First Breaker or contactor

[Electriman]

Dear Friends,

I am facing an application that I need to have a lighting contactor for multiple loads after a lighting transformer. I know that we have to put a protection on the secondary of the transformer. My question is can I put a lighting contactor right after transformer secondary and then place the breaker for protection? I feel this is wrong but I would like to support my feeling with some legitimate states of NEC code or other approved standards.

 

[raider1]

Welcome to the forum.

The transformer secondary conductor rules found in 240.21(C)(2) and (6) (The 10' and 25' secondary rules) require that the transformer secondary conductor terminate in an overcurrent device or equipment containing an over current device.

Chris

 

[raider1]

I should ask is this a low voltage lighting systems that would comply with Article 411?

Chris

 

[kwired]

Why not put the contactor in the transformer primary circuit? Then you have no transformer losses when not using the lights, also if a step down application you can use a lower amp rated contactor.

 

[Nom Deplume]

Why not put the contactor in the transformer primary circuit? Then you have no transformer losses when not using the lights, also if a step down application you can use a lower amp rated contactor.

Good solution ^

 

[Electriman]

I should ask is this a low voltage lighting systems that would comply with Article 411?

Chris

Yes. This is a low voltage 208/120 VAC lighting. and I am considering to place the contactor in transformer primary but the problem here is how to feed the contactor coil and photocell.

 

[Electriman]

Why not put the contactor in the transformer primary circuit? Then you have no transformer losses when not using the lights, also if a step down application you can use a lower amp rated contactor.

I am considering to place the contactor in transformer primary but the problem here is how to feed the contactor coil and photocell.

 

[fmtjfw]

I am considering to place the contactor in transformer primary but the problem here is how to feed the contactor coil and photocell.

The coil circuit need not be interconnected in any way with the switched circuit. If you need a lower voltage for the coil either find it some were else r use a control transformer to feed it.

 

[kwired]

If primary is 480 with 277 available use a 277 volt photo cell and 277 volt contactor coil, otherwise you may need a control transformer if using other control voltages.

 

[Electriman]

That seems to be the way to go. Thank you all.