24 VDC Distance

Tim Ganz

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• Feb 21, 2011

• #1

What is a safe distance to run 24 vdc wiring?

From the PLC to pilot lights / Pushbuttons and starters?

Is 300 - 400 feet excessive?

 

PeterW

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• Feb 21, 2011

• #2

You would need thick wires.

Can you install remote IO?

 

BryanG

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• Feb 21, 2011

• #3

For inputs check the PLC manufacturers spec sheet. Looking at Siemens s7-200 PLC they give 300 metres unshielded, 500 metres shielded (you may want to reduce this in a very noisy environment). For the indicators / pilot lights you need to look at the current required for the device, the switching frequency and what danger there may be if you get a false indication.

Bryan

 

albertabound

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• Feb 21, 2011

• #4

Tim Ganz said:

What is a safe distance to run 24 vdc wiring?

From the PLC to pilot lights / Pushbuttons and starters?

Is 300 - 400 feet excessive?

Click to expand...

Depends on the acceptable voltage drop. Code typically calls for 5%(?), so you would do your calculations based on current requirements and size wire accordingly. If your running a noisy environment, AC I/O might be a better choice.

 

Tom Jenkins

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• Feb 21, 2011

• #5

Try this site:

http://www.powerstream.com/Wire_Size.htm

This is a fundamental Ohm's Law question.

 

Tim Ganz

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• Feb 21, 2011

• #6

Is Ohm's law the same for AC and DC?

 

OZEE

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• Feb 21, 2011

• #7

Tim Ganz said:

Is Ohm's law the same for AC and DC?

Click to expand...

Every time....

 

Mickey

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• Feb 21, 2011

• #8

Tim Ganz said:

Is Ohm's law the same for AC and DC?

Click to expand...

And just so you don't forget.

http://www.etgiftstore.com/items/al...s-basic-ohms-law-watch-141dc-141dc-detail.htm

 

TimWilborne

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• Feb 21, 2011

• #9

That's a nice watch!

 

Mickey

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• Feb 21, 2011

• #10

TWControls said:

That's a nice watch!

Click to expand...

Just make sure the boss sees this thread, you may get one for X-Mas.

 

TimWilborne

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• Feb 21, 2011

• #11

My boss? He has no concept of time...oh wait, I am my boss!

 

Mickey

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• Feb 21, 2011

• #12

TWControls said:

My boss? He has no concept of time...oh wait, I am my boss!

Click to expand...

Not that boss the real boss. Are you married?

 

TimWilborne

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• Feb 21, 2011

• #13

Well yes, but if I wore a watch she would expect me to be on time

 

JeffKiper

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• Feb 21, 2011

• #14

I like X-Mas gifts guys. I am always running a 100 MPH going nowhere and running late.

 

apuskas1986

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• Feb 22, 2011

• #15

Tim Ganz said:

What is a safe distance to run 24 vdc wiring?

From the PLC to pilot lights / Pushbuttons and starters?

Is 300 - 400 feet excessive?

Click to expand...

300-400 feet isn't excesive, but I would advise you to use relay outputs and inputs for the PLC, and also while wiring such a long distance it's recomended that DC wires are vertical to AC wires, or that they have a good shield (ground the shield on ONLY one end of the cable).