150kw Genny

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dcspector said:
445.13 @ 115% I would say 600 amps.
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Greg, IMO this applies the the Type W cable in the genny to the gennies breaker.

445.13 Ampacity of Conductors.
The ampacity of the conductors from the generator terminals to the first distribution device(s) containing overcurrent protection shall not be less than 115 percent of the nameplate current rating of the generator. It shall be permitted to size the neutral conductors in accordance with 220.61. Conductors that must carry ground-fault currents shall not be smaller than required by 250.30(A). Neutral conductors of dc generators that must carry ground-fault currents shall not be smaller than the minimum required size of the largest conductor.
Exception: Where the design and operation of the generator prevent overloading, the ampacity of the conductors shall not be less than 100 percent of the nameplate current rating of the generator.
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Greg

"...to the first distribution device(s) containing overcurrent protection shall not be lessthan 115 percent"



Would you consider the CBer located in the generator as the first overcurrent protection? Which would preclude the need for sizing the conductors at 115%.
or
Do you believe the 115% sizing factor is still necessary with the generator overcurrent device in place?
 
Second,
This is another contractor's job and we are only installing the ATS and associated wiring.
There are two 1" pvc's and two 4" pvc's.
One 1" for control wiring and the other for 120v circuit.
One of the 4"s is broken underneath parking lot.
I say we need to rerun the conduit and architect says we can use the one 4".
Can I fit 600A conductors in one 4"?
Run is about 200'
 
walkerj said:
Second, Can I fit 600A conductors in one 4"?
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Do you know how to do a fill calc? I'll give you a hint:
Table 310.15(B)(2)a
Table 310.16
Ch. 9 Table 4 & 5

It goes along with that expression: Give a man a fish and feed him for a day......

You need to know how to do these calcs for yourself.
 
I am not the arch/engineer.
I would do two sets of 500kcmil.
I know I can't get by with the one conduit.
He thinks I can.
I just need some backup.:cool:
Thanks.
 
Jason,

Is the genny a 3? wye?

Is the ATS a 3 or 4 pole?

Are the majority of the loads non-linear?

Need to know this to help you size conductors and conduit.
 
Hey Jason,

Sorry I mis read but I do that a lot on the Forum. Looks like you have it under control and that broken 4" is a killer. The back up you need is what you knew already........repairing the other 4'' if possible is an option. let us know my friend.:smile:
 
The problem is it is two conduits.
Repairing would mean repairing the brand new parking lot also.
We can't just rerun one conduit because they would be two different lengths.:mad:

At least we didn't run the conduit so it is change order city :grin:
 
chris kennedy said:
Jason,

Is the genny a 3? wye?

Is the ATS a 3 or 4 pole?

Are the majority of the loads non-linear?

Need to know this to help you size conductors and conduit.
Click to expand...


600A 208y/120
3-pole ATS
A/c's, servers(software makers), and lighting.
It is sized for the entire building load.

I haven't set foot inside this building nor seen any load calcs.

How do you make the phase symbol?
 
If you use 3 sets of 4/0 copper and a #1 EGC you can fit it in the single 4" PVC. The ampacity of 3 sets of 4/0 THWN-2 after derating, assuming the neutral is not a current carrying conductor, is 546 amps. This should be greater than the calculated load as the generator is only rated at 520 amps and the OCPD can be rounded up to the next standard size permitting the use of the 600 amp breaker.
 
Thank you, Don.

I have never ran parrallel sets in one conduit.
I need just the one EGC, correct?
What if the neutral is a CCC?

That sounds like a bear of a pull.
 
You could also use a tool like this with a pipe bursting attachment if the conduit is straight. It would only require excavation at each end. You send it through the existing conduit with a head to burst and expand the conduit enoungh to install new conduit inside the expanded original conduit. Note, if the conduit is concrete encased, I don't think this will work.
 
Pierre C Belarge said:
Don
Would you mind showing your calculation?
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Pierre,
The 4/0 is rated at 260 amps in the 90?C column. If the grounded conductor is not a current carrying conductor we have 9 current carrying conductors and a 70% derating giving you 182 amps per conductor. Three sets would give you 546 amps. I see this as complying with the code rules for this installation.
 
walkerj said:
Thank you, Don.

I have never ran parrallel sets in one conduit.
I need just the one EGC, correct?
What if the neutral is a CCC?

That sounds like a bear of a pull.
Click to expand...
As far as the pull you can do an online pulling calculation here. I don't think it would be too bad assuming there are a not a lot of bends and you have a tugger. A single EGC is permitted by the code for this application.
If the neural is a current carrying conductor you can do it with 4 sets of 4/0 compact strand copper. The derating would be 50% so each conductor would have an ampacity of 130 amps and 4 sets gives you 520 amps. The load cannot be greater than that as 520 is the rated output of the generator. 240.4(B) permits this 520 amp set of conductors to be protected by a 600 amp OCPD.
 
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