Feeder calculation for fork lift charging station

[ArtZat]

I have a dilemma that I'm hoping you can assist with. I've only done residential and light commercial work thus far but I'd like to grow my business and I have the opportunity to bid on a sizable industrial project. The client has an existing charging station with 20 chargers fed from two load panels. These chargers are 480 volt / 3 phase / 18 amps each. Both load panels are approximately 20 to 30 feet from the chargers.

The client has acquired new chargers to replace the existing ones. However the new charging station will be in a different location in the warehouse. The existing chargers will be removed and the electrical installation supplying them eliminated. My plan is to install one new load panel at the new location for all the chargers. According to my rough distance calculation, the feeder for the new load panel will be approximately 600 feet away from the switch-gear.

Since the chargers will be used for 3 hours or longer and will be used all at once, I'm calculating it as a continuous load. (22.5 amp X 20) which gives me a feeder load of 450 amps. I was thinking of using 2 sets of 350 kcmil in parallel.
My question is whether there is any provision in the code concerning demand factors for fork lift battery chargers. I don't want to price this higher than it needs to be and lose the bid.
I have not been able to find any articles in the NEC specifically pertaining to this installation. Likewise I haven't been able to find any prior posts at this forum.

 

[Barbqranch]

I don't know about these chargers, but our charger (45 amp, 208 Volts 3 phase) draws the full current for less than 2 minutes, then drops off. I would not at all consider it a continuous load for design purposes.

 

[augie47]

Likewise, I don't see a need to figure the entire load as continuous. Most chargers I have seen will NOT draw the maximum load for 3 hrs continuously. 400 amps is a good "breaking point" for gear, etc and I would probably use that noting you have provides a bit of a cushion for "future".

 

[mike_kilroy]

I don't know about these chargers, but our charger (45 amp, 208 Volts 3 phase) draws the full current for less than 2 minutes, then drops off. I would not at all consider it a continuous load for design purposes.

Our 45a 220 charger output 40a for a good 30 min! Sometimes longer. Guess our guys run it down more than your guys... 36v golf cart with new Trojans outputs the 20a charger nearly 2 hour at full 20a... I would not want to undersized a customer too much here...

Sent from my SM-G900V using Tapatalk

 

[ArtZat]

Likewise, I don't see a need to figure the entire load as continuous. Most chargers I have seen will NOT draw the maximum load for 3 hrs continuously. 400 amps is a good "breaking point" for gear, etc and I would probably use that noting you have provides a bit of a cushion for "future".

I was unable to find any information from the manufacturer concerning the amount of current the charger draws while charging.
If I take the 400 amp figure to the building department when applying for a permit, I'm worried that I won't be able to back that up when they ask for calculations to substantiate how I arrived at that figure.

 

[ArtZat]

I don't know about these chargers, but our charger (45 amp, 208 Volts 3 phase) draws the full current for less than 2 minutes, then drops off. I would not at all consider it a continuous load for design purposes.

Is there any reference in the code that allows industrial battery chargers to be calculated at only 100% load?
I'm not trying to put you on the spot, I'm just frustrated that I can't find it in the code.:?

 

[iwire]

Is there any reference in the code that allows industrial battery chargers to be calculated at only 100% load?

Not really, the only guidance is the definition of continuous load in article 100.

I'm just frustrated that I can't find it in the code.:?

You will be much more frustrated if you get the job by under sizing the feeder and it trips.

 

[Dennis Alwon]

Here is the article

625.42 Rating. The equipment shall have sufficient rating to
supply the load served. Electric vehicle charging loads shall be
considered to be continuous loads for the purposes of this article.
Where an automatic load management system is used, the
maximum equipment load on a service and feeder shall be the
maximum load permitted by the automatic load management
system.

 

[ArtZat]

Here is the article

Actually I checked article 625 before posting here.

Article 625.2 Definition "Electric Vehicle........For the purpose of this article.......industrial trucks.........are not included."

I'm not sure how else to interpret that, but it seems that it doesn't apply to the installation in question. It would be difficult to argue with the inspector contrary to what is written in the code. Otherwise I would've said, there's my answer, case closed. I'm surprised that there wouldn't be something specifically pertaining to electric fork lifts and battery chargers in the code. There are a lot more of them then there used to be, and I'm sure they will increase since people are concerned about air quality in buildings.