electrical wiring for centralite?? (litejet)

[pjwinstalls]

i am installing a centralite system (litejet). I am connecting 20 amp breakers to each dimmer module. You can connect 4 loads to that with no single load more than 8 amps......... do i have to run 12/2 to the lights from there as well or 14/2?

 

[rfdesq]

Check your local code, but 12 gauge wire handles 20 amps, 14 gauge wire handles 15 amps. Generally, putting a 14 gauge wire on the output of a 20 amp breaker would be dangerous and a code violation.

 

[pjwinstalls]

The output from the breaker to the dimmer module would be 12 gauge. From the dimmer module to each load would be 14/2 ....no load would be over 8 amps. This is what i am not sure about....

 

[rfdesq]

I think you are looking strictly at the rating for the dimmer module without looking at the big wiring picture. Let me see if I can explain it a little differently. The wire going to the breaker is the proper size 12 gauge for a 20 amp breaker. If you use 14 gauge wire down the line from the breaker you could exceed the amperage of the 14 gauge wire which is only 15 amps before tripping the 20 amp breaker. Result could be melting wire, arcing, fire, all not good.

 

[pjwinstalls]

ok thanks a lot!

 

[pjwinstalls]

Do you know if it is true that your not supposed to load a breaker more than 80% of its rating..... So if a breaker is 15-amp the load connected to it cant be more than 12 amps????????

 

[rfdesq]

I've not heard that. I'd bet a beer that most houses are not wired that way. Simple test is to plug something into each outlet and turn on every light switch. I'd bet you blow every circuit breaker in the house. I think the rationale is that you are not going to be using every outlet and every light in the house all at once.

 

[kayemsi]

Strictly looking at the 8 amps from the dimmer module to the load, 14 gauge should be fine. 20 gauge wire is derated to 7.5 amps in aircraft wiring, so 18 or 16 should be acceptable and 14 is more than enough.

Only things is if something went wrong in the dimmer module and somehow all 20 amps got down the wire to the load. Not sure if that is possible with the dimmer module design.

 

[mlaz]

As a licenced electrician I am concerned about some of the post in this thread. No offence intended to anyone, but yes we do use the 80% rule for all circuits. The reason we do this is because the Nathional Electric Code required us to have each yoke count as 180 watts of power in our calculations. This will not cover all items such as vacuum cleaner, portable heaters, glue guns, and other large current drawing devices. therefore as a rule of thumb yes we only load a circuit to 80% of its calculated load. (lights count as the maximum wattage rating of the fixture to be hung.....)

Now to the original question can you reduce the wire gage going to a device on a 20 amp circuit. No, unless you add a current limiting device to protect the wire downstream of the the smaller size this is not permissable. This would be the same as starting a circuit in 12 gauge, but as you get farther away from the breaker box or downstream of the first device you start to lower your cable size.

If 20amps are available then a conductors on that circuit must be rated for such.

sorry for being so wordy, but hope this helps

 

[mikecreid]

I work for Centralite, so here is the factory info on Litejet. The panel is rated at 72 amps for 24 loads, so the average load can be 3 amps. There are 6 dimmer boards with 4 dimmers on each board. Each board has 1 line feed and 4 outputs.

So if you have a 20 amp breaker feeding a dimmer board, you first derate this 20% so you have 16 amps to work with. Any 1 dimmer can handle a maximum of 8 amps, with the remaining 8 amps divided across the remaining 3 dimmers.

Remember that is you feed a dimmer with 12 gauge wire, you have to run 12 gauge wire to the loads. Most electricians use 14 gauge wire for lighting loads. If you use 14 gauge wire, you have 15 amps derated by 20% so the effective current is 12 amps, or 1440 watts. We use 120 VAC for the ohms law equation. 120 VAC * 15 amps = 1800 watts, * 80% to get 1440.

The reality of a typical home is that there are many small lighting loads, at 100-200 watts max, so the average of 3 amps per load or 360 watts is usually sufficient. And since any one load per dimmer board can be rated at 8 amps, or 960 watts, you have some wiggle room

Centalite also manufactures a larger capacity system called Elegance, and a new wireless Zigbee based system call Starlite

 

[jlehnert]

Welcome both mlaz and mikecreid.

Glad for the additional manufacturer and professional input. There are several other electricians (and manufacturer reps) that hang around the board, but that doesn't mean that someone catches all the goofs, all of the time.

Stick around, and hopefully someone will be able to help you out in THEIR field of expertise.