circuit for small baterry chrgers

[FREEBALL]

I am currently asked to install a circuit for small battery chargers for portable radios and electric litters. There will be 6 chargers for litters and 10 chargers for portable radios. The input power for the litter batterys will be 1.2 amps and 0.9 amps for the portable radios. Is there anything I should look into or can I just size accordingly at 80% for the total load and plan on 20 AMP circuit. I can not find much code wise for these small chargers. I am concerned about heating with the chargers being so closed together. I am installing a surge protector for the panel that feeds these but should I derate more than the typical 80% .

thanx
jeff

 

[ActionDave]

Although the CMP's keep moving the NEC farther from the it's stated purpose that it is not a design manual this is an example of when it is not one.

Sounds like all you need a properly wired circuit that is adequate for the load and you are good to go.

What is an "electric litter"?

 

[FREEBALL]

battery operated ambulance cot/litter thanx for the reply

 

[kwired]

Also consider the reality that these chargers will hardly ever draw their full rating, unless you make it a habit of starting a charging session with all units at same time with fully discharged batteries connected to every unit.

I have seen many times where a whole slug of power tool chargers were all on same 15/20 amp circuit or even many notebook computers in a school all plugged into same circuit and never overloads the overcurrent device - this is because few if any are drawing full rated current - and if so, it is not for very long.

 

[don_resqcapt19]

Given what they are for, I would use at least two circuits. That way a single breaker that has tripped or been accidentally shut off does not leave all of your radios with dead batteries.

 

[kwired]

Given what they are for, I would use at least two circuits. That way a single breaker that has tripped or been accidentally shut off does not leave all of your radios with dead batteries.

I would agree especially since this is likely equipment that may need to be ready for immediate emergency use.

 

[winnie]

If the chargers plug in separately and you provide a separate receptacle for each charger, then you may have to increase the size of your circuit to provide 180VA per receptacle.

As a design issue (not a code requirement) I agree with Don's point about using two circuits. Another design trick (not a code requirement and probably not relevant here) for 'background' loads is to incorporate a limited but very obvious load onto the same circuit, for example a nearby light. (I believe that Canada used to require a hall light on the smoke detector circuit.)

-Jon

 

[FREEBALL]

Thankyou I wasn't thinking in that direction but yes we wouldnt want 1 circuit killing all chargers great idea thanx again.