Electrical Wiring for Light Switches
By Dave Rongey - Summary:
The Difference Between Commercial and Home Electrical Wiring: In this example a commercial medical building has a 277/480volt system.
Light Switch Wiring in a Commercial Building
Electrical Question: How do I wire two separate lights and switches in one supply junction box?
- I have a junction box with a top conduit that goes to one switch and one light.
- The left side top conduit is the power supply coming from another junction box.
- The bottom left side of the junction box has a conduit for a light and one switch.
- On the right side are two conduits that are controlled by switch #2 which is wired through the bottom conduit.
These are Two Separate Rooms with Two Separate Switches
- I need to know how to wire the orange wire which is confusing to me because that wire is coming from light fixture #1.
- I think the wire should be black.
- There are two wires with black tape and I need to know what they are used for.
This is a Commercial Medical Plaza in Laguna.
I really appreciate your help with this, and why it is wired this way.
This electrical question came from: Chris, a Handyman from Laguna, California.
Thanks for your electrical question Chris.
The Difference Between Commercial and Home Electrical Wiring
IMPORTANT: Here in the USA, commercial electrical wiring is not the same as home electrical wiring.
- For Example:
- The voltage for most commercial light fixtures is typically 277 volts, which is not the same as the home electrical voltage for lighting which is 120 volts.
- Since the voltage is different, the standard used to identify the wires is different as well.
A Warning about Commercial Electrical Systems
- In the example of this electrical question, a handyman working in a commercial medical building which has a 277/480volt system poses a higher risk and danger of electric shock and arc flash hazard because of the higher voltage. Therefore for your own safety, I do not recommend that a handy-person perform electrical work in a commercial environment unless you are fully experienced and knowledgeable.
- Working with electricity, especially higher voltage requires a Qualified Licensed or Certified Electrician.
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