Forklift charger

[Cletis]

If you run 4-10's thhn in some 3/4" sealtight approx 8ft from a charger right to the panel on a 50 amp OCP 3 pole breaker and have internal fuses in unit at 30 amps per would this be ok per NEC ?

 

[mgookin]

Are you charging lead acid batteries?

 

[Cletis]

Not sure? I think they are. How would that make a difference on OCPD rating though ?

 

[jimdavis]

In my opinion that would not be code-compliant. I see the internal fuses in the forklift charger as supplementary OCP. The wiring from the panel to the charger is a branch circuit and the conductors need to be protected at their ampacity.

 

[Cletis]

In my opinion that would not be code-compliant. I see the internal fuses in the forklift charger as supplementary OCP. The wiring from the panel to the charger is a branch circuit and the conductors need to be protected at their ampacity.

I was afraid of that. I was hoping the panel disconnect could be construed as feeder protection and fuses would be branch circuit protection but maybe i am wrong. Below is pic of charger

 

[mike_kilroy]

I was afraid of that. I was hoping the panel disconnect could be construed as feeder protection and fuses would be branch circuit protection but maybe i am wrong.

and what happens if one of the #10 wires get shorted to ground? See why it is not compliant? Your 30 amp fuses will do nothing to prevent the garage from burning down.

 

[iwire]

and what happens if one of the #10 wires get shorted to ground? See why it is not compliant? Your 30 amp fuses will do nothing to prevent the garage from burning down.

What size EGC is required to be run with a 50 amp circuit?

 

[ActionDave]

Same as one for a 60A circuit.

 

[iceworm]

and what happens if one of the #10 wires get shorted to ground? See why it is not compliant? Your 30 amp fuses will do nothing to prevent the garage from burning down.

Yes - I agree the install is not code compliant. However:

In this case, it blows the 50A fuse - highly likely inside the conductor damage curve. The fuse does not limit the load. The design does.

For the #10 to be in trouble, the fault would have to draw more than 30A and less than 50A - and be on the upstream side of the 30A fuses.

Again - not per code. I just don't see it as being particularly dangerous. No authouity - just an opinion.

ice

 

[iwire]

Yes - I agree the install is not code compliant. However:

In this case, it blows the 50A fuse - highly likely inside the conductor damage curve. The fuse does not limit the load. The design does.

For the #10 to be in trouble, the fault would have to draw more than 30A and less than 50A - and be on the upstream side of the 30A fuses.

That was what I was getting at with my comment about the EGC.

I agree, not compliant but not going to burn up on a short.

 

[rlundsrud]

Ok, I will play the Devils advocate on this one. How is this different from an AC unit that has a 30 amp breaker with #12 or #14 wire. I assume it is because the codes for motors have allowances for inrush current but insofar as the conductor protection there isn't any difference. The motor OVL is protecting the conductor as the fuses would be in the OP's proposed scenario.

 

[GoldDigger]

If the fuses can provide overcurrent (low amp) protection and branch circuit short and ground fault protection you could have a legal tap conductor installation.
If the fuses can only be counted as supplemental OCPD, then no matter how similar it is to the motor scenario, it is not code compliant.

 

[rlundsrud]

If the fuses can provide overcurrent (low amp) protection and branch circuit short and ground fault protection you could have a legal tap conductor installation.
If the fuses can only be counted as supplemental OCPD, then no matter how similar it is to the motor scenario, it is not code compliant.

So would the OP's suggested method comply as a tap conductor? If not could it be made to comply and if so by what methods?

I only ask these questions to further my understanding, not to undermine other members suggestions. Thanks for the info.

 

[Cletis]

All I do know is this. From looking at many charts in running 50amp through #10 thhn in conduit under 10ft it would take like a year or more continuous to actually cause any breach in the insulation. Please correct me if I'm wrong as I will end the thought forthwith. Furthermore, with it being a non continuous load, a running load of only 22 amps, and fuses to thermally cutoff I don't see that there would ever be close to a problem with this setup. If it's against code or not I have no idea.

 

[ActionDave]

Ok, I will play the Devils advocate on this one. How is this different from an AC unit that has a 30 amp breaker with #12 or #14 wire. I assume it is because the codes for motors have allowances for inrush current but insofar as the conductor protection there isn't any difference. The motor OVL is protecting the conductor as the fuses would be in the OP's proposed scenario.

Motors have overload protection built in so you only need ground fault and short circuit protection at the source. A ground fault is going to generate a thousand amps for a moment and then the over current is going to trip.

Motors take in a big gulp of amps right at start up but only draw a fraction of that inrush current when they are running so allowing smaller conductors on a larger breaker or fuse is reasonable, safe, and cost effective.

 

[Electric-Light]

That's clearly a 3 phase rectifier bridge, 6-pulse charger.

What if it single phased and the load level is such that it went to a bit above 30A for a long time? Absent some sort of termination, it will continue to charge as single phase 2 pulse charger, but pulling more current.

Those fuses are probably fast blow type current limiting type meant to protect the diodes in case one of the output leads are grounded.

 

[kwired]

Your overcurrent protection levels and locations are compliant, you do have a feeder tap properly protected and a branch circuit properly protected.

What may not work is you likely don't have a fuse/switch/fuseholder or some combination of those that is rated for branch circuit disconnecting means? I've been looking and haven't found a code to cite just yet but I think there probably is something somewhere along this line of thinking.

Maybe the answer is in 240.24(A)? But I guess that still hinges on whether the "feeder breaker" can be considered the disconnect required in 240.40 for those fuses. Typically a fused disconnect or a switch immediately adjacent to the fuses is what this section is after - other opinions??

 

[iwire]

Your overcurrent protection levels and locations are compliant, you do have a feeder tap properly protected and a branch circuit properly protected.

I disagree there, the tap rules require the taps terminate at an overcurrent device. In the OPs case they terminate at the battery charger unit.

 

[kwired]

I disagree there, the tap rules require the taps terminate at an overcurrent device. In the OPs case they terminate at the battery charger unit.

and they terminate at an overcurrent device within that unit. Put a fused disconnect between them and you still have to enter the switch enclosure before hitting the overcurrent device - kind of the same thing. I am not saying this install would be NEC compliant - but have not seen a clear answer yet that prohibits it nor have I seen one that clearly allows it.

What I have for questions so far though-

Doesn't a branch circuit require a disconnecting means? I haven't yet found a clear answer to that question either

If those fuses are the end of the feeder/beginning of the branch circuit - what is the branch circuit disconnecting means if one is required?

The fuses do require a disconnecting means according to 240.40 - is the feeder breaker only 8 feet of conductor away allowed to be this disconnect?

 

[iwire]

and they terminate at an overcurrent device within that unit.

The unit is listed as a charger, not an overcurrent device. IMO Those fuses inside do not exist to the NEC.