Disconnect

[Bryan-79]

2023 NEC
The 80 % can't be found for the disconnect.

It's the reciprocal of 125% which is what the NEC uses for continuous duty.

Example: 1 / 1.25 = 0.8 or 80 %
Example : 1/ .80 = 1.25 %

Panelboard's and disconnects have that 80 % rating.

When we size our continuous loads the NEC requires 125% of the load, so that satisfies the '80 %' rule.

Make sense? Sure does, 'cause NEC says so.

Oh, I can't forget to say.......
Thanks for reading.
Comments accepted.
TX+MASTER #4544

Where in the nec can I find the 125%

 

[Bryan-79]

Where in the nec can I find the 125%

1.25%

 

[Dennis Alwon]

1.25%

It is 1.25 which is the same as 125%

430.22 Single Motor.

Conductors that supply a single motor used in a continuous duty application shall have an ampacity of not less than 125 percent of the motor full-load current rating, as determined by 430.6(A)(1), or not less than specified in 430.22(A) through (G).

 

[Jraef]

It is 1.25 which is the same as 125%

But to be clear though, this applies to the CONDUCTORS, not the disconnect switch.

An UNFUSED disconnect switch, for MOTORS, is required to have a HP rating equal to or greater than the motor HP. If you don't KNOW the HP rating, or the switch is fused, then 115% of the motor FLA rating.

But in this case, the disconnect switch has a rating plate specifically stating that it's good for 50HP, so that satisfied the NEC. You don't need to know how they got there.

430.110 Ampere Rating and Interrupting Capacity.
(A) General. The disconnecting means for motor circuits
rated 1000 volts, nominal, or less shall have an ampere rating
not less than 115 percent of the full-load current rating of the
motor.
Exception: A listed unfused motor-circuit switch having a horsepower
rating not less than the motor horsepower shall be permitted to have an
ampere rating less than 115 percent of the full-load current rating of
the motor.

 

[Dennis Alwon]

But to be clear though, this applies to the CONDUCTORS, not the disconnect switch.

An UNFUSED disconnect switch, for MOTORS, is required to have a HP rating equal to or greater than the motor HP. If you don't KNOW the HP rating, or the switch is fused, then 115% of the motor FLA rating.

But in this case, the disconnect switch has a rating plate specifically stating that it's good for 50HP, so that satisfied the NEC. You don't need to know how they got there.

The poster asked about 125% so I posted what I knew about 125%. Yes it is for the conductors and not to disconnect

 

[TX+ MASTER#4544]

Where in the nec can I find the 125%

2023 NEC

This is what I call making the 'loop' branch circuits, feeders, and services. There are several other continuous loads found in your Code book.

For Branch Circuits 210.19 Conductors -Minimum Ampacity and Size (A) (1) General ......125%
For Branch circuits 210.20 (A) Overcurrent Protection.... Branch Circuits Continuous and Noncontinuous Loads

For Feeder Conductors Sizing Minimum Rating and Size 215.2(A)(1)
For Feeder Overcurrent Protection 215.3..... 125 %

For Service Conductors Minimum Size and Ampacity 230.42 (A) (1)
For service Overcurrent Protection Where Required 230.90 (A) and Exception No.2

However, you will find the 125% factor for several other various types of other continuous loads, so you must refer to them when it's necessary and not just in the references that I have listed above.
Hope this is helpful.

Thanks for reading.
Comments accepted.
TX+MASTER#4544

 

[don_resqcapt19]

2023 NEC

This is what I call making the 'loop' branch circuits, feeders, and services. There are several other continuous loads found in your Code book.

For Branch Circuits 210.19 Conductors -Minimum Ampacity and Size (A) (1) General ......125%
For Branch circuits 210.20 (A) Overcurrent Protection.... Branch Circuits Continuous and Noncontinuous Loads

For Feeder Conductors Sizing Minimum Rating and Size 215.2(A)(1)
For Feeder Overcurrent Protection 215.3..... 125 %

For Service Conductors Minimum Size and Ampacity 230.42 (A) (1)
For service Overcurrent Protection Where Required 230.90 (A) and Exception No.2

However, you will find the 125% factor for several other various types of other continuous loads, so you must refer to them when it's necessary and not just in the references that I have listed above.
Hope this is helpful.

Thanks for reading.
Comments accepted.
TX+MASTER#4544

What are these long posts all about???...they are very difficult to read and appear to be written my AI and not a real person. They add no value to the threads they are posted in.

 

[TX+ MASTER#4544]

What are these long posts all about???...they are very difficult to read and appear to be written my AI and not a real person. They add no value to the threads they are posted in.

2023 NEC
I suppose I could have just told him to look in the Index or look in the particular Code chapter and navigate around until you find what your looking for.

The poster ask a simple question, although I think it is a little more than that, so with respect to his question I gave what I thought to be the answer he is looking for. And this was it because "the loop" covers a lot of branch cirs. feeders and services. I assure you an "AI" cannot do this. I did it.

 

[don_resqcapt19]

2023 NEC
I suppose I could have just told him to look in the Index or look in the particular Code chapter and navigate around until you find what your looking for.

The poster ask a simple question, although I think it is a little more than that, so with respect to his question I gave what I thought to be the answer he is looking for. And this was it because "the loop" covers a lot of branch cirs. feeders and services. I assure you an "AI" cannot do this. I did it.

I just see no value in your long winded posts