What are your most common/frustrating design mistakes?

[ptrip]

I frequent these boards every day, trying to passively learn from other's questions and/or mistakes. I enjoy reading about the different things that everyone has experienced, be it contracting, designing or inspecting. I hope to learn from other's mistakes (as I've made more than my share at this point!)

I was reading a post just now: http://forums.mikeholt.com/showthread.php?t=120397

and this quote caught my eye

... Or make a little pamphet of common screw ups you're sick of talking about... (There are plenty of examples of conductor sizing, etc. to cut and paste from...) Then you wait for the reinspection fee...

I design the power and lighting distribution for commercial buildings, currently concentrating on schools (K-12 and university) and offices and such.

As a contractor: what are the things that leave you cussing at the designer? What things seem so simple to you that that person behind the "cushy desk" just can't seem to grasp?

As an inspector: what are the most common things you fail an install for? Are some of these things avoidable if dealt with on drawings first?

As a permit official: what are your most common correction comments?

I have a lot to learn ... and I'd rather not learn it all through change orders!

Thanks!

 

[cadpoint]

U asked!

U asked!

I design the power and lighting distribution for commercial buildings, currently concentrating on schools (K-12 and university) and offices and such.

As a contractor: what are the things that leave you cussing at the designer? What things seem so simple to you that that person behind the "cushy desk" just can't seem to grasp?

Where do you put the home runs on a circuit for multiply rooms?

Do you always put it to the closest point in respects to the panel?

Do you just run it to any light on the circuit for a clear presentation or do you bring it to the switch?

If you don't bring the power to the switch then your creating either a secondary wire or conduit back to switch or possibility creating a raceway in a light that is not rated for the service.

While it might be understood where to bring a branch circuit, some would say it is simple enough.
If the work is UL or quality inspected, its destracting to have to argue with an inspector why one did not follow the Spec's or drawing as shown.

Do you ever look at the HVAC plan and the sprinkler plan for the layouts in hallways for Grilles and head placements? Seems no one ever does.
Either one of two things happen everyones needs to be in the same space or there's no over head space to get by the HVAC main trunk in the hallway.

Then theres always seems to be some problem with a Grille to the smoke detectors...

 

[ivsenroute]

#1 problem with designs from architects and engineers:

Lack of compliance with section 505 of the IECC. Almost every single State in the Union has agreed to comply with energy requirements from the federal government and the IECC applies is most cases. In our state, it always applies. I reject more electrical drawings for this reason.

#2 on printed drawings: Not specifying conductor insulation and conduit type. Just labeling the drawings as #4 Cu in 3" conduit does not help me to do fill calculations.

 

[Joe Villani]

1. Referencing the adopted NEC cycle.
2. Energy Conservation Code issues. (Section 505)
3. Not providing demand calcs as per article 220, not just connected load.
4. Not showing rated walls and rated wall legends.
5. Not providing ul penetration details.
6. Non compliance to 210.8 (B) (1) thru (5).
7. Not showing disconnect switches/ breaker locks where needed.
8. Non compliance to 700.12 (F). (Local branch circuit).
9. 250.122 (B), (F) and (G).
10. 250.30 (A) (2).

I think of some more later.

Joe

 

[RICK NAPIER]

110.9 AIC calculations are almost never provided until requested and even then halve the time you need to explain it to the designers. And everything Joe listed.

 

[ptrip]

This is honestly great, folks, keep it coming.

I will most likely have to take some time to digest everything before I can come back with questions!

 

[elohr46]

I frequent these boards every day, trying to passively learn from other's questions and/or mistakes. I enjoy reading about the different things that everyone has experienced, be it contracting, designing or inspecting. I hope to learn from other's mistakes (as I've made more than my share at this point!)

I was reading a post just now: http://forums.mikeholt.com/showthread.php?t=120397

and this quote caught my eye



I design the power and lighting distribution for commercial buildings, currently concentrating on schools (K-12 and university) and offices and such.

