Selective Coordination Study

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ncwirenut

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I am currently on a project that is requiring a coordination study. The gear manufacturer has quoted me a minimum of $7,000.00 to do the study. I have looked at the software to do it myself and looks like that is the better deal. Any recommendations on the software or should I stay away and pay the manufacturer.
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
Just buying the software will not resolve your situation. You might check the project requirements more carefully. If they want a calculation, such as the selective coordination study, then they are likely to require it to be prepared under the supervision of a licensed professional engineer. This is not something you can do on your own, and send the final results to the engineer for a review and approval. The engineer has to be involved early enough in the calculation process to be able to assert that he or she had supervised the work.
 

bphgravity

Senior Member
Location
Florida
I agree with Charlie.

For example, here in Florida, an engineer is required to design the electrical system for any service 800A or greater; including selective corrdination. We will typically be looking for a comprehensive fault analysis and applicable time/trip curves for installed overcurrent devices and equipment.

The engineer of record would be required to verify and affirm any data and analysis provided to tem by a manufacturer and the utility provider.
 

zog

Senior Member
Location
Charlotte, NC
I am currently on a project that is requiring a coordination study. The gear manufacturer has quoted me a minimum of $7,000.00 to do the study. I have looked at the software to do it myself and looks like that is the better deal. Any recommendations on the software or should I stay away and pay the manufacturer.

There are plenty of 3rd party engineering firms that can do this for you, put it out for bid, the OEM's sre usually pretty high on these.
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
We do that sort of consulting work. Here (just off the top of my head) are a few factors that will influence the cost. It starts with the question of whether this is a new construction project or a renovation of an existing building.

Issues specifically related to renovation projects.
? Is there an accurate and reliable set of riser diagrams and panel schedules? A field trip to verify existing conditions would have to be part of the cost in any event.
? Is there an accurate and reliable set of floor plan drawings that can be used to estimate the lengths of feeders and branch circuits?
? Is there an accurate and reliable list of equipment (i.e., panel types and ratings, as well as motors and their HP ratings)?
? Is there an accurate and reliable list breaker trip settings? A field trip to gather this information would have a significant cost.

Issues that are common to renovation and new construction projects:
? Has the contract for equipment supply been awarded (i.e., has the manufacturer of the equipment been selected)?
? How many buses (i.e., switchboards and panels) are included in the design?
? Is there a backup generator?
? Does the requirement for coordination apply only to the emergency and legally required standby systems, or to the normal power system as well?
? Does the requirement for coordination apply only when the utility (i.e., normal) power source is lost?
? Does the requirement for coordination apply in a breaker?s instantaneous trip range?
? Is the coordination study being performed in conjunction with a short circuit study?
? Is the coordination study being performed in conjunction with an arc flash study?
 

ncwirenut

Member
It is a nursing home with 35 panels and a 500kw generator. It has three ATS, it is new construction and the plans are pretty good. The only requirement is that we meet the 2008 NEC requirements for selective coordination and that's all it says. Based on what Charlies said, maybe the quote isn't that bad.
 

charlie b

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Location
Lockport, IL
Occupation
Retired Electrical Engineer
You do need to get a clearer understanding of what you will be getting for the price. In order to ensure coordination between, for example, a branch panel's feeder breaker (on the distribution panel upstream) and a branch circuit breaker, all you need to know is the choice of breaker models and their settings. You overlay the two curves, and you can verify coordination. That is not a complicated or expensive process. The manufacturer will have done it many times before, and they already know what breaker types they will be using.

Different from this would be a short circuit or arc flash study. Those require you to provide much more information (i.e., into the computer model). This includes every feeder size and length, every transformer's ratings, every panel's short circuit rating, and every breaker setting. This makes for a more complex, and more expensive, calculation process.

So if you need to be able to prove that every one of the 35 panels has a short circuit rating that is higher than the amount of short circuit current available at its location, you won't get that with just a coordination study. And if you need to provide arc flash labels, you won't get that with a coordination study either.

So once again, I would suggest reviewing the manufacturer's proposed work scope, and make sure you are getting everything that you need for the price.
 

spikes2020

Member
Location
Nashville, TN
We use E-Tap http://etap.com/ software and it is very good, but $7,000 sounds like a good deal considering that is the price that you will need to spend just to get one module of this software, not including the time running it.

For good software like this you will pay extra but you can do arc-flash and load balancing almost everything you could ever want. Many power plants now use it to do live calculations and such.

