Allowable Voltage Drop

[KWH]

The power company changed the location where my secondary's will terminate on a new job still in the planning stages. I was wanting to make sure I did not need to make adjustments for voltage drop since the new location almost doubled the distance, concerning the whole service would you base this on 3% or 5%.

Thanks

 

[xformer]

I would use 2% just to be on the safe side...
See 210.19 A1 FPN #4

The note says that the 3% is just for a branch circuit. For the Feeder and the Branch circuit its a total of 5%.

 

[Hameedulla-Ekhlas]

I would use 2% just to be on the safe side...
See 210.19 A1 FPN #4

The note says that the 3% is just for a branch circuit. For the Feeder and the Branch circuit its a total of 5%.

But it has also not mentioned clearly that for feeder should be 2%.
I can gues it like this

It is assential, not to increase than 3% for branch and the total branch plus feeder drop should be less than 5%.

Suppose,
I calculate voltage drop for branch it comes 2% and I calculate for feeder it comes 2.7%
The total becomes 4.7%
Am I wrong?

 

[chris kennedy]

If you based your load calcs on the NEC your over-engineered to begin. Can you give us the details such as load, system, length, conductor size, type, ect?

 

[xformer]

But it has also not mentioned clearly that for feeder should be 2%.
I can gues it like this

It is assential, not to increase than 3% for branch and the total branch plus feeder drop should be less than 5%.

Suppose,
I calculate voltage drop for branch it comes 2% and I calculate for feeder it comes 2.7%
The total becomes 4.7%
Am I wrong?

I am in agreement with you that 2% and 2.7% = 4.7% Which would be less than the 5% which will provide for reasonable efficiency...

 

[xformer]

If you based your load calcs on the NEC your over-engineered to begin. Can you give us the details such as load, system, length, conductor size, type, ect?

Are you saying that by calculating each to 3% is safe due to over-engineering??

 

[chris kennedy]

Are you saying that by calculating each to 3% is safe due to over-engineering??

Just voicing experience, 220 is very conservative to what you will see in the field for a service at full load. And as stated in a previous post, VD is a FPN, not enforceable for this application.

 

[weressl]

But it has also not mentioned clearly that for feeder should be 2%.
I can gues it like this

It is assential, not to increase than 3% for branch and the total branch plus feeder drop should be less than 5%.

Suppose,
I calculate voltage drop for branch it comes 2% and I calculate for feeder it comes 2.7%
The total becomes 4.7%
Am I wrong?

% of what? The delivered voltage at each point, the delivered voltage at the service point, at the use point, of the nominal value?

Again these values are not regulated and defined by the NEC.

 

[Jim W in Tampa]

Unless they changed it this is still a foot note and not code.
With out real numbers it is hard to say if you have a problem. Double what ? If original was 50 feet and your now 100 might not be problem but if 100 just went to 200 then yes worry.

 

[Smart $]

The power company changed the location where my secondary's will terminate on a new job still in the planning stages. I was wanting to make sure I did not need to make adjustments for voltage drop since the new location almost doubled the distance, concerning the whole service would you base this on 3% or 5%.

Thanks

The only one that can truly provide enough info to make that determination is the POCO... because it all depends on what voltage they will be supplying you with, actual based on your calculated load... not the nominal... you already know that.

In summary, if you don't know what you are starting with, how can you plan for voltage drop % and stay above nominal tolerance.

 

[Hameedulla-Ekhlas]

% of what? The delivered voltage at each point, the delivered voltage at the service point, at the use point, of the nominal value?

Again these values are not regulated and defined by the NEC.

Suppose I have
Generator
1- Main Distribution Panel (MDP)
2-Panel Board
3-Equipment

From Generator to Main Distribution panel for feeder voltage drop is 0.5%
From Main Distribution panel to panel board ( which is located in building) for feeder is 2.2% drop
From panel Board to equipment ( which is branch ) is 2%

Now,
The total voltage drop for feeder becomes 2.7%
The total voltage drop for branch becomes 2%

The total voltage drop for branch + feeder becomes 4.7%

Now any comment?

 

[KWH]

More Info on the Service

More Info on the Service

The service is 400amp 120/240 single phase underground

The distance is 250ft

I have #250al paralled in 2 1/2" pvc ( 3 per conduit )

The connected load for the service is 60kw

The service consists of (2 ) 200amp main breaker panels

The POCCO change added about 120ft to my secondary length.

Thanks

 

[KWH]

The distance I listed is incorrect

The distance I listed is incorrect

The correct length is 190ft not 250ft


Thanks

 

[jumper]

The service is 400amp 120/240 single phase underground

The distance is 250ft

I have #250al paralled in 2 1/2" pvc ( 3 per conduit )

The connected load for the service is 60kw

The service consists of (2 ) 200amp main breaker panels

The POCCO change added about 120ft to my secondary length.

Thanks

A quick calc shows that you may only be off by .54v for 5%. If correct I would not worry about it.

 

[jumper]

the correct length is 190ft not 250ft


thanks

190 + 120?

 

[Jim W in Tampa]

Is this residential single family or commercial ? If residential chances are you will be ok.

 

[KWH]

The total length is 190ft

The total length is 190ft

The total secondary length is 190ft.


Thanks

 

[jumper]

The total secondary length is 190ft.


Thanks

I am pretty sure you are okay, here is a link for a cheater calculator. It is at the bottom.

http://www.mikeholt.com/freestuff.php?id=freegeneral

 

[KWH]

This is a commercial project

This is a commercial project

This is a funeral home , the only real load is the A/C's it has gas heat, mainly just general lighting and receptacle loads

 

[jumper]

It may be wrong, but I was taught that as a general rule that you need only worry about VD for 120v at 150 ft and 240v at 300 ft. Single phase only.