ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Increasing demand factors in residential
by gfretwell - 03/28/24 12:43 AM
Portable generator question
by Steve Miller - 03/19/24 08:50 PM
Do we need grounding?
by NORCAL - 03/19/24 05:11 PM
240V only in a home and NEC?
by dsk - 03/19/24 06:33 AM
Cordless Tools: The Obvious Question
by renosteinke - 03/14/24 08:05 PM
New in the Gallery:
This is a new one
This is a new one
by timmp, September 24
Few pics I found
Few pics I found
by timmp, August 15
Who's Online Now
1 members (CoolWill), 250 guests, and 13 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Joined: Dec 2001
Posts: 440
Likes: 3
Member
I just started the process of bidding a 12.5 KV project. We had a "walk through" today, and I have to tell you that I feel like I'm in over my head, but upper management is pushing me to bid this project, and with my limited experience with voltages above 480, I'm going to put my best toe....I mean foot.... forward, and press on.
Labor units, reference materials for this type of application, etc, etc are really waxing heavily on my mind. Any advice (other than becoming chemically dependant) would be obliged.

Most Humbly, and Lostologically Yours,
Doc


The Watt Doctor
Altura Cogen
Channelview, TX
Joined: Jan 2002
Posts: 122
W
Member
Hi Doc, I have had success using the means book for a pricing guide. As long as I can price each componet from the book that has allowed me enough money (including profit) to sub it out to a high voltage specialty contractor. Wirewiz

Joined: Dec 2000
Posts: 4,294
Member
I'd try getting some bids for that portion of the work from guys that do this on a regular basis. Then add your%.
Is the 12K all the project??
I, too have personally done only a few jobs with voltages above 480 other than ducting them.
It's almost like being an apprentice again.

Joined: Dec 2001
Posts: 440
Likes: 3
Member
wiz,
I'm familiar with Means. As a matter of fact I have a Means book at the office. I guess part of the problem is, that in situations like these, I'm not even sure of "what" questions to ask. In 600 volt and lower applications, I have the experience that tells me when there are questions that I need answered.
electure, it is like being an apprentice again. As far as the majority of the project is concerned, it is just running 4" RMC. The problems come into play...well. Here is an example: A critical part of this project requires us to cut into (2)existing 12.5 kv concrete encased feeders, install an above ground tap box, and splice into the feeders. Here's the catch. The building being fed by the feeders can't be shut down for longer than a day or so. This project is for a college. Now, the feeders are a normal, and an alternate supply for the same switchgear.
My first thoughts were to set the building on alternate, and pull the normal feeder back, cut in half of the duct bank, install the tap box, repull the normal feeders, make up the stress cones, put the building back on normal power, and repeat the process for the alternate feeder. This would require our electricians to work in an energized switchgear, and for the connections in the tap box for normal power, the alternate source would be energized as well. I don't want them working in this gear while it's energized.
I'll post more as I progress through this project.

Regards to All,
Doc


The Watt Doctor
Altura Cogen
Channelview, TX
Joined: Dec 2001
Posts: 440
Likes: 3
Member
I thought I would post an up date for those who interested in medium voltage applications.
A basic run down of my take off:

(4) Sectionalizer Terminals 15 KV, 3 phase, RTE 450LOOK29A, with 15 KV Load Break Elbows, 4-way LBC's (LBC-4) and all fittings w/stainless steel mounting strap

(1) New MCC with more motor starters than I want to list

Refeeding (2) new chillers.

Adding an 800/3 circuit breaker to existing GE switchgear, not to mention the feeder that goes with it.

(3) Toshiba VFD's

Several Disconnects

(2) Pad-mount/dead-front, 750 KVA, 3 phase, 12,470 primary, 480/277 secondary, 65 deg C temp rise, mineral oil filled with HV Surge Arrest

11,000 feet of 4" conduit (PVC, RMC, and EMT)

12,000 feet of 4/0 awg Okonite 15 KV single conductor cable

(66) Stress Cones

etc, etc, etc

The above is a "quick" list of some of the major items.

I don't know what the final tally will be, but I'm guessing it will break the 6 digit barrier. I have a Square D rep. coming in on Monday to help me insure the equipment is correct.

Kilowattingly Yours,
Doc


The Watt Doctor
Altura Cogen
Channelview, TX
Joined: Aug 2001
Posts: 599
N
Member
Doc,
I have been actively pursuing an education in high voltage systems for many years. I finally received EC&M's Medium Voltage Power Systems a few days ago (ordered 6 months ago). I haven't gotten far into it yet. I will be looking forward to more posts from you on this topic!

Joined: Apr 2002
Posts: 2,527
B
Moderator
WD, are you planning to farm out the terminations or do them in-house? Some specs call for the installer to have five years of experience. The NEMA/AEIC DC tests will quickly flush out workmanship that is not “antiseptic” or materials that are improperly sized. Also, make sure to get the exact termination materials needed for your cable. Elbows are often intended for “utility” URD-type cable, and need special attention {and adapters} for use with “industrial” tape-shielded cable. There are several varieties of cable construction—make sure you’re getting the one that the engineer/facility has spec’d. Okonite is usually of good quality but some others can have a real problem with outer semicon that is not adequately free-stripping. Verify that you are specifying the right shield-grounding assemblies. Minimum bend radius on shielded cable during installation and as-left will save premature failure. For smaller jobs, it may be more convenient to use individual cable-prep kits as opposed to bulk materials. Plan on following specs for all grounding details to the letter to save rework. If you have to furnish DC testing as part of your contract, talk to several outfits if available. They probably can advise you on any concerns you have about splicing and terminations. One other thing—some cable manufacturers can be a bit ‘snobby’ to contractors that are new to this side of the business, but MV work can be profitable compared to 600V-only work.

Joined: Dec 2001
Posts: 440
Likes: 3
Member
Nick, Bjarney,
Gentlemen, thanks for your input. I submitted a bid for this project about 3 hours ago. It was a "nail bitter" because my supplier didn't get my quoted materials in until the last minute. I will let you know some of the other details later. I normally don't get very "worked up" about submitting bids, but this one, was an acception.
I've learned a few things, and if I do another one of these MV propsals again, I'll know more about what to do.

Best MV Regards,
Doc


The Watt Doctor
Altura Cogen
Channelview, TX
Joined: Dec 2001
Posts: 440
Likes: 3
Member
Nick, Bjarney,
There were 3 electrical (sub) bidders on this project. The mechanical contractors were the "prime" bidders.
The bid tab came back as follows:
contractor #1 $443,667.00
my company $458,300.00
contractor #3 $478,000.00
Here is the catch, and I might add a very important lesson in the bidding process, the numbers are not apples to apples.

Contractor #1 included #3 & #4 rebar for the duct bank, but they excluded the (3) Toshiba freq. drives.

We included the freq. drives, but excluded the rebar. Now, if you add the rebar back in, and deduct the frequency drives from my proposal, my number is actually lower than contractor #1. Notice:
Base bid $458,300.00
Rebar $--3,400.00
Drives ($-19,400.00)
Total $442,300.00

Contractor #3 had other inclusions, and exclusions that I'm not aware of, but less than $2,000.00 spread on this size project is not bad. I will admit that there were plenty of guesses on my part. I'm not sure if my now former company is going to get the job, or not.

Kilowattologically Yours,
Doc


The Watt Doctor
Altura Cogen
Channelview, TX

Link Copied to Clipboard
Powered by UBB.threads™ PHP Forum Software 7.7.5