As a contractor: what are the things that leave you cussing at the designer? What things seem so simple to you that that person behind the "cushy desk" just can't seem to grasp?

As an inspector: what are the most common things you fail an install for? Are some of these things avoidable if dealt with on drawings first?

As a permit official: what are your most common correction comments?

I have a lot to learn ... and I'd rather not learn it all through change orders!

Thanks!

During my 37 years of working mostly from engineered drawings we didn't see that many problems. We got paid to put it in, paid to take it out or paid to fix it. I don't have any complaints at all, some things just can't be avoided.

 

[steve66]

I have a job checklist I usually try to run through before I send out a set of drawings. A few things to check:

1. Did the legend get put on the drawings? (I don't think I have ever sent out a set without one, but I frequently don't notice we don't have a legend until the project is almost complete.)
2. Running 500 kcm wire from a transfromer to a 400 A breaker. Or (2) sets from a transformer to a 800 A breaker. Or (3) sets to any 1200 amp breaker.
3. Not getting two emergency lamps over the exterior doors.
4. Architects like to flip the door swings at the last minute, and not tell anyone. Guess whose fault it is when the light switches wind up behind the doors.
5. Always show doors on the lighting plan (see number 4 above).
6. Make sure an important layer isn't turned off at the last minute. (ie: drawings go out without any smoke detectors shown).
7. I always make a note to field verify any equipment requirements. There are frequently minor changes in their requirements that nobody can know about until long after the drawigns are out.
8. I always make a note to coordiinate all outlet locations. Things get changed (even after the drawings go out), and I always get blamed when the contractor puts an outlet behind a cabinet.

Steve

 

[kc8dxx]

Not in any particular order:

1. Conduit fill and conductor derating.
2. Arc Flash/Short Circuit Current Rating.
3. Not using devices within the manufacturer's specifications, especially supplementary OCPD's.
4. Grounding of cabinets downstream of an isolation transformer.
5. Conductors undersized per the upstream fuse.
6. Lack of OCPD co-ordination.

...and my personal pet peeve of the week...

7. Not reading the manufacturer's manual until after the design was completed and their product is sitting on the shop floor.

 

[nakulak]

the last couple of retail (mall) stores incorporated current limiting subpanels for energy saving on track lights, and the designs were flawed (in a major way).

 

[e57]

I frequent these boards every day, trying to passively learn from other's questions and/or mistakes. I enjoy reading about the different things that everyone has experienced, be it contracting, designing or inspecting. I hope to learn from other's mistakes (as I've made more than my share at this point!)

I was reading a post just now: http://forums.mikeholt.com/showthread.php?t=120397

and this quote caught my eye



I design the power and lighting distribution for commercial buildings, currently concentrating on schools (K-12 and university) and offices and such.

