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200% rated neutral?

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Discussion starter · #23 ·
Paulusgnome said:
I don't suppose it is possible to actually ask the engineer for a sanity check on this? It does sound like the fat neutral is a bit redundant but there may be a reason.
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Nah he was instantly on the defense when I mentioned the increased rating. I think like Signal1 said he was burnt in the past and its a CYA thing.
 
Discussion starter · #24 ·
RePhase277 said:
What is the neutral for? Why is it there if this panelboard is for motor drives? Are there any single phase loads coming out of it?
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I have no idea. No single phase loads and no space for future expansion.

telsa said:
While the OP phrased the issue as engineering... the play has to be politics.

About which, we here, commenting, are totally in the blind.

It would appear that the OP is a co-EE on this project.

That's weird, right there.

It smells like the EE is not being paid well... used 'old work' -- again... and punched his craft out the door.

The OP appears to have a patron that has a Very Big Budget... but wants to make the nickels bleed.

So the patron spends 'nothing' on the EE and gets back a canned solution.

For a neutral -- at all -- smells of a canned solution.
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Yup sticky situation for sure, I was originally hired by the architect to review the electrical drawings and provide any relevant corrections. There was a ton of corrections, phone calls between the architect, EE and me by the end of which I think the EE was pissed. Next was to provide a spread sheet for the electrician that denoted what size, type, quantity and connection type was needed for the owner supplied equipment. Also to provide a rough design and load calcs for an ICP. The ICP was to have 47 ATL combo motor starters, 120 & 24 vac control,14 interposing relays, 96 function relay logic board. Then they added interviewing the electrical contractors bidding on the job, reviewing VE, and site inspections periodically. Next they wanted me to build an ICP that included 29 vfds, ocpd for each vfd, filters, 16 ATL combo motor starters, two control transformers, 56 interposing relays, 96 function relay logic board. After kicking around the design, I suggested the removal of vfds/filters from the ICP. They still wanted the OCPD's to be located in the ICP to avoid having add additional panels/breakers but after some review a separate panel board was a no brainer. I think it was the EE that either recommended using VFDs in place of the ATL starters or signed off on the idea but I don't think he realized the size or cost of an ICP with that many vfd's. The heat load alone would be intense probably unmanageable considering they allotted space for a 120"w X 90"t X 24"d enclosure. I can't remember all the sizes but it was something like 2-40hp, 2-20hp, 15-10hp, 10-15hp vcd's with filters. Long story short I think I probably caused a headache for the EE and now he's returning the favor.
 
#27 · (Edited)
cdslotz said:
of course he is.....you're questioning his design....duh!
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What you have to watch out for is a budding EE who's getting his marching orders from above -- a canned solution -- and you're making him look stupid -- during his early daze on the job.

I well remember a budding EE who was delirious that my actual build of his cluster looked like a dream.

He was so proud, his second project, that many a photo was taken, by me, of him, and his executed project. The changes involved were rather remarkable, BTW.

It went from an L cluster to a clean, straight line up... much cheaper and quicker to build.

He was so gobsmacked that he ran around like a kid Christmas morning... taking no end of his own ( official ) photos for his portfolio.

His next work required a miracle worker -- me -- to get the job done. Don't blame him. Blame the architect. He came up with a dream building that lacked any provision for its feeders. They had to jump from floor to floor -- without any 'window.' That was charming.

The super was semi-astounded that I could even get them in the building. They were jumping all over the place. [ left, right, over, and back ]
 
#28 ·
Some architects & engineers need to have their wings clipped. Reminds me of the draft drawings that don't exist in reality (they're optical illusions).
 
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#29 ·
RePhase277 said:
Sheesh... I think it's a no-brainer then. If this panel is full, and there are no single phase loads of any sort, there is no need for a neutral, let alone a super neutral.
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Well, that's enlightening info we weren't presented with by the first post...so yeah, completely different scenario.

Unless you have sub-feed lugs and the EE has plans to allow for that in the future, and is making the neutral available...though I seriously doubt the EE is seeing that far ahead.
 
Discussion starter · #30 ·
cuba_pete said:
Well, that's enlightening info we weren't presented with by the first post...so yeah, completely different scenario.

Unless you have sub-feed lugs and the EE has plans to allow for that in the future, and is making the neutral available...though I seriously doubt the EE is seeing that far ahead.
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Would this info have changed your original answer?
 
Discussion starter · #32 ·
cuba_pete said:
Yup.

