Installing A New Generator

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north star

Senior Member
Location
inside Area 51
~ + ~ + ~


I am seeking input from you all........I need some guidance on
a proposed installation of a 300kw generator.

THE EXISTING CONDITIONS:
We currently have a building with an 800 amp service in it.
The MDP does not have a main disconnect in it.


THE PROPOSAL:
We have received a quote from an EC to:
 (1) Provide & install 1 - 800 amp rated fused service rated
disconnect,
(2) Re-work the existing secondary service entrance conductors
& terminate to the line side of new main disconnect,
(3) Provide & install 3 - 3" emt raceways & 800 amp rated wire
from the load side of new main disconnect to a new Manual
Transfer Switch, located near the Generator..............We
specified the MTS vs. an ATS for our needs.
(4) Provide & install 1 - 800 amp rated Manual Transfer
Switch,
 (5) Provide & install 3 - 3" emt raceways and 800 amp wire
from load side of new MTS to the existing MDP and connect,
 (6) Provide & install 3 - 3" pvc raceways and 800 amp wire
underground from the Generator to the MTS. ( NOTE: All
raceways exposed to physical damage shall be RMC ),
 (7) Provide & install required controls from the MTS to the
Generator,
 (8) Provide & install required battery and block heater
circuit from existing electrical panel to Generator,
(9) Grounding & bonding as required,
(10) Testing

In the Quote, the EC states that all work shall be in
compliance with the NEC, but did not reference which
edition.

No information on the length of the raceways, ...type
of conductors, ...exactly how the Grounding & Bonding
would be accomplished, etc.

I do not know for sure, but the length of the raceways
from the Generator to the MDP could be approx. 200 ft.

This is all of the information that I currently have
available, but I will try to answer any questions that
you have.

If possible, ...please cite any discrepancies \ suggestions
\ other from the `05 NEC, as that will be the code of
reference for this project, although it has not been
[ officially ] stated by the EC.

Any input is welcomed, ...and "Much Thanks ! " :thumbsup:


FWIW, ...price is not necessarily the issue, however,
we DO want to ensure that we are getting a code compliant
install [ i.e. - use of Al conductors vs. Cu conductors ].



~ + ~ + ~
 
Wouldn't one assume that the code cycle that is accepted in the area would be the one the ec would comply with. Around here if we use a later or newer code cycle than what has been accepted by the state then you are subject to failure. Just ask the ec what cycle they plan on following.

Why do you need to know the length of the run or the wire size, etc. I have never seen a plan that measures the length of conduit run for you and I don't believe that is a necessary element in a bid.

If you are comparing bids than I would make sure they are both using copper or aluminum conductors but other than that I believe it is a contractors decision. If there is a certain install that you all want then it should be specified on the plans or spec sheet for the bidders to see.
 
I agree with Dennis. The contractor gave you a quote with all the relevant information you need to know, if you wanted something specific it should of been mentioned PRE-bid.

.
 
I agree with Dennis and Cow.


I am baffled why you would expect raceway lengths to be provided in the quote.:huh: I assume the EC is placing the genset in a spot you want.
 
I intentionally leave some detail out of my quotes so the customer cannot give my proposal to another contractor to bid shop after I already did all the research and engineering.

after I receive a contract or PO, I will give the customer more detail.
 
Sounds to me like the EC covered all of the bases. He said he would install everything needed. If this manual transfer switch does not switch the neutral there is no real additional grounding/bonding required for the 800 amp service disconnect, just move the existing GEC(s) there.
 
If the contractor does not install a code compliant project then it will not pass inspection and will not get hookup to the utility grid.
 
~ + ~ + ~


Thanks everyone for your replies !

I do not have direct access to the EC to specify anything
[ at this point ].

My question of the length of the raceways from the
Generator to the MDP has to do with any applicable (1)
derating factors, and (2) the use of Al vs. Cu conductors.