As a contractor: what are the things that leave you cussing at the designer? What things seem so simple to you that that person behind the "cushy desk" just can't seem to grasp?
~~~~~~~~~~
Thanks!

In that post - which I self-edited, because the sentence you posted covered my point, I had originally had a link to an EC&M article. And originally had a bit about Just In Time education... Something a friend of mine had worked on with Phoenix University - where companies could devise SOP's and common technical training into a book - or hand out for particular situations... Example: The plane that landed in the Hudson, both pilots had a flip-chart that they went through at the out-set of that... They flip to "Engine Failure" - skip to "Multiple Engine Failure" then they had to go through a check list of things to do... (All of which didn't work...)

I used to work for a guy who was friends with the guy who started doing these.... Which for a lack of a better word are limited in scope - and embarrassingly simple - some of them are in cartoons... But - they get the major points across - and reference where to find more info.... Great - but there are so many more subtleties.... BUT - any EC should be able to WRITE one of those - not RELY ON IT!!!!

Years ago SF had an exceptionally rude - inhuman inspector (who was the son of the chief inspector...) He would show up at jobs and just throw out chits of paper with code section numbers on them and leave.... (Many of them were irrelevant anyway... He was just flaunting power...)

But if there was a link or relevant information on it - there would no need to explain what was meant by the code reference - that would be both helpful to the inspector - by not having to constantly explain the code, and to the EC who should have known better what was misunderstood.
Example: In that thread an EC mis-sized NM for a hot tub - you pull out a piece of paper for 334.80 with an example right under it. This article doesn't cover NM specifically - it skips the extra step because of 334.80 - but is a good example of conductor sizing...

I used to give guys short classes on site for specific stuff I wanted to do in specific ways. Some of them with hand-outs... Some pretty detailed... But it doesn't need to be that long.... If an inspector - on top of failing and provided a code reference gave an example of that code correctly used - it might save a lot of hassle for the second inspection... (WHICH IS NOT HIS JOB! BTW...) But if he had a piece of paper that said this:

334.80 Violation - Ampacity selection of NM cable
Common mistake is that the 90 degree column of T310.16 is ONLY allowed to be used for derating purposes - so long as it is not greater than the 60 degree value.

An example: #8/3 NM cable is rated for 40A unless otherwise derated by bundling >24", or multiple cable through fire/draft stopped penetrations.

Please make appropriate corrections and call for re-inspection.

Thank you....

That said - I'm sick of explaining residential required receptacle spacing to Architects - often the same ones - because they don't want to know.... Or explaining title-24 over and over again.... Whats worse is I often have to explain it to "Electrical Consultants" that these dopes hire... They should be explaining it to me for what they are paid...

 

[e57]

I have a job checklist I usually try to run through before I send out a set of drawings. A few things to check:

1. Did the legend get put on the drawings? (I don't think I have ever sent out a set without one, but I frequently don't notice we don't have a legend until the project is almost complete.)
2. Running 500 kcm wire from a transfromer to a 400 A breaker. Or (2) sets from a transformer to a 800 A breaker. Or (3) sets to any 1200 amp breaker.
3. Not getting two emergency lamps over the exterior doors.
4. Architects like to flip the door swings at the last minute, and not tell anyone. Guess whose fault it is when the light switches wind up behind the doors.
5. Always show doors on the lighting plan (see number 4 above).
6. Make sure an important layer isn't turned off at the last minute. (ie: drawings go out without any smoke detectors shown).
7. I always make a note to field verify any equipment requirements. There are frequently minor changes in their requirements that nobody can know about until long after the drawigns are out.
8. I always make a note to coordiinate all outlet locations. Things get changed (even after the drawings go out), and I always get blamed when the contractor puts an outlet behind a cabinet.

Steve

I think many of use would love you to add to the list:
Coordinate lighting locations with mechanical ducting and fire-sprinkler RCP...

 

[MNWildcat]

I think many of use would love you to add to the list:
Coordinate lighting locations with mechanical ducting and fire-sprinkler RCP...

I agree with this one. I am very diligent with coordinating ceiling device locations, especially since smoke detectors and HVAC diffusers do not play well together - this can greatly affect their layout.
But the problem is that many times the fire suppression system is usually performance speced and therefore there are not any drawings to coordinate with since they are done after the bids are awarded. Then the fire suppression contractor is the first one to install and puts his stuff right where all the other stuff was already coordinated. This applies to above ceiling spaces as well.

 

[cowboyjwc]

From a plan checkers stand point I had one today.