#24 was a lengthy bit of additional info.
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True but either way would you be willing to take liability for VE'ing a 100% neutral?

I feel like even know I'm knowledgeable, have years real life experience, a licensed master electrician and have 1 million in liability coverage, I would be hesitate to accept liability for VE in this case. I think if it came down to a legal battle my calculations when compared to those done by a licensed PEE wouldn't mean very much and I would be left holding the bag.
 
#33 ·
tates1882 said:
True but either way would you be willing to take liability for VE'ing a 100% neutral?

I feel like even know I'm knowledgeable, have years real life experience, a licensed master electrician and have 1 million in liability coverage, I would be hesitate to accept liability for VE in this case. I think if it came down to a legal battle my calculations when compared to those done by a licensed PEE wouldn't mean very much and I would be left holding the bag.
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His calculations and yours would be the same: 0 amps.
 
#34 · (Edited)
#35 ·
cuba_pete said:
Yeah, what he said. ^^^

If the neutral isn't/will not be used by any load (and if it were up to me entirely) then there is absolutely no reason for pulling it to a panel. It does nothing.

I googled a thread for you from other knowledgeable types of yore.
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It the same way with me and AFAIK .,, any panel without neutral is not being used I would not bother pull it there.

I am sure I did mention it before just put a sign to warn any other wannabe dolts that there is no netural in there. ( ya some inspectors do approve this methold as well )
 
Discussion starter · #36 ·
Well the plot thickens! I asked for the AFC at the breaker feeding the panel in question, the engineer won't give an AFC value but did say the panel would need to be 65kAIC rated. Now the AFC provided by the Pco was 30000 amps, its what the EE has on the prints, and its what all the suppliers used for designing AIC ratings on panels. The EE has right on his prints on the one line showing the service main an kAIC rating for the main breaker as 42kAIC. WTF.
 
#37 ·
Trust me, there are a LOT of EEs out there, including those with PE licenses, that know virtually nothing about harmonics, and it scares the bejeebus out of them. So rather than pay attention and learn, they just throw money at things, usually OTHER people's money, to over build equipment. I just did a seminar on harmonic mitigation for VFDs last week, several of the attendees were PEs, who I would have though didn't need to attend. One of them had a difficult time with me telling him that triplen harmonics are not a thing with VFDs (unless fed with a single phase source). I had to go over that several times. He was probably a guy that has been specifying 200% neutrals on 3 phase panels and MCCs that are feeding VFDs.

Now, that said, the 200% neutral IS a good idea on a 480/277V panel that is feeding 277V LIGHTING ballasts, because now they are ALL non-linear loads and create triplen harmonics. So to the earlier points, if he is thinking that by it's mere existence, someone in the future MIGHT add single phase lighting to this panel, he is doing the right thing.
 
Discussion starter · #38 ·
JRaef said:
Trust me, there are a LOT of EEs out there, including those with PE licenses, that know virtually nothing about harmonics, and it scares the bejeebus out of them. So rather than pay attention and learn, they just throw money at things, usually OTHER people's money, to over build equipment. I just did a seminar on harmonic mitigation for VFDs last week, several of the attendees were PEs, who I would have though didn't need to attend. One of them had a difficult time with me telling him that triplen harmonics are not a thing with VFDs (unless fed with a single phase source). I had to go over that several times. He was probably a guy that has been specifying 200% neutrals on 3 phase panels and MCCs that are feeding VFDs.

Now, that said, the 200% neutral IS a good idea on a 480/277V panel that is feeding 277V LIGHTING ballasts, because now they are ALL non-linear loads and create triplen harmonics. So to the earlier points, if he is thinking that by it's mere existence, someone in the future MIGHT add single phase lighting to this panel, he is doing the right thing.
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Great info as per the usual, thank you. I would love to sit in on one of your seminars or classes. Any chance you have one in the greater Pac NW?
 
#39 ·
JRaef said:
.

Now, that said, the 200% neutral IS a good idea on a 480/277V panel that is feeding 277V LIGHTING ballasts, because now they are ALL non-linear loads and create triplen harmonics. So to the earlier points, if he is thinking that by it's mere existence, someone in the future MIGHT add single phase lighting to this panel, he is doing the right thing.
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That is pretty common over here to do that with our Wye system we genrally upsize the netural some. only on lighting loads ., ( 415Y240 volts in our system )

Non lighting loads we just ingore it. run it as conventail arrangement.
 
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cdslotz
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