Which is Cheaper?

[charlie b]

Before I try to talk a client out of their requested design change, can I get some opinions on which of the following two options is cheaper (including materials and labor)?

Situation: Lab building with four stories above ground level. Main communications room (MDF) is on the ground level. A separate, smaller communications room (IDF) is on each of floors 1 - 4. Each IDF will require seven branch circuits to supply the equipment racks. All four IDFs are located in a vertical line, one above the other, and there is a dedicated chase for the conduit runs.

Option 1: Run all 28 branch circuits (7 per floor, 4 floors) from a panel in the MDF.

Option 2: Run four feeders from the MDF panel to supply four 12-circuit branch panels, one on each floor. Run the branch circuits within each IDF from the panel in the IDF.

 

[chris kennedy]

Are you or the customer specing dedicated grounded conductors or IG's?

 

[nakulak]

its hard to say without the feeder sizes and footages. larger feeders add up quick. don't forget to consider option 3 which is putting a room on every other floor.

 

[chris kennedy]

don't forget to consider option 3 which is putting a room on every other floor.

I already PMed Charlie option 3. Serve floors 1 and 2 from panel on 1 and serve floors 3 and 4 from panel on 3.
Again, I couldn't bid this unless I knew how many conductors are required by specs.

 

[satcom]

In my opinion, price should have nothing to do with the choice, efficent and compliant work should direct your choice.

 

[Volta]

I think that it is probably close enough in cost to simply go for the convienience factor of a panel in each room, with the ability to add a few circuits easily. Likely cheaper (for the owner/occupant) in the big picture.

 

[Smart $]

Option 1 will likely be cheaper.

Option 2 will require 4 extra breakers (likely 3-poles), 4 additional panels plus extra installation and termination costs on labor. I doubt if the difference in wire, conduit, and their installation costs will afford any major offset to the aforementioned costs.

 

[charlietuna]

Bingo satcom! Which system is best for your customer's needs and allows for expansion. Your customer needs your professional input, weather you do the job or not!

 

[quogueelectric]

Option 1 is definitely CHEAPER but option 2 is not that much more and a much better job from a reliability standpoint. One surge could take out the entire system the opt 2 is more compartmentalized. One paperclip on the 3rd floor will not take out the entire network. Would also depend on what you need to do to fireproof floor penetrations with the branch circuits. Can you just sleve it in emt or do you need to pipe the risers out and firecaulk??

 

[charlie b]

Many thanks for the replies so far. Let me address some of your comments.

• The customer wants Isolated Grounds for all circuits. That means 4-wire branch circuits, with one wire (IG) going back to the distribution board. That board is in the electric room adjacent to the MDF on the ground floor.
• I intend to specify dedicated EGCs, since this is communication equipment, and I don't want them to have to turn off three circuits to work on one.
• The floor to ceiling heights are about 14 feet. The branch circuit conductors would be #12, and the feeders to 12 circuit panels in each IDF would be based on 60 amps (I don't know the wire size, and I don't have a code book at home).
• I don't know if price is the basis of the client's present choice (which, by the way, is Option 1). I don't know exactly why the client wants this choice, but I don't like it. I want to talk him into Option 2, or perhaps Option 3, and I am grateful for that suggestion.
• I agree with, and plan to use in my argument, the notion of the convenience of having a local panel to add more circuits.
• I hadn't thought of the notion of a paper clip taking out the entire system. This is an optional standby load, so it need not be selectively coordinated, but as a good design practice, I think it should be. So this is a good reason to push for separate branch circuit panels.
• I believe that firestopping is not a player. There is a 2x2 foot opening in each floor level in a chase that is dedicated to conduit run. I don't know if this area will be fire-stopped after any and all conduits are installed. But it would make little difference, even if firestopping is installed, whether there are feeder conduits (a bit larger, and fewer of them) or branch circuit conduits (more, and smaller).

Thanks again.

Charlie

 

[wireguru]

instead of options 1 and 2, what about running one set of feeders vertically using panels with feedthrough lugs at each IDF. Seems that a single set of AL feeders and some panels with feedthrough lugs would be alot cheaper than 4 sets of feeders or up to 60 vertical feet of conduit and branch circuit conductors.

 

[bjp_ne_elec]

I definitely agree that option 1 is cheaper from a material standpoint, but from a labor and logistics standpoint (thinking future expansion), option 2 is the best - so I didn't vote. Being cheaper always isn't better - and I'll leave it at that.

 

[emahler]

In my opinion, price should have nothing to do with the choice, efficent and compliant work should direct your choice.

hey les, good to see you, but I disagree....

customers budget needs to play into the design...

we just bid a project that was designed like a Ferrari...and priced like one...

problem is, the end users budget was only for a Cadillac, so all bids were $1m over budget...

it became a VE fest and a re-bid...quite frankly, the A/E didn't do their job properly....and did the customer a huge disservice...

we spent the last week coming up with a rebid, and now we find out in the next day or so, if our apple VE is better than the other guys orange VE or the other guys banana VE...

and the customer now has to decide which GC designed a better project than the A/E they paid a lot of money to did....

 

[LarryFine]

customers budget needs to play into the design...

If cost is a primary consideration, the best solution is to price it both ways, rather than ask for educated guesses.

 

[charlie b]

Many thanks again for the replies and the votes. I have sent the client a recommendation that we go with option 2. My basis was that the initial costs are roughly comparable, with option 1 being a bit cheaper, but that the first time you need to add one more circuit in any IDF, the cost and easy of running a conduit within the same room is much more favorable than running a conduit up four floors through a vertical chase. Also, there is now some talk of power monitoring. It would be easier to monitor power used on any of the IDF rooms by measuring a single feeder to a branch panel, rather than measuring seven or more separate branch circuits.

I'll let you know what the client decides to do.

 

[hardworkingstiff]

My customers always gulp at the costs. I tell them they will soon forget what the system cost, but they will have to live with the operation for the life of the system. If it's not so good, that's what they will be living and soon they will forget they saved money.

Least expensive is not always the best value.

 

[emahler]

it's not about being cheap or cheaper...over engineering a project so that it is out of the customers budget, wastes the time of the engineer, customer, vendors and every contractor that spent time bidding the project to find out it's not feasible.

a realistic look at the costs by the A/E will reduce costs via changes in SOW without wasting the time of 2-10+ contractors and give the customer a better product for their dollar.

 

[satcom]

I think we should install the best price, even if the design is poor, and the efficency is bad, after all us making a buck and getting the job is number one, no one really cares about quality, or the cost of operating a poor design over time, just get his money now and don't worry about workmanship, or cheap material, just get in there at any cost, and bid low and get out as soon as you can, keep up with the times.

 

[emahler]

I think we should install the best price, even if the design is poor, and the efficency is bad, after all us making a buck and getting the job is number one, no one really cares about quality, or the cost of operating a poor design over time, just get his money now and don't worry about workmanship, or cheap material, just get in there at any cost, and bid low and get out as soon as you can, keep up with the times.

Your sarcasm is 180 degrees from my point.

 

[LarryFine]

Your sarcasm is 180 degrees from my point.

I have the funny feeling he knew that.