Guy resubmits some plans with some existing clouds on them and said we're adding a couple of outlets. No new clouds, I pull out the old plans and he's adding 20 outlets and a new panel and a piece of equipment. No letter of explaination, no clouds, just me having to go through sheet by sheet and compare them.

I also don't like when things are called out for on the plans, but nothing in the legend matches the picture.

And I write more corrections on custom homes then anything else and it's usually required stuff.

And the rated wall thing that someone else mentioned.

 

[scott thompson]

My "Pre-Plancheck Submit" check lists are now spanning over 12 pages!!!

For a more effective approach, I have gone a new direction: PDF Check Plots, checked by a "Reviewer", criteria per a Project checklist.

This has been a much more efficient technique overall.

Since I could look at the Plan Set Sheets endlessly and only catch <20% of any possible errors / issues, having another Person review the Set prior to P/C submit is the best method for me.

The Reviewer checks over the complete Set - as PDFs instead of hard copies.
The review set is Plotted as PDFs - so as to reduce the Paper usage and for a better workspace (we use large flat panel monitors).

With the PDF Plots, are a series of "Project Design Criteria" documents, which were compiled as part of the Proposal's Scope of Work.
The SOW listings for design criteria have been compiled with design / engineering parameters, so each item is simply a selected text string, with user edit fields for specific information.
These "Lists" of selections compose the D&E Spreadsheet (Excel Workbook).

Any Change Orders and other revisions are appended to this Spreadsheet per relevance.

In addition to the Project Specific listings, there are "common items" which are defaults for all Plan Sets.

The Reviewer compares the criteria listed in the Spreadsheet, to the data listed on the E Sheets. Reviewer also looks for Drafting issues - such as Blocks being "Orphaned", line and text scaling issues, and similar stuff.
(I want the printed documents to look as professional as possible).

When the Reviewer finds an error, a Comment Text Box is attached to the PDF file (using Adobe Acrobat Standard versions 5 thru 9).
After the entire Set has been checked, the PDF Set is sent back to me for "Cleanup".

I first save the "Pre-Edit" Sheets as new files (for redundancy), then edit the ACAD files as necessary.
The Reviewer's initials are entered into the Title Block, at the "Checked By" field.

There are a lot more routines involved with our Plan Sets, but this covers the Pre - P/C submission review tasks.

Scott

 

[cowboyjwc]

Oh and I forgot, "red marks on the plans are never a suggestion."

 

[nhfire77]

"My plans fit, you have to make it work, I'm right..."

I would not call and bother an engineer, until I am sure that I cannot put the device 20' AFF on the wall that is 8' high.

We all make mistakes, but, I've been told by more than one project engineer/designer, that "MY PLANS" are right.

(begin sarcastic attitude) "OK OK, you drew them, they are your plans, I just connect the dots and color between the lines but I will not violate the laws of physics for you." (end sarcasm)



I reserve the miracle biz for the AHJ, to override you and change something at the final walk through that was on the approved plans, but it has to be changed, or I don't pass inspection.

 

[sparky=t]

there are alot of issues i have dealt with in the past with engineers and artichokes, most of them have been mentioned in previous replies. since i have been doing design build work i have noticed that lack of information from mechanical contractors, sprinkler contractors and general contractors leave alot to be desired.. you complete a job on supplied cad file and get to the job to find out they changed rtu manufacture and your ocp is wrong, gear is on job, walls you were going to mount panels on are no longer part of the job. I can relate to desiners and engineers fustrations at times as well as installers!

 

[ohmhead]

Well we need to look at the size of electrical rooms there getting smaller !


Just once i would like a electrical engineer to give me a chase or riser in a building shown on the drawnings .

How about you figure out each conduit to and from on that riser one line and tell me how and where to run each and every feeder at what depth elevation to avoid structual and mechcanical underground conflicts .


Also do it for all the overhead in building put into a bim cad 3d drawning and will use that to coornate with other contractors.

Oh come to all the coornation meetings and just listen once!

How about answering a RFI in a week!

And give me a solution !

Never change anything !

 

[don_resqcapt19]

...

We all make mistakes, but, I've been told by more than one project engineer/designer, that "MY PLANS" are right. ...

i was doing a food store a long time ago with an engineer like that. I had found a few small issues that needed to be changed and the engineer was giving me a lot a grief about it...so when I found a big issue later, I just ignored it. There was no power called out for the compressor rack. It was a very expensive change order that would have been about half as much if the engineer had been reasonable about the little things I had found earlier in the job. (the cost difference was a result of the increased labor to install the feeder with the store almost complete)
The job goes a lot smoother when both the contractors and the engineers are working with each other.