_and_Answers__3.doc

Memorandum for Record

The following questions were submitted on 26 and 27 April. Each question is accompanied by the answer.

Question 1. Ref – Specification section 26-13-01.

To date Current vendors are not able to provide spec compliant 25 CAIC.

Answer 1. The Federal Pacific Type PSI/II pad mounted switchgear provides 25,000 symmetrical rating (40,000 asymmetrical) at a rated maximum voltage of 17KV as required by paragraph 2.1 AIR INSULATED PAD-MOUNTED SWITCHGEAR in spec section 26 13 01. The 40,000 asymetrical rating is equal to the 25,000 symmetrical rating.

Federal Pacific has confirmed that this switchgear is available for sale to all customers and meets the specification for 25,000 symmetrical rating.

See specification SECTION 26 13 01 para 2.1 "IEEE C37.74 Shall be as manufactured by S&C PME pad mounted switchgear or Federal Pacific PSI/II pad mounted switchgear or approved equal." Note that the switchgear must be a "live front" PMS..

Question 2. The 25 KAIC is the rating called out in the specification 26 13 01 - 2.1.1. The primary vendor listed is S&C they have taken exception to this rating as their equipment is rated for 14 KAIC. We have received a quote from Federal Pacific with the same issue. I have not received any updates from Federal Pacific since requesting a spec compliant offer. See below for the S&C comments.

- We take exception to the 25KAIC short circuit and interrupting rating per 2.1.1, that rating is not available for PMH gear (required per drawings). Short circuit and fuse interrupting rating will be 14KAIC symmetrical. S&C does not offer a live-front pad-mount PMH design which provides a symmetrical interrupting rating above 14,000AIC. Note that all of the existing S&C PMH switches at Seymour Johnson AFB do not exceed 14,000AIC symmetrical.

- S&C recommends a short circuit study be performed in order to confirm the fault currents estimated at Seymour Johnson AFB. (This may result in estimated fault currents being confirmed to be less than 14,000AIC). S&C can perform this study at an additional cost.?

Answer 2. The Federal Pacific Type PSI/II pad mounted switchgear provides 25,000 symmetrical rating. Additionally this was confirmed by phone with Federal Pacific.

Short circuit and fuse interrupting ratings are available for the Federal Pacific Type PSI/II at the 25,000 sym. The spec sheets for cooper NX 200 amp fuses demonstrate that fuses exceeding the 25K sym (actual 50,000 sym rating) at 200 amps are available; additionally, the S&C SM-40 fuses can be obtained at 200 & 400 amps rated at 25K sym.

It is true that the existing PMH switches at Seymour Johnson AFB do not exceed 14,000 symmetrical but with new 750 Kcmil cable being installed from the substation for circuits 2 & 3 the former Edan study is no longer valid. The maximum indicated short circuit current available from the Edan E-Study using 350 Kcmil MV conductors was 11,000 amps Sym but this is no longer true when using a larger 750 Kcmil.

The specification table found in SECTION 26 13 01 para 2.1.1 is correct.

The Bid Closing date and time remain unchanged as well as the Bid Opening date and time. No amendment will be posted as a result of these questions.