MCC shop drawing submittals

[t_van]

I've been working for a city municipal utility for about 6 months now. I'm the electrical engineer and am responsible for ensuring the consulting engineer's design is in conformance with the NEC and our local specs and standards. I came from the private industry where I didn't have the tasks of reviewing shop drawings and therefor have minimal experience in reviewing shop drawings. I am beginning to review shop drawing submittals for MCCs that are to be used in a process air blower project. The MCC submittals are some of the first shop drawings I am reviewing from a manufacturer. During my review, I am seeing that a lot of product information is either missing or incorrect from what is stated on the PLANS. My question is, is it normal for manufacturer's first revision of a submittal to purposely exclude or misstate product information because they know the contractor is overall responsible for the accuracy in the submittals and the consulting engineer will comment on corrections which in turn makes the manufacturer's job of getting the correct information on the shop drawings? Just a thought. I don't understand how shop drawings can be missing so many items and features contained in the conformed set that was given to the manufacturer. Is this a common practice for manufacturers to leave it to the consulting engineer and contractor to comment what is exactly needed in the submittal? Seems like this approach from the manufacturer could ease the amount of time they spend looking at the PLANS and specs. Maybe I'm reading into this too much.

 

[Besoeker]

I've been working for a city municipal utility for about 6 months now. I'm the electrical engineer and am responsible for ensuring the consulting engineer's design is in conformance with the NEC and our local specs and standards. I came from the private industry where I didn't have the tasks of reviewing shop drawings and therefor have minimal experience in reviewing shop drawings. I am beginning to review shop drawing submittals for MCCs that are to be used in a process air blower project. The MCC submittals are some of the first shop drawings I am reviewing from a manufacturer. During my review, I am seeing that a lot of product information is either missing or incorrect from what is stated on the PLANS. My question is, is it normal for manufacturer's first revision of a submittal to purposely exclude or misstate product information because they know the contractor is overall responsible for the accuracy in the submittals and the consulting engineer will comment on corrections which in turn makes the manufacturer's job of getting the correct information on the shop drawings? Just a thought. I don't understand how shop drawings can be missing so many items and features contained in the conformed set that was given to the manufacturer. Is this a common practice for manufacturers to leave it to the consulting engineer and contractor to comment what is exactly needed in the submittal? Seems like this approach from the manufacturer could ease the amount of time they spend looking at the PLANS and specs. Maybe I'm reading into this too much.

My background is from the manufacturing end. I do not think the manufacturer would intentionally produce drawings with errors or omissions. Every drawing revision takes time and thus has an attendant cost which likely will have to borne by the manufacturer.

That said, some consultants can be a right pain in the backside. One of my guys commented once that, on his next project, he was going to blank drawing sheets because everything would get changed anyway.......

And just a thought about the format of posts. A few paragraph marks can make it easier to read.

 

[mpoulton]

That doesn't sound normal to me. Didn't the contractor have to review and approve the shop drawings before they got to you? Why didn't they catch the problems? Sounds like the approval process isn't working. In my experience, the drawings should be pretty much perfect by the time they make it to your desk. The preliminary stuff should be handled between the GC, subcontractors, and equipment suppliers.

 

[smoothops10]

MCC mfrs do not like to customize. They want to supply the MCC. They try not to take on an integrator or panel shop role. I'll often see the first submittal with ladder diagrams for each compartment straight out of their catalog with no or very limited modification for the project specific requirements. Things like a remote start/stop pushbutton control station or HOA will often be missed. Hopefully your engineer commented on these missing items. If not, then yes I think you should point out the things missing and have the engineer comment accordingly.

In the future consider having the engineer write the contract for the MCC to be supplied by the integrator instead of the electrician. Often times the mfr like Allen Bradley, SqD, Eaton will supply a bare bones MCC to be customized by the integrator's UL shop and they generally do a better job of tying everything together and supplying custom wiring drawings for each compartment then the MCC mfr who is just trying to supply an MCC.

 

[Jraef]

It's hard to comment not knowing what's missing, but I'll offer common issues I see.

When building an MCC to UL845, each "bucket" assembly is individually tested and listed in the exact format it will need to be used with. So what seems to happen a lot is that an EE will show a specific size of MCP used on a starter, but when the shop drawings come out, they show the size of MCP that starter is UL listed with, and that cannot change, so to the EE, it looks like a deviation.

Another possibility has to do with the fact that with public agency purchases, it usually must be awarded to the low bidder. That often results in the order going to the supplier or contractor who made the biggest mistake. With MCCs, that can mean that someone ordered the MCC in a "Class" that is lower than intended. These classes, I and II, along with types, A, B, and C, define not only how the units are built and wired, but also what the MCC mfr provides as documentation. A really common aspect that happens is that the EE intends to get a Class IIB, which shows all interwiring between units AND external circuits, but the low bidder bid it to the contractor as Class IB, which is only the unit wiring and is cheaper, expecting the contractor or a systems integrator to finish it.

