Questioning the Engineer

[shockin]

I have a situation where the engineer is proposing an installtion that I don't believe is code compliant. Please review the situation below and tell me if I'm off base.

I have one 1600 AMP disconnect that is going to feed two 1200 AMP MB panels. The feeds for each panel contain 1200 amps worth of conductors. The distances of the feeds are 40' and 150'.

IMO this greatly exceeds the distances permitted by the NEC "tap" rules, therefore the feeders must be protected at 1200 amps each by replacing the 1600 amp disconnect with (2) 1200 amp OCD's. Am I all wet? The 2005 NEC does applies to this situation.

I have questioned the engineer on this and he tells me that it is compliant.

Thanks for your input.

 

[mdshunk]

The feeds for each panel contain 1200 amps worth of conductors.

As part of the ongoing theme of not believing what I read, can you jot down what conductor type, gauge, and number of conductors he proposes you use?

 

[infinity]

As Marc said some further information could help to solidify an answer, but on the surface you're not all wet.

 

[shockin]

As part of the ongoing theme of not believing what I read...

Understandable - I don't recall exactally what they were when I did the analysis of the existing system. (The feeders and MB panels are existing.) The engineer is 1500 miles from the site and has never visited, so I did the leg work for him a year ago. This wasn't suppose to be part of the scope when we started, so a detailed on-line of this part of the existing service wasn't done.

He only recently asked what size I thought the feeds were. We haven't "suited-up" to go investigate, so therefore he has to assume at this point it is 1200 amps because that's what I told him. These were actually the old service entrance conductors. and I am 100% certain that the feeders contain 1200 amps worth of conductors based on a number of reasons, but I understand why you would question that.

 

[jim dungar]

These were actually the old service entrance conductors. and I am 100% certain that the feeders contain 1200 amps worth of conductors based on a number of reasons, but I understand why you would question that.

If these are old service conductors, are they located "outside" of the building? Many older 1200A service conductors are not sized adequately for equivalent branch circuit use (i.e. 3-500kCMIL = 1140 not 1200A).

 

[drbond24]

Engineers are always right and should never be second-guessed. :grin:

 

[charlie b]

The only tap rule that has any hope of applying is 240.21(B)(5). Can you tell us if that rule does apply?

By the way, as an engineer I will tell you that I consider it your duty to tell me if you think I issued a design that contains a code violation. I own't bite, I promise.

 

[shockin]

If these are old service conductors, are they located "outside" of the building?

This is the reason I initially ruled this exception out. Charlie mentioned this as well. To me when the code reads "outdoors" as it does in 240.21 (B) (5) it would mean outside the foot print of the structure. These conduits do run under the existing building, so I thought it wasn't permisable.

Anyone have a definition of "Outdoors?" If it said "outside" I would agree that under the slab is permitted, but with "outdoors" I don't think it is. Agree / Disagree?

 

[charlie b]

. . . the code reads "outdoors" as it does in 240.21 (B) (5) . . . .

Two things to note. First, the title of that sub-paragraph uses the word "outside." So I don't think you need to be concerned over the difference between outside and outdoors. Secondly, it refers you to 230.6. So if the conductors meet the description of 230.6, then the tap rule can be applied.

 

[shockin]

Engineers are always right and should never be second-guessed. :grin:

I know that you're joking, but a lot of engineers do not appreciate being second guessed. No matter how politley you phase the question. I use to think we were all on the same team. I have come to realize that the engineer is the coach of the team, and you NEVER question a coach's decision.

If you really want to get them mad, offer some "value engineering" ideas to reduce your electrical bid once the initall budget come in too high.

 

[shockin]

Secondly, it refers you to 230.6.

I actully meet the requirements of (4) (a) so I didn't need to read down to (c) where if references 230.6.

In reading (c) however, why does it say "nearest the point of entrance of the conductors"? Why not just refer you to 230.6?

 

[kingpb]

I know that you're joking, but a lot of engineers do not appreciate being second guessed. No matter how politley you phase the question. I use to think we were all on the same team. I have come to realize that the engineer is the coach of the team, and you NEVER question a coach's decision.

If you really want to get them mad, offer some "value engineering" ideas to reduce your electrical bid once the initall budget come in too high.

What you may not be realizing when you provide "value engineering" is that the engineer may have already had countless meetings with the Owner and Architect, and proposed those same things, to no avail. Yes, engineers get testy, when Contractors come along, without having any history of the project, no insight into the relationships between the Architect, Owner and Engineer, no knowledge of financial or political drivers, etc, ... and offer "valued solutions". How do you know that value engineering hasn't already been done and the Owner has already accepted all that he is interested in.

As the Contractor you need to bid on the project given, and provide the work in accordance with the specifications, drawings, and NEC. If you want to create a good working environment, and you have some ideas that may help, then call the engineer, ask to meet and go over some things. Then you can point out some of the proposed cost savings measures and better get a read on how the engineer feels about it. This approach will work much better then issuing RFI's, or going straight to the Owner. No one likes to be backed into a corner.

Sorry, didn't mean to high-jack the topic, but since you mentioned it...........

 

[shockin]

WOW king, you seem passionate on the subject. The SOP around here is you bid on the project. The project comes in over budget - (always) - then the GC asks the subs to provide thier own alternates in order to get back under budget and make the project go. While you are correct that there may have been meeting between owners and designers prior, we generally see too little communication between the parties.

Where we seem to cause some tension is when we do suggest our alterantes, (value engineering) to the GC and the GC presents them to the owner and then the owner wants to know why the engineer was tring to sell them a porshe when all they wanted was a chevy in the first place.

