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Kevin, Licensed Electrical Contractor
Category: Electrical
Satisfied Customers: 3533
Experience:  30 years Licensed Electrical Contractor in Illinois, Adjunct College Electrical Instructor, Former Electrical Inspector, Diploma: Digital Electronics, FCC Technician License
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I have an old Nutone intercom system that is about 20 years

Customer Question

I have an old Nutone intercom system that is about 20 years old. I want to remove each unit and replace it with a nicely made INSERT that will cover the big hole. I also want to make these charging stations for cell phones etc. Now here is the 64K question. Do you think I can use the existing intercom wires (even bunched) so I can send low This would be for charging devices only. It is a very large house. You cannot guess. You would need to be sure. I am not located at that house at present so I cannot open one up to inspect the wires or take a photo for you. Thanks,

I think this is it:

Submitted: 9 months ago.
Category: Electrical
Expert:  Kevin replied 9 months ago.

Hello and welcome to Just Answer. My name is ***** ***** I will be happy to assist you with your electrical question.

1) Intercom systems utilize low voltage cabling from the master to remote stations. Therefore, you cannot re-use low voltage cabling for either 120V USB charging devices or for 120V wall receptacles.

2) To wire up such charging devices, the branch circuit conductors need to be protected by either a 15 or 20 amp circuit breaker along with the correct conductor size to match the or 12 AWG copper.

If you have any additional questions, just let me know and I’ll be glad to answer them for you.

Otherwise, don’t forget to rate me before you log Off.


Customer: replied 9 months ago.

Kevin, I am aware of all of this. I am asking why the low-voltage current cant be sent to each location?

Expert:  Kevin replied 9 months ago.

1) Minimum conductor size for 120 volt electrical circuits is 14 AWG copper or 12 AWG aluminum within the National Electrical Code.

Low voltage cable is smaller than 14 or 12 AWG wire and can't support the current.

2) Charging station devices (USB's and/or receptacles) are high voltage and not low voltage.

Customer: replied 9 months ago.

Kevin please turn this overt to another electrician. You are not understanding that I want to lower the voltage BEFORE it gets send out through the intercom wires. USB is 5v..Thanks R

Expert:  Kevin replied 9 months ago.

Yes you are correct. USB's are 5 volts, but the USB device requires 120 volts to power it.

Refer to the link shown below and see the voltage specs............shows 120 volts:)

Can't use low voltage intercom wires or cabling for a 120 volt USB device. Good way to create a fire if you choose to do this:)

I've opted out of the question...........good luck.

Customer: replied 9 months ago.

I will tip $20 if i cam get this answered properly. Let me say again to anybody talking this question. 120 volts will be used at the base unit of the Intercom system. There it will be (properly) reduced down to 5v at a high enough amperage to power many devices. Once stepped down to 5V I want to distribute this 5v around the house using the existing Intercom cables. thanks