 

[petersonra]

You also have to take into consideration that most of the time you pretty much get generic drawings from MCC makers with the exact information for a specific bucket found only in a list somewhere.

I have seen MCC drawings that showed a single schematic where there are dozens of buckets and then there is a list somewhere that says what is actually in each bucket.

Sometimes you get a schematic that seems to have every possible option shown in it and a list that tells you what you actually got.

Sometimes it seems random what you get as far as drawings go.

I remember one time getting no drawings at all. Just a booklet that seemed to have every possible configuration the MCC came with in it and then a list that said what was actually supplied in each bucket.

OTOH, I have also seen them come in with an individual drawing for each bucket in the bucket.

I got one the other day where the MCC has 5 or 6 buckets. All but one are for motors, and one is for a heater. The heater is not supposed to have an overload relay but the two bucket drawings supplied by Square D are identical. There things are also supposed to have an extra set of overload relay and contactor aux contacts. The drawing I got does show two sets of extra aux contacts but no indication if they are for the contactor or the overload relay or one set for each.

 

[Jraef]

You also have to take into consideration that most of the time you pretty much get generic drawings from MCC makers with the exact information for a specific bucket found only in a list somewhere.

I have seen MCC drawings that showed a single schematic where there are dozens of buckets and then there is a list somewhere that says what is actually in each bucket.

Sometimes you get a schematic that seems to have every possible option shown in it and a list that tells you what you actually got.

...

So in the NEMA MCC "Class" definitions, this is the difference between Class II and Class IIS. Straight Class II means the MCC mfr will supply the standard drawings with either specific modifications, or more typically, a reference sheet as Bob described. Class IIS would be that each and every bucket has it's own customized drawing specific to that bucket only and done to a specific drawing/design standard laid out by the specifying engineer. As you might imagine, this is basically the most expensive option, because it cannot be automated.

A lot of people are unaware of this, because it was something NEMA added years later (not sure when) so when people got training a long time ago, they never got the message. So again, an EE calls out Class II type B in the boilerplate spec, but was expecting what is now called Class IIS type B and is disappointed.

 

[petersonra]

So in the NEMA MCC "Class" definitions, this is the difference between Class II and Class IIS. Straight Class II means the MCC mfr will supply the standard drawings with either specific modifications, or more typically, a reference sheet as Bob described. Class IIS would be that each and every bucket has it's own customized drawing specific to that bucket only and done to a specific drawing/design standard laid out by the specifying engineer. As you might imagine, this is basically the most expensive option, because it cannot be automated.

A lot of people are unaware of this, because it was something NEMA added years later (not sure when) so when people got training a long time ago, they never got the message. So again, an EE calls out Class II type B in the boilerplate spec, but was expecting what is now called Class IIS type B and is disappointed.

Hmm. never heard this before.

 

[Jraef]

Hmm. never heard this before.

Yeah, you and probably 90% of the rest of the EE world. I hadn't heard it when I got back into doing MCCs in 97, but it hadn't happened when I dealt with them up until 88 when I left Square D. So it happened some time between 88 and 97.

No, wait. I still hadn't spec'd or bought an MCC until I went to Siemens in 2005, so between 88 and 05.

PS: A little sleuthing through NEMA looks as though it may have changed in 2001 with the move from having MCCs be buried in the general "Industrial Control Systems" spec, NEMA ICS-3-1993 where it was under "factory assemblies", to having it's own separate standard, NEMA ICS-18-2001.

If anyone is interested in reading it, it's free from NEMA if you just register your email. They will spam you a little, but you can opt out afterward.

https://www.nema.org/standards/pages/motor-control-centers.aspx?#download

 

[Ingenieur]

Unusual that a bid set for a waste water project has detailed info on the mcc
usually a standard of quality spec and a schedule of buckets
voltage, bus size, etc
hp, control type, etc for each bucket

what do you think is missing? give us some examples please
does the mfg differ? This is public money so open bid usually
does it conform to the basics
number of starters
hp's
metering if req
control methods
etc

I review for functional equvilency, not tit for tat identical conformance

your review does not relieve the contractor from complying and providing a functional system suitable for the intended purpose

you are REVIEWING it NOT APPROVING it
you will ACCEPT the whole project after testing/inspection

a meeting with the consulting engineer, submitting contractor and mcc vendor to review and ssk questions may help you understand the process

Contractors/vendors imho seldom are trying to 'pull one over on you'
they have done this 100's of times and want to do a good job just like you
they want in and out and paid with the least amount of issues and warranty/trouble calls so they can move on to the next project while keeping you happy for the next time you work together
they want a good outcome and reference

bad apples are rare

 

[Fitzdrew516]

I review for functional equvilency, not tit for tat identical conformance

your review does not relieve the contractor from complying and providing a functional system suitable for the intended purpose

you are REVIEWING it NOT APPROVING it
you will ACCEPT the whole project after testing/inspection

Could not agree with this more. I have never "approved" a submittal. At best it's "No exceptions noted".