For instance - instead of only using the Square D gear specified no sub - I'll send it out for a competative quote. Square D sees no sub in the spec and bids accordingly. The other mfgs bid competativly. I saved 12K the other day doing this. Is the customer getting a lesser product? IMO - No.

 

[zog]

For instance - instead of only using the Square D gear specified no sub - I'll send it out for a competative quote. Square D sees no sub in the spec and bids accordingly. The other mfgs bid competativly. I saved 12K the other day doing this. Is the customer getting a lesser product? IMO - No.

That depends on what you got. There are so many options on switchgear and ways to cut corners, chances are you got a $12,000 "lesser product"

 

[drbond24]

What you may not be realizing when you provide "value engineering" is that the engineer may have already had countless meetings with the Owner and Architect, and proposed those same things, to no avail. Yes, engineers get testy, when Contractors come along, without having any history of the project, no insight into the relationships between the Architect, Owner and Engineer, no knowledge of financial or political drivers, etc, ... and offer "valued solutions". How do you know that value engineering hasn't already been done and the Owner has already accepted all that he is interested in.

As the Contractor you need to bid on the project given, and provide the work in accordance with the specifications, drawings, and NEC. If you want to create a good working environment, and you have some ideas that may help, then call the engineer, ask to meet and go over some things. Then you can point out some of the proposed cost savings measures and better get a read on how the engineer feels about it. This approach will work much better then issuing RFI's, or going straight to the Owner. No one likes to be backed into a corner.

Kingpb, you are my new hero. I love you.

WOW king, you seem passionate on the subject. The SOP around here is you bid on the project. The project comes in over budget - (always) - then the GC asks the subs to provide thier own alternates in order to get back under budget and make the project go. While you are correct that there may have been meeting between owners and designers prior, we generally see too little communication between the parties.

Where we seem to cause some tension is when we do suggest our alterantes, (value engineering) to the GC and the GC presents them to the owner and then the owner wants to know why the engineer was tring to sell them a porshe when all they wanted was a chevy in the first place.

For instance - instead of only using the Square D gear specified no sub - I'll send it out for a competative quote. Square D sees no sub in the spec and bids accordingly. The other mfgs bid competativly. I saved 12K the other day doing this. Is the customer getting a lesser product? IMO - No.

Ok, now I know I'm making a bad thing worse but I'm going to do it anyway since that isn't really my intention.

What probably happened is that the engineer did their design exactly the way they did for a reason that they thought was a good reason. You come along and show the owner that there is a cheaper way to do it (there always is). The owner, most likely knowing nothing more about electrical stuff than how to turn on a light switch, gets mad at the engineer for costing him more money than necessary because he doesn't understand the reason the engineer did their design they way they did to begin with. The engineer ends up looking bad for no good reason and it is your fault (in my opinion), so the engineer is grouchy with you. I would be too. :smile: Then, a few years down the road when the cheaper stuff you suggested fails before it was supposed to, that is the engineers fault too since the as-built drawings show your idea and have the engineers name on them.

Just in case it isn't clear in the text, I'm not trying to start a fight. I'm smiling the whole time I'm typing this because I've been there. :grin: :grin:

 

[shockin]

chances are you got a $12,000 "lesser product"

Zog - Thanks for the responce. I understand what you're saying but I do have to disagree with you. In reviewing the proposals from the other mfgs I do not believe there is a differance in the BOM. If it was bid according to specs (other then no sub on the Sq D) there is no reason the BOM should be any different. I pretty much disagree any time I see "no sub" on drawings. To me that means the customer will not be getting the best price available for the project.

I do realize that at times there are very valid reasons for requiring only certain mfgs due to existing equipment ect. Most of the time I assume that a certain engineer just played a round a golf with a certain manufactures rep. Could be wrong - been wrong before.

 

[shockin]

Just in case it isn't clear in the text, I'm not trying to start a fight. I'm smiling the whole time I'm typing this because I've been there. :grin: :grin:

I'd be smiling to if I could figure out how to insert those darn things.

Thanks for the responce. I enjoy constructive arguments.

 

[charlie b]

I actually meet the requirements of (4) (a) so I didn't need to read down to (c) where if references 230.6.

Do you? Are the overcurrent devices (i.e., MCBs in the two panels) located outside the building?

In reading (c) however, why does it say "nearest the point of entrance of the conductors"? Why not just refer you to 230.6?

230.6 does not say anything about overcurrent protection or about disconnecting means. Rather, 230.6 gives you three options for considering a conductor to be outside a building. Any one will do. If you use one, then the disconnecting means (not the overcurrent device) must be located ?nearest the point of entrance of the conductors.?

 

[shockin]

Do you? Are the overcurrent devices (i.e., MCBs in the two panels) located outside the building?

I'm sorry - I meant (b) - The conduits run under the floor and then turn up into the panels. I believe that meets the definition of (Inside, nearest the point of entrance of the conductors.)

If you use one, then the disconnecting means (not the overcurrent device) must be located “nearest the point of entrance of the conductors.”

It makes much more sense when you explain it that way.

I still wonder why they would use two different terms in the same section. Outside - Outdoors. I took it to mean they did it on puprpose to keep the conductors outdoors. But it could very well be just a poor job of language selection by the NEC. That never happens does it?

I really do appreciate all your help.

(Edited to fix the quotations)

 

[brian john]

Somebody can always do it cheaper, less expensive and better seldom, but possible.

Cut acceptance testing
Al bus in lieu of copper
Use apprentices in lieu of mechanics.
cheaper products, substitutes.

You do not always need a Porches, but I would not want a Yugo either.

Myself I tend to be on the Porches end of things. I want to leave the BEST possible product behind. It is possible to do, profit margins may not be a high, but there is more to it than just the dollars FOR ME. My name means a lot.