3 phase 208v lift charger

[conrad3]

I do mostly residential work; and therefore, I rarely work on 3 phase circuits. However, I have a customer who needs a forklift charger installed for a single lift that is rarely used in a small factory. The max amp rating on the nameplate of the charger is 25 amps at 208v/3 phase.

I was planning on running #10 from a 3 pole 30A breaker in the panel to a 30A twist lock receptacle right next to the panel in EMT. Then run a 10/4 SOOW about 8 feet from the receptacle to the charger. This is a charger not a motor, so no need to figure 135% for continuous load?

Apparently 10/3 SOOW is rated for 30 amps but 10/4 rated only for 25. Perhaps use 8/4 SOOW instead?

We are on 2008 NEC here. I don't see how this could be wrong, but just wanted to be sure.

 

[Jraef]

It's de-rated because there are 3 CCCs in the 10/4 cord, so if the SOOW is important, then yes, you would need #8. But why the SOOW? You need the input of the charger to be flex cable? The output to the forklift, sure, but why not just mount the charger and hard wire it right to the breaker?

 

[conrad3]

It's de-rated because there are 3 CCCs in the 10/4 cord, so if the SOOW is important, then yes, you would need #8. But why the SOOW? You need the input of the charger to be flex cable? The output to the forklift, sure, but why not just mount the charger and hard wire it right to the breaker?

Ahh... I see. More CCCs=higher temperature. Thanks Jraef.

I figured if the 10/4 is rated for 25A and the charger is also 25A I'd be ok, but l suppose I'll use 8/4 just to be on the safe side.

This facility has very limited space available. Because of the fact that they only charge their lift a few times a year, they want to keep it on a pallet and move it in place when they need to use it. I did offer them the option to wall mount it, but they are planning on moving to a bigger facility in the near future and wanted a safe but temporary option.

 

[kwired]

If charging cycle lasts for less then 3 hours then it is not a continuous load.

Also keep in mind current level probably does drop as the battery charge level increases - some of this depends on the design of the battery and charging system though.

 

[infinity]

Ahh... I see. More CCCs=higher temperature. Thanks Jraef.

I figured if the 10/4 is rated for 25A and the charger is also 25A I'd be ok, but l suppose I'll use 8/4 just to be on the safe side.

This facility has very limited space available. Because of the fact that they only charge their lift a few times a year, they want to keep it on a pallet and move it in place when they need to use it. I did offer them the option to wall mount it, but they are planning on moving to a bigger facility in the near future and wanted a safe but temporary option.

Have you taken a look at Article 400 for flexible cord ampacities?

 

[publicgood]

Do we know the battery type being charged? Assuming VRLA, it takes about 6 hours for IEEE considered recharged (current stabilize within 10% if I recall correctly). According to the NEC, this is longer than 3 hour and thus, continuous. The circuit and OCPD should be based on 125%.

10/4 is 3 CCC plug equipment ground. There is no derate according to article 400. The white conductor needs to be re-identified as a phase conductor. 35A branch breaker (can't round down since serving receptacle). Less than 100A, so 60C conductors in conduit is #8 single conductors. Then 8/4 SOOW with a 40A rated twist lock receptacle.


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[drcampbell]

... current level probably does drop as the battery charge level increases - some of this depends on the design of the ... charging system ...

With an old-fashioned charger -- with a large 60-Hz transformer and primitive or no charge-rate controls -- this is true.
With a modern charger -- with a switch-mode converter, a small, high-frequency transformer and multiple different modes (called "4-step", for example) the battery charge current remains constant throughout most of the charge cycle and the battery voltage increases slowly. The AC input current actually goes up during the bulk-charge step.

 

[zbang]

Because of the fact that they only charge their lift a few times a year, they want to keep it on a pallet and move it in place when they need to use it.

Depending on the type of batteries (and age & storage conditions), that can be a recipe for failure. What do they do when the batteries are dead and they can't move either the lift or the charger? (Not exactly your problem, but it could be theirs.)