Wire size for 200 amps service.

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At the company we use 2/0 Aluminum wire for a 150 amps service and 4/0 for 200 amps services.
Does this mean that the terminations at the meter are rated for 90 C degrees?
 

kwired

Electron manager
Location
NE Nebraska
At the company we use 2/0 Aluminum wire for a 150 amps service and 4/0 for 200 amps services.
Does this mean that the terminations at the meter are rated for 90 C degrees?

Not necessarily.

2/0 has a 75C ampacity of 135.

4/0 has a 75C ampacity of 180.

Next higher standard overcurrent protection devices are 150 and 200.

240.4(B) allows you to use next higher standard overcurrent device when conductor ampacity lands between devices - but the load must still be no more than conductor ampacity. So that 4/0 can be loaded to 180 amps and protected by a 200 amp device. with a load of 181 amps you will need to increase conductor size but can still have the 200 amp device.
 

infinity

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At the company we use 2/0 Aluminum wire for a 150 amps service and 4/0 for 200 amps services.
Does this mean that the terminations at the meter are rated for 90 C degrees?

This is one example of when the 83% rule for dwellings wouldn't change the conductor size if you were installing these services in a non-dwelling. Although the end result may be the same the applicable code sections would be different that's why David asked if this were for a residential service. It has nothing to do with 90° C terminals.
 

kwired

Electron manager
Location
NE Nebraska
This is one example of when the 83% rule for dwellings wouldn't change the conductor size if you were installing these services in a non-dwelling. Although the end result may be the same the applicable code sections would be different that's why David asked if this were for a residential service. It has nothing to do with 90° C terminals.

Not every time. When taking advantage of 240.4 (B) and using next size up OCCP - with dwelling and the 83% rule 4/0 aluminum is acceptable if you have 190 amps of calculated load. If you have non dwelling and 190 amps of calculated load you must use at least 250 aluminum.
 

infinity

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New Jersey
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Not every time. When taking advantage of 240.4 (B) and using next size up OCCP - with dwelling and the 83% rule 4/0 aluminum is acceptable if you have 190 amps of calculated load. If you have non dwelling and 190 amps of calculated load you must use at least 250 aluminum.

Yes, my response was based on your first post where you outlined the next size up rule.
 

jxofaltrds

Inspector Mike®
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Mike P. Columbus Ohio
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ESI, PI, RBO
Not necessarily.

2/0 has a 75C ampacity of 135.

4/0 has a 75C ampacity of 180.

Next higher standard overcurrent protection devices are 150 and 200.

240.4(B) allows you to use next higher standard overcurrent device when conductor ampacity lands between devices - but the load must still be no more than conductor ampacity. So that 4/0 can be loaded to 180 amps and protected by a 200 amp device. with a load of 181 amps you will need to increase conductor size but can still have the 200 amp device.
I did a finished basement 13 years ago and had to provide a load calculation. Neither I, as the contractor, nor the inspector caught that my 185 AMP calculation made a conductor size increase required. Easy to get tunnel vision when we assign values and forget what code section permits that installation.

Sent from my SM-T350 using Tapatalk
 

infinity

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New Jersey
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I did a finished basement 13 years ago and had to provide a load calculation. Neither I, as the contractor, nor the inspector caught that my 185 AMP calculation made a conductor size increase required. Easy to get tunnel vision when we assign values and forget what code section permits that installation.

For a dwelling even with a 200 amp calculated load you can still use the 83% rule so #4/0 at 180 amps is code complaint.
 

kwired

Electron manager
Location
NE Nebraska
For a dwelling even with a 200 amp calculated load you can still use the 83% rule so #4/0 at 180 amps is code complaint.
Yes, must be a conductor supplying the entire dwelling to be able to use that rule.

83% of 200 is 166, 4/0 aluminum with ampacity of 180 is still over that. What changed since they ditched the chart for 83% is you now can have an adjusted ampacity that can require increasing conductor size, so if adjustments make the ampacity less than 166 an increase in size is necessary.
 

infinity

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Location
New Jersey
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Yes, must be a conductor supplying the entire dwelling to be able to use that rule.

83% of 200 is 166, 4/0 aluminum with ampacity of 180 is still over that. What changed since they ditched the chart for 83% is you now can have an adjusted ampacity that can require increasing conductor size, so if adjustments make the ampacity less than 166 an increase in size is necessary.

I quoted post #9 because I was commenting directly on the the fact that even though his increased load brought his calculation (185 amps) above the 180 amp ampacity of the conductors a larger conductor still is not required.
 
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