votage drop on control circuits

[codegreen]

My first time.
Here is a question. What is the allowable voltage drop for loads that are connected from an industrial control panel? Eg.solenoids banks that are actuated from PLC outputs etc?.We use #18 or #16 AWG. and a voltage drop of 10%.
Rule 8-102 of CE code,says a total of 5%.
The voltage drop depends on the length of conductor,load and other things. Is there a loading factor when designing circuits and breakers in control panels for control circuits according to CE code?
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[codegreen]

Thanks for the reply .
1. Yes my question is entirely relating to chapter 16. My mistake. The voltages are mostly 24VDC.DC control circuits basically.
2. Since you pointed out to the circuit class, I do have a question in that too. We use transformers from 3KVA and more as a supply source for the above. There is no mention as to which circuit class it belongs to because it is over 1000VA and almost always it feeds a 110VAC to 24VDC regulated power supply in our case.The only reason I think it is a class 2 circuit is because of rule no.16-200(iii). Which accepts any electronically controlled current limiting charecteristics to 100VA. I am not quite sure if they do this function or not. I am only assuming
things. Any input and opinions on this regard is welcome.

[neil seidner]

I have used many 120VAC to 12VDC power supplies that automatically interrupt the circuit when a short is present, however I can't recall what VA it was set at or if it was a class 2 device. If you read 16-200(b) carefully, a "class 2" device is not required if the circuit is fused at less than 100VA.

[neil seidner]

If you are using #16 and #18, then it sounds like it is either a class 1 or 2 circuit. If it is a low voltage circuit then its a question of whether the scope of section 8 includes class 1 and class 2 circuits (8-000,(a)). If it is not included in the scope, then 8-102 would not apply, and the conductors would have to be sized based on section 16 (which makes no mention of a voltage drop requirement).

If it is a 120 Volt circuit, then I don't see how you could use the smaller conductors and have a 10% Voltage drop.

[codegreen]

I can not afford to have 100VA protection when the transformer is 3KVA and up. The device it is feeding is a regulated power supply of 110VAC to 24VDC. I am still at a loss to find out if it is a Class1 or class2 circuit.
Thanks in advance for replies.