Answers_to_Venders_questions_to_PDC.docx

Answers to Venders questions.9/14/15

Vendor 1 We would use distribution blocks to properly distribute the power to the three different breakers to stay within code. I would also recommend a breaker or disconnect for the primary side as well. I would like to see if they have a spec for the AIC rating for the breakers that they are requesting. I would recommend increasing the size of the transformer to a 225 kva so that it meets your breaker size on the secondary side."

Ans. The distribution blocks are acceptable and the transformer should stay the 150 Kva. The input cables would be disconnected before any repair work is to be done, so that we don’t need a disconnect on the primary side.

Vendor 2 "Here are our questions that we need clarification on before submitting a proposal:

1. 3.1.2, B., a), 1. and 2.

a. You cannot have a distribution panel that is rated for 600 amp 3 phase 4 wire that contains items 1 and 2.

a. ans. Separate the input from the output.

b. The 3-pole 200 amp, 480 VAC main breaker would have to be a separate panel board from the 3-pole 200 amp 208 volt branch circuit breakers. I also assume that having the breakers listed as 240 VAC is only for the KAIC rating of the breakers.

b. ans. A separate panel board is acceptable.

c. The 3-pole 200 amp, 480 VAC main breaker would feed the 150 KVA transformer primary circuit. We propose supplying a three phase 200 Amp, 480 VAC enclosed circuit breaker in a NEMA 3R enclosure with lockout tag out means fed from the three male receptacles mounted on the rear of the enclosure.

c. ans. We don’t do any work on the unit without disconnecting the input cabling so we don’t need lock out requirements.

d. We propose providing a grounded connection point adjacent to the three male receptacles for a ground connection to the enclosure from the source. This is a 1/2-13 stainless steel stud with nut and washer. I do not see the referenced section in the specification under 6.4.1.6 that refers to section 3.7.11 for more specific information.

d. ans. See paragraph 6.10.11 which should refer back to 6.4.1.6.

e. Instead of having an actual panel board for the three 3-pole 200 amp 208 VAC breakers (due to the size requirements we also propose using three enclosed breakers, NEMA 3R connected together with a wiring trough also rated NEMA 3R so we do not lose the necessary wire bending radius. These breakers would be fed from the secondary of the transformer and have a neutral bus inside the enclosures and ground connections.

e. ans. Acceptable

f. We also propose having the wiring for the receptacles covered by a sheet metal enclosure with the feeds in flexible metal conduit so they are grouped together with the ground and neutral conductors as required by the NEC to prevent excessive heating. The sheet metal cover would protect any maintenance personnel from incidental contact with the receptacle wiring. It would have a removable cover.

f. ans. Acceptable

g. The size of the enclosure needs to be large enough to meet the NEC clearance code for access to the transformer (3 ft.) from the transformers removable access cover. This clearance also has to be met for the enclosed breakers and the receptacles with the sheet metal cover removed.

g. ans. Free space not required in front of the transformer because the input cables will be disconnected before any internal work is to be will be done.

h. The NEC also says there must be an access to the equipment for maintenance. The drawing contained in appendix B does not show a ladder or other means of access to the equipment. Our detailed operation instruction will require the main breaker to be locked out prior to any maintenance being performed which should make the 3' requirement by the code null because there will be no live equipment.

h. ans. We don’t do any work on the unit without disconnecting the input cabling so we don’t need lock out requirements. And there should be panels that could be opened to do any repair work.

i. Section 6.5.16.1 states that the enclosure will be lifted by crane and does not mention being lifted by fork lift. Section 6.10.7 states that the enclosure should be transportable by overhead crane or fork lift without imbalance. For clarification are both required?

i. ans. Yes, both are required

j. Appendix A shows the Integral Lifting Attachment ILA to be at the top of the enclosure. Appendix B Physical Configuration shows the ILA to be at the bottom of the enclosure. Section 2.2 of appendix A calls for a lifting plan to be included. This will require a spreader bar attachment for lifting the enclosure with a crane. Do we need to include this with the enclosures? If so will one be required or six?"

j. ans. One for all six used by our riggers.

Vendor 3 "We had a couple immediate questions, in regards to physical configuration on page 28 (Appendix B).

1) How close does this layout have to be followed?

1). ans. As close as possible.

2) The lifting points in this drawing are way below the center of gravity for the unit which is in direct contrast to Appendix A 4.1. Which is correct?

2). Ans. One spreader bar for all six units.