Minimum AWG wire that can feed a sub panel

[infinity]

Thats not a continuous rating.

Plastic Pipes - Maximum Operating Temperatures

Piping materials like ABS, PE, PVC, CPVC, PB, PP and SR and pressure and operating temperature limits.

www.engineeringtoolbox.com

But perhaps ok for residential feeders not considered continuous loads.

Continuous rating, what does that even mean? PVC with THWN, 75° C terminals on each end, 75° C ampacity. What am I missing?

 

[ramsy]

Continuous rating, what does that even mean? PVC with THWN, 75° C terminals on each end, 75° C ampacity. What am I missing?

UL standards testing with "Current Cycling" for 1hr on 1hr off x 500 cycles takes several months, and may be rigorous, but its not a continuous-load test > 3 hrs.

 

[retirede]

UL standards testing with "Current Cycling" for 1hr on 1hr off x 500 cycles takes several months, and may be rigorous, but its not a continuous-load test > 3 hrs.

EVSE branch circuits (continuous load) are routinely installed in PVC conduit using 75C conductor ampacity. I’ve not heard of any failing inspections nor any issues.

 

[don_resqcapt19]

UL standards testing with "Current Cycling" for 1hr on 1hr off x 500 cycles takes several months, and may be rigorous, but its not a continuous-load test > 3 hrs.

That is not what UL 651, Schedule 40, 80, Type EB and A Rigid PVC Conduit and Fittings says. It says continuous operation until the PCV reaches the maximum stable temperature and at that temperature there cannot be any material changes in the critical properties of the conduit. It goes on to specify a number of impact and bending tests at the maximum stable temperature.

​

 

[ramsy]

EVSE branch circuits (continuous load) are routinely installed in PVC conduit using 75C conductor ampacity. I’ve not heard of any failing inspections nor any issues.

Another advantage of inspections, which can overrule engineers that may not specify PVC on plans.

 

[augie47]

Another advantage of inspections, which can overrule engineers that may not specify PVC on plans.

From Carlon's website:
Our conduit and duct is rated for 90 deg C conductors. The DB duct is not
UL listed, however. The Plus 40 and Plus 80 is actually UL listed for 90 C
conductors. E35297 is our UL file number. C

 

[ramsy]

That is not what UL 651, Schedule 40, 80, Type EB and A Rigid PVC Conduit and Fittings says. It says continuous operation until the PCV reaches the maximum stable temperature and at that temperature there cannot be any material changes in the critical properties of the conduit. It goes on to specify a number of impact and bending tests at the maximum stable temperature.

You were not supposed to actually look that up.

Now I must accept that "current cycling" from UL 486C §7.2 is not a universal testing standard, or that industry jargon for PVC conduit may actually be Chlorinated Polyvinyl Chloride (CPVC), with an extra chlorine atom in its structure that extends the service temperature to about 180 - 200°F (82 - 93°C).

Regardless, I stand by my original statement in post #8 that Owner-builder permits are the OP's best advice, since inspectors will overrule speculation from people like me, acting like arm-chair generals on the internet.

 

[retirede]

You were not supposed to actually look that up.

Now I must accept that "current cycling" from UL 486C §7.2 is not a universal testing standard, or that industry jargon for PVC conduit may actually be Chlorinated Polyvinyl Chloride (CPVC), with an extra chlorine atom in its structure that extends the service temperature to about 180 - 200°F (82 - 93°C).

Regardless, I stand by my original statement in post #8 that Owner-builder permits are the OP's best advice, since inspectors will overrule speculation from people like me, acting like arm-chair generals on the internet.

You are our best goal post mover!

 

[don_resqcapt19]

You were not supposed to actually look that up.

Now I must accept that "current cycling" from UL 486C §7.2 is not a universal testing standard, or that industry jargon for PVC conduit may actually be Chlorinated Polyvinyl Chloride (CPVC), with an extra chlorine atom in its structure that extends the service temperature to about 180 - 200°F (82 - 93°C).

Regardless, I stand by my original statement in post #8 that Owner-builder permits are the OP's best advice, since inspectors will overrule speculation from people like me, acting like arm-chair generals on the internet.

486C is a wire splicing standard, and the expansion and contraction from cycling the current would be an important part of a test for a splicing connector, but as I recall, that standard also has a continuous test.

UL 651 permits the PVC conduit to be construction of PVC, mixed PVC and CPVC, or CPVC that comply with ASTM D 1784.

 

[Speedskater]

I'm late. (I was at my grandson's soccer game, 91°F)
Why a sub-panel?
Why not a 6 breaker box?

 

[infinity]

Why a sub-panel?
Why not a 6 breaker box?

Isn't that the same thing?

 

[Eddie702]

@ramsy I don"t think your "plastic pipe operating temp " applies to conduit. Looks like plumbing to me

 

[david]

230.79(C) only applies if meter is installed.

225.39(C) only applies with occupancy.

Is this a local ammendment the text in 225.39 uses the term installations.

The Feederor branch circuit disconnecting means shall have a rating not less than the calculated load to be supplied
And goes onto to say

in no case shall the rating be lower than specified

 

[ramsy]

Is this a local ammendment the text in 225.39 uses the term installations.

If AHJ in 90.4 says it meets the definition of "Garage" in Art.100, then 210.11(C)(4) applies.

 

[ramsy]

don"t think your "plastic pipe operating temp " applies to conduit. Looks like plumbing to me

Did not find the ASTM standard explaining this, but I believe you are correct, as Don noted in post #29, "White" plumbers PVC pipe may be modified for higher pressures, and "Grey" electricians PVC conduit may be CPVC modified for higher temperature wires.

 

[Speedskater]

Isn't that the same thing?

Doesn't a sub-panel have (or have space) for a main breaker?

 

[LarryFine]

Doesn't a sub-panel have (or have space) for a main breaker?

Not necessarily. An MB or an ML panel may be used as a sub-panel, as long as the neutral can be unonded.

 

[ramsy]

Is this a local ammendment the text in 225.39 uses the term installations.

Dwelling garages should be considered for 90.1(B) future expansion, as described in the last 2 sentences of post #9.

Garages wired with a single branch per 210.11(C)(4), become uninsurable with the "increased hazard" of occupancy, not insured against when policies are signed.

"Increased Hazard" is the cause most State's insurance codes use for non-renewal and cancellation, if not complete loss after casualty.

 

[david]

225.1 scope (paraphrased)
The wiring between buildings on the premise

And electrical equipment and wiring for the supply

On or attached to the outside of buildings
structures or poles
225.39 the rating of the disconnects and calculating the load are to size and ptotect the supply conductors between the buildings

Looking at225.39 (C)
When it says 3-wire it telling you it's not just about the disconnect rating, it is also about the supply conductors

By telling uou in (C) it has to be a three wire supply as a min. It is also telling you that (A,B & D) can be a 2-wire supply as a min.
225.39 establishes min requirements for the supply conductors and the rating of the disconnects to protect the supply .

As soon as you install these disconnects inside they have nothing to do with article 225 except how they effect what is covered under the scope of article 225 and that would be the supply conductors between the buildings

 

[ramsy]

225.1 scope (paraphrased)

Are you saying 210.11(C)(4) wont apply to the OP?