Regarding the inspection of the work, we do not have a
qualified individual to perform this activity, rather, ...we
have [ in the past ] just taken the word of the Contractors
performing the work [ in all trade disciplines, not just
electrical ], and sometimes we have not received what
we expected regarding compliance.

Regarding the NEC edition, I cannot say for sure that
the NEC edition was mentioned or specified when the
Quote was requested.........We have a lot of missing
managerial components in our process.

I am not comparing Quotes with any contractors,
because this is the only Quote we have received so
far.


Continuing with the discussion...

Can we use Al conductors for this application ?
Is there a derating factor to apply because of the
approx. length of the raceways ?

Again, ..."Much Thanks" for your input


~ + ~ + ~
 
north star said:
Regarding the NEC edition, I cannot say for sure that
the NEC edition was mentioned or specified when the
Quote was requested.........
Click to expand...

It seems obvious to me that the EC would be talking about compliance with the current code for that area. Heck if I could choose which code cycle to use life would be easier. :D



Can we use Al conductors for this application ?
Click to expand...

Why not?


Is there a derating factor to apply because of the
approx. length of the raceways ?
Click to expand...

No 'derating'.

If the length is long enough wire size might be increased to overcome voltage drop but the NEC does not require that. It would be a design decision. If the request for a quote did not include specifications for voltage drop I doubt the EC addressed it.
 
I agree with every one else. It looks as if the proposal is straight forward and to the point of what is needed. As far as type conductor, allowing for voltage drop, etc... that is your responsibility to have the specks of what you want. In the contractors defense, as some one else mentioned, its not in his best interest to give every piece of information and /or design the job for some one else.

Regarding the inspection of the work, we do not have a
qualified individual to perform this activity, rather, ...we
have [ in the past ] just taken the word of the Contractors
performing the work [ in all trade disciplines, not just
electrical ], and sometimes we have not received what
we expected regarding compliance
Click to expand...
.

If there are no local inspectors to do inspections then, again, it is your responsibly to bring in some one like a third party agency or engineer to inspect the job. No matter how good or honest the contractor may be, mistakes can be made or something gets overlooked. That is what the other set of eyes are for. On a job of this size it is worth the money to have it inspected by someone else.
 
north star said:
~ + ~ + ~


THE EXISTING CONDITIONS:
We currently have a building with an 800 amp service in it.
The MDP does not have a main disconnect in it.


THE PROPOSAL:
We have received a quote from an EC to:
(1) Provide & install 1 - 800 amp rated fused service rated
disconnect,
(2) Re-work the existing secondary service entrance conductors
& terminate to the line side of new main disconnect,
(3) Provide & install 3 - 3" emt raceways & 800 amp rated wire
from the load side of new main disconnect to a new Manual
Transfer Switch, located near the Generator..............We
specified the MTS vs. an ATS for our needs.
(4) Provide & install 1 - 800 amp rated Manual Transfer
Switch,
(5) Provide & install 3 - 3" emt raceways and 800 amp wire
from load side of new MTS to the existing MDP and connect,
(6) Provide & install 3 - 3" pvc raceways and 800 amp wire
underground from the Generator to the MTS. ( NOTE: All
raceways exposed to physical damage shall be RMC ),
(7) Provide & install required controls from the MTS to the
Generator,
(8) Provide & install required battery and block heater
circuit from existing electrical panel to Generator,
(9) Grounding & bonding as required,
(10) Testing

In the Quote, the EC states that all work shall be in
compliance with the NEC, but did not reference which
edition.

No information on the length of the raceways, ...type
of conductors, ...exactly how the Grounding & Bonding
would be accomplished, etc.

I do not know for sure, but the length of the raceways
from the Generator to the MDP could be approx. 200 ft.

This is all of the information that I currently have
available, but I will try to answer any questions that
you have.