But like they said we always get an outside consultant to at least double check our numbers, so they share or take the risk. If some one dies due to your miss calculations you don't have the insurance for that.
 

tkb

Senior Member
Location
MA
I have been involved with a few of these and did the leg work for the engineer.

That meant getting a feeder list with wire sizes and conduit type with the lengths.
If you can eliminate the engineers field trip, you can save money on this.
 

skeshesh

Senior Member
Location
Los Angeles, Ca
I have been involved with a few of these and did the leg work for the engineer.

That meant getting a feeder list with wire sizes and conduit type with the lengths.
If you can eliminate the engineers field trip, you can save money on this.

In this projects I've been involved in this has been the approach. Healthcare facilities, school campuses, military and such often have facility electricians who are well qualified to gather this information and frankly much more familiar with the campus layout.

Charlie pointed out a good consideration regarding what is actually required in the power system study.

As far as softwares check the clients requirement. I've only seen ETAP and SKM specified and have used both - I wouldnt say one has a clear advantage over another. I believe SKM is a bit cheaper but not significantly so and it delivers just as well as ETAP. It does not sound like you should be buying any software though. Look around and you may find someone to do it for you for a great price - I know of semi-retired engineers who pretty much work out of home and do not want to squint over lighting or receptacle trivial stuff and do only power study work and often have very competitive rates.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
Warning personal rant - not directed at OP

Warning personal rant - not directed at OP

I am amazed at how much bashing goes on when it comes to DIY and 'cut-rate' electricians, but a pass is given to DIY engineering. Remember, there is a reason why trained and licensed specialists exist.

Now to the OP,
Hard to tell if your $7K price is good or bad, but it seems pretty reasonable.
'Article 700' selective coordination is often much more complicated than simple matching one device curve to another. Many times a preliminary report is required before equipment is ordered, this report version usually includes recommended equipment and design changes to meet .01s coordination. A final 'as-installed' report is usually specified.
 

tkb

Senior Member
Location
MA
Around here we can engineer our own jobs as long as we are doing them.
We cannot design for hire.

Some customers require a stamp though.
 

skeshesh

Senior Member
Location
Los Angeles, Ca
It does depend on the scope of work and the type of facility too.

I'm certainly not questioning Tim's qualification but there are clients who require and will never accept any power system study including selective coordination that's not been conducted by a licensed engineer (a qualified one at that who can demonstrate certain numbers of projects and years of performing coordination). I guess it is possible that an engineer will be willing to rubber stamp coordination that you've done on your own but that's a different issue altogether...
 

tkb

Senior Member
Location
MA
Just like I can do my own home wiring but, just because I can, doesn't mean I should.

I never said I would do a coordination study, only gather the information.
I only meant that we could do some designing and simple engineering if we are doing the job.

Don't worry, your cushy engineering jobs are not in jeopardy by us DIY electrical contractors.
 
I am currently on a project that is requiring a coordination study. The gear manufacturer has quoted me a minimum of $7,000.00 to do the study. I have looked at the software to do it myself and looks like that is the better deal. Any recommendations on the software or should I stay away and pay the manufacturer.

I am a licensed professional engineer who often comes to this website to learn thing or two. I am not trying to sell you a service, but our company has done various coordination study for healthcare, including some in the state of Florida, as per NEC requirement.
I don't know how much our company charges for this service but if you are interested, I can find that out from our chief electrical engineer.

[Moderators Note: E-mail address removed, if you wish to contact this member please use the P.M. feature]
 
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I believe, as per the forum rules, I can't give you my email address. But if you are interested, please {Moderator's Note: Company name and location have been deleted. Like Raider1 already said, use the Private Message feature, if you wish to contact any other member on this forum}.
 
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Mike01

Senior Member
Location
MidWest
2008 Requirement

2008 Requirement

The selective coordination to meet the 2008 NEC will only apply to the life safety systems of this project. I believe the NEC olny requries the life safety system to be coordinated so it would not be all 35 panels just the isolated life safety path. Be sure to look at both normal and emergency "modes" of operation if required. Just my 2 cents.

It is a nursing home with 35 panels and a 500kw generator. It has three ATS, it is new construction and the plans are pretty good. The only requirement is that we meet the 2008 NEC requirements for selective coordination and that's all it says. Based on what Charlies said, maybe the quote isn't that bad.
 

necnotevenclose

Senior Member
$7k sounds like a pretty good price to me. If you purchase you have to look at software cost, subsrciption cost, time...lots of time to not only build the one-line and TCC curves, coordinating OCPD issues and creating your presentation.

Having your gear vendor provide a stamped & signed coordination study in the end will probably save you time, money & sanity.
 
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