Follow manufacture instructions or code

Status
Not open for further replies.
D

Dmc16

Member
Location
Sparta,nj,United states
Started a 20 kw generator. It is ge, which has 100 amp breaker in it. Install manual gives a chart, for this model #4 cu or #2 al, 300 v, 75 c. Also defers to 310.15 b 16 per 2011 for correction factors and calcs.
Was not paying attention for wire rating, but 4 is 85, 2 90. So if I had to I could downsize breaker according to 240.6, no 85 breaker.
Inspector had started to challenge on trench inspect. Wire pulled already, #4 cu in pipe to generator, 100 a ser to box in basement to meet up with pipe.
my argument is the book specs it, although it may be wrong, follow manufactures instructions. Or is ge covered since they defer to code?
 
Manufacturer's instructions for anything field installed cannot not be less than the minimum requirements of the code.
 
Dmc16 said:
Started a 20 kw generator. It is ge, which has 100 amp breaker in it. Install manual gives a chart, for this model #4 cu or #2 al, 300 v, 75 c. Also defers to 310.15 b 16 per 2011 for correction factors and calcs.
Was not paying attention for wire rating, but 4 is 85, 2 90. So if I had to I could downsize breaker according to 240.6, no 85 breaker.
Inspector had started to challenge on trench inspect. Wire pulled already, #4 cu in pipe to generator, 100 a ser to box in basement to meet up with pipe.
my argument is the book specs it, although it may be wrong, follow manufactures instructions. Or is ge covered since they defer to code?
Click to expand...

Sorry I fail to see the problem
Is this a residential generator?
If so why would you not be able to use the wire size allowed for service entrance?
 
Yes it is only a residential generator. I've been reading the generacs come with a 90 factory installed. Which matches the wire. Online manual even shows it. Interesting comparison.
I am going to give manufacturer a call see if they will provide new breaker if needed since they spec the wire. Also going to question the reasoning on the wire they have suggested, and see if I can argue the point with inspector.
Ugh :rant:
 
Sierrasparky said:
Sorry I fail to see the problem
Is this a residential generator?
If so why would you not be able to use the wire size allowed for service entrance?
Click to expand...

iwire said:
Because it is not a service or feeder carrying the entire load of the house.
Click to expand...

Really,

So when the geny is running and the transfer switch is thrown the entire load of the house is not on the Genny?

Seems to me that even if the house main is a 400 it is now a 100 when the genny is running.

IMHO
 
Sierrasparky said:
Really,

So when the geny is running and the transfer switch is thrown the entire load of the house is not on the Genny?

Seems to me that even if the house main is a 400 it is now a 100 when the genny is running.

IMHO
Click to expand...

Nope, it is not carrying the entire load of the dwelling.
 
iwire said:
Nope, it is not carrying the entire load of the dwelling.
Click to expand...
If the load calculation of the feeder is 100 amps or less and includes all the loads in the house then I don't see the conductor size as an issue, it is a feeder supplying all the dwelling unit load and qualifies for the provisions of 310.15(B)(7)

If there is load shedding methods utilized to reduce the connected load, then it may not meet those provisions.
 
I was under impression 310.15 b7 was for service feeders only. Really annoyed that I followed book, which refers you to 310.16 to cover their rear. How did it get past ul approval process etc etc.
310.15 had caused me confusion in the past because according to that chart yes 4,2 good for 100 amp service.
 
iwire said:
But it doesn't so you post was pointless
Click to expand...
Where were we told what the connected load is?

All I get from OP is it runs to "100 a ser to box in basement to meet up with pipe" whatever that is supposed to mean.

If this isn't a dwelling then all of the discussion of possible reduced conductor is pointless.
 
kwired said:
Where were we told what the connected load is?

All I get from OP is it runs to "100 a ser to box in basement to meet up with pipe" whatever that is supposed to mean.

If this isn't a dwelling then all of the discussion of possible reduced conductor is pointless.
Click to expand...

You think 20KW is a whole home generator?

You think the inspector is unaware of the reduced feeder sizes in dwelling units?

How about we wait for the OP to respond before going out in the weeds.
 
Do not think it matters what connected load is. The generator is for a dwelling unit. "Box in basement" is to transition from ser to pvc run out to generator 10' or so off house. My whole concern, point, question, is how does manufacture spec #4 cu or #2 al in their install instructions when it seems like it does not meet code for wire ampacity. For example #2 al xxhw (found in 100 a ser) is good for 90, not 100, which is the breaker in the ge 20 kw generator. ??????
 
Status
Not open for further replies.
Top