If possible, ...please cite any discrepancies \ suggestions
\ other from the `05 NEC, as that will be the code of
reference for this project, although it has not been
[ officially ] stated by the EC.

Any input is welcomed, ...and "Much Thanks ! " :thumbsup:


FWIW, ...price is not necessarily the issue, however,
we DO want to ensure that we are getting a code compliant
install [ i.e. - use of Al conductors vs. Cu conductors ].
Click to expand...

I'm guessing:
  • You are inside a government facility and You (plural - as in the owner's agents) are the AJH.
  • You don't have an engineer of record.
  • You don't have any prints of the proposed installation - other than what the contractor gave you.
  • You requested a design/build estimate from the contractor.
  • The specs given the the contractor were something like a one paragraph:
"Install a 300KW generator and manual transfer switch to fit existing service."

From this point of view (provided any of this is true) - you have a tough road.

You didn't pay for the engineering, and as said by others, no one is interested in giving their work away. You have only one contractor that bid. You can't afford to piss them off. Telling the contractor to resubmit with prints is likely not a good idea.

So given this, just ask:
We have specific concerns -
What are you using for full load voltage drop on the new conductors?
Are you planning on a 3W or 4W transfer switch?
What code year are you using? Although, since you are the AHJ - better yet, you tell them. Maybe too late for that.
If I were the EC, I'd tell you. If you wanted much more, I'd tell you to pay for the engineering. But they may not even be able to charge you for the engineering. If they don't have a PE they likely can't do engineering for hire.

As for Al conductors, as other have said, it is not a code issue, it is a design spec, generally based on owner's preference. Since you didn't specify - ask: Are you using Cu or Al conductors?

Regarding the inspection of the work, we do not have a
qualified individual to perform this activity, rather, ...we
have [ in the past ] just taken the word of the Contractors
performing the work [ in all trade disciplines, not just
electrical ], and sometimes we have not received what
we expected regarding compliance. ...
Click to expand...

Only two ways I know of:
Hire the engineering/inspection services expertise, or keep doing what you have been doing.

ice
 
+ ~ + ~ +


Again, ..."Much Thanks" to you all for your invaluable replies.
You have given me some great direction in which to proceed.



iceworm,

Yes, ...you have astutely determined my situation down to a
tee..........I am performing some "due diligence" after-the-fact,
so we can try to make a "silk purse out of this sow's ear". :slaphead:



FWIW, ...by the dollar amount on the Quote we recv'd, ...I'm
guessing that the EC planned to use Cu instead of Al
conductors.



~ + ~ + ~
 
I would just add as part of your due diligence:

I would look into providing/allocating some budget to have an arc flash calculation and signage installed.

I would be concerned about switching a 800 amp manual transfer switch, especially when the existing loads would likely not be shed.

I realize that (depending on the switch) the switching is done electronically through a user interface. You might want to look into a remote user interface (depending on the switch) to keep personnel out of harms way when using the equipment.

Have you looked into going with an ATS and keeping it manual? That way you could always go back to the Automatic mode if things change?

As far as the estimate goes it appears fine to me. The only thing I would specify is that "all new equipment to match existing equipment AIC"

Joe Villani
 
iwire said:
If the switch is rated for the load it should be safe correct?
Click to expand...

I agree with Bob on that one.


Have you looked into going with an ATS and keeping it manual?
Click to expand...

IMO that would be more dangerous that a manual switch. To manually operate a ATS you have to have the cabinet door open which would leave someone more exposed than operating a manual transfer switch.
 
= & = & =


"Much Thanks" again to all for the replies !

As I understand the intended use of the Manual
Transfer Switch ( MTS ), ...we would only transfer
to the Generator when all power is lost to the
facility from the POCO......We had to do this
very same thing last summer, at one of our
other facilities.

Sometime back, I asked our leadership if we
were planning to install an ATS vs. an MTS,
and they said No, because of the infrequency
of the use & cost of an ATS.


= & = & =
 
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