480/277 feeder

[Piramyd]

Hey there!

I would need your help to size a feeder for 277/480 v 3 ph 4 w.
I know all the derate factor and correction from the NEC.
I understand that the neutral from the switchboard should be considered as current carrying conductor.
Is that correct?
And my other question is regarding how rough anticipate about which percentage
of continuous load and no continuous load, it will be necessary.
It's about a warehouse where it'll be 3- 180 feet feeders from the main Switchboard
to three 277/480 V tenant panels. Space so far is empty and it should be ready for eventual tenant improvement.

Thank you for some help.

 

[infinity]

Unless a majority of the load is non-linear the neutral would not need to be counted as a CCC. Unless your feeding a panel in something like a data center your feeder would only have 3 CCC's.

 

[tom baker]

To size a feeder you need the load. We can't help you with the load as that depend on heating, cooling, lights and so on

The load will be calculated in KW or KVA. Then convert to amps, and size the wire. Thats a short distance you are running and VD shouldn't be factor but you can check it.
Take the amps and use table 310.16 to get the wire size at 75 Deg C

 

[kwired]

Amount of load for each tenant space could vary greatly, unless you have a specific target for tenant type then you may be able to get somewhat an idea what to expect. Small retail with mostly dry goods may not need much power. Restaurant with mostly electric cooking appliances and some refrigeration units will be quite a bit more in most cases.

 

[LibertyEngineering]

Agree with kwired, need to know the loads for the feeders or we will be unable to assist you.

 

[petersonra]

Hey there!

I would need your help to size a feeder for 277/480 v 3 ph 4 w.
Feeders are sized based on calculated loads. You need to know what the loads are.

I know all the derate factor and correction from the NEC.
Really? All of them?

I understand that the neutral from the switchboard should be considered as current carrying conductor.
Is that correct?
Most cases it is not considered a CCC.

And my other question is regarding how rough anticipate about which percentage
of continuous load and no continuous load, it will be necessary.
The code tells you what a continuous load is. Look in article 100. Incidentally some loads are to be considered as continuous even if they do not meet the definition in article 100.

It's about a warehouse where it'll be 3- 180 feet feeders from the main Switchboard
to three 277/480 V tenant panels. Space so far is empty and it should be ready for eventual tenant improvement.
If it is empty the existing loads are probably pretty low. Maybe a few electric door openers, some receptacles, and lighting. Heat is likely gas, while there might be a small electric water heater for hot water. Probably no air conditioning.

Thank you for some help.

I don't think there is a lot we can do for you without more information.

 

[infinity]

You need to design the feeders based on the current calculated load for the space. If you end up with one that is too small for the future tenant then someone will need to upgrade it in the future. We usually come up with the minimum required size and then let the guy who paying the bill decide if he want to exceed the minimum size required for future expansion.

 

[Piramyd]

Thank you very much all of you for the comments and answers

I learned a lot.