Brain Tease Photovoltaic System Conductor Residential or Commercial

[jar546]

There are 3 conductors in a conduit within a boiler room where the temperature is approximately 40 deg C, (about 104 F). The continuous current on all 3 conductors is 50A and a 90deg C copper conductor is specified. The terminals to the components are 75deg C.

What size copper conductors are needed?

 

[jar546]

No takers?

No one inspects PV systems?

 

[jar546]

OK, how about at least a heavy hitter helping out on this one. A little participation please so it can be a learning experience. I don't want to ask and answer the question!

 

[north star]

* * * *

Alrighty then!....I'll step out on to this slippery slope.

In referring to Article 690 in the `08 NEC, ...looking at Table 690.31©,

in the Ambient Temp. Column, "36-40" degrees - F, would require a 0.91

correction factor.....Section 690.8 refers to Table 310.16 or 310.17.

Table 310.16 is for "not more than 3 current carrying conductors."

On the copper conductor side of the table, ...on the 55 ampacity line,

the size of the conductor would be a # 8.

No, I don't inspect PV systems either!

Let the stoning begin...



* * * *

 

[jar546]

* * * * Alrighty then!....I'll step out on to this slippery slope.

In referring to Article 690 in the `08 NEC, ...looking at Table 690.31©,

in the Ambient Temp. Column, "36-40" degrees - F, would require a 0.91

correction factor.....Section 690.8 refers to Table 310.16 or 310.17.

Table 310.16 is for "not more than 3 current carrying conductors."

On the copper conductor side of the table, ...on the 55 ampacity line,

the size of the conductor would be a # 8.

No, I don't inspect PV systems either!

Let the stoning begin...



* * * *

Very commendable but you forgot one thing......

Did you apply 215.2(A)(1)?

 

[north star]

* * * *

Well obviously not!

Please clarify the connection research trail for us lurners.....How would someone

know to look at Article 215.2(A)(1) if they are rooting around in Article 690?

Also, what is the correct conductor size?...Other lurking students of the

ee-lek-tri-kull trade might want to know as well.



* * * *

 

[jar546]

The connection is that 215 applies for feeders across the board as a general code requirement and 690 is specific to PV systems. Just like 250 applies to all installations.

 

[north star]

* * * *

That's something that I did not know!...I am learning something new

every day.

* * * *

 

[TimNY]

No takers?No one inspects PV systems?

I do.. I mean.. not my job.. but somebody has to..