Electrical Issues from garage

[JackAndy]

I was trying to run a CAT5 cable from the garage to the house. There is a 240v circuit that runs in conduit underground and a circuit for the garage outside lights. So you flip a switch in the house and the lights on the garage turn on.

With the switch on, the voltage for those garage lights measures 118 volts. I flipped the switch off and it measured 15 volts. I thought that was funny because the switch is off. Is that an electrical issue? I asked an electrician and he said on some old buildings, they didn't polarize the wiring and the neutral could be switched with the current wire. So he said you could test for polarity with a plug in polarity tester. Sometimes the lights in the house dim when some load like the A/C or refrigerator start. Is that caused by the polarity being flipped?

So what happened next made me think there is an electrical problem. I pulled the CAT5 cable through the conduit by taping it to the end of the wire for the garage lights. Then I taped the garage lights wire back to the middle of the CAT5 so I had them both pulled through and enough length on either side to hook them up.

When I plugged the CAT5 cable into the router, the wifi on the router just shut off. I never saw the lights on the router flicker and I don't think I accidentally unplugged it. The wifi lights just shut off. I went into the management website and found that the radio for wifi was disabled. So I re-enabled it and the wifi started working again and has been working. Is this caused by some voltage difference between the device in the garage and the router in the house?

 

[rlitman]

...Is this caused by some voltage difference between the device in the garage and the router in the house?

No. Ethernet uses a balanced setup that is isolated from such a voltage difference. Unless you ran SHIELDED ethernet. But then if there was a difference in ground potential, it would probably spark when you plugged it in.

Is the switch in the house lit? Lit switches allow some voltage to pass through the circuit.

 

[wyliesdiesels]

Cant run communication cable in the same conduit as line voltage cable.

The 15v youre seeing is phantom power. Put a load on it and it will go away.

Lights breifly dimming during AC startup is normal. Motors have whats called in-rush current that is 4-8x the FLA current, during startup. So your compressor could be pulling close to 100a while starting...

 

[rlitman]

Cant run communication cable in the same conduit as line voltage cable.

The 15v youre seeing is phantom power. Put a load on it and it will go away...

Communication wire in the same conduit as line voltage cable CAN be run, but it needs to have an insulation rating appropriate for that conduit system. I see 300V and 600V Cat5e cables are available, though I've never actually encountered one. Anyway, just because you can do it, doesn't mean you should.

15V seems like way too much to be phantom power. Even if he's measuring with a DMM. But it's perfectly normal for a lit switch, or maybe he has some other issue, like a lack of grounding.

 

[JackAndy]

No. Ethernet uses a balanced setup that is isolated from such a voltage difference. Unless you ran SHIELDED ethernet. But then if there was a difference in ground potential, it would probably spark when you plugged it in.

Is the switch in the house lit? Lit switches allow some voltage to pass through the circuit.

Thanks. I'm not sure what a Lit switch is. Its not a dimmer if thats your question.

Cant run communication cable in the same conduit as line voltage cable.

The 15v youre seeing is phantom power. Put a load on it and it will go away.

Lights breifly dimming during AC startup is normal. Motors have whats called in-rush current that is 4-8x the FLA current, during startup. So your compressor could be pulling close to 100a while starting...

Thanks. I guess I'm not sure how else to run the data line from the garage though because its a detached garage. What you're saying is that I'd have to dig another trench and setup another conduit.

Communication wire in the same conduit as line voltage cable CAN be run, but it needs to have an insulation rating appropriate for that conduit system. I see 300V and 600V Cat5e cables are available, though I've never actually encountered one. Anyway, just because you can do it, doesn't mean you should.

15V seems like way too much to be phantom power. Even if he's measuring with a DMM. But it's perfectly normal for a lit switch, or maybe he has some other issue, like a lack of grounding.

Its CAT5e so I'm sure its nothing fancy. I could take it out of the conduit just as easily. My guess is the only other option at that point would be one of those Ethernet switches that uses power line carrier signals to transmit data over the 120v wiring. I'm transmitting video data though so I'd like to keep a high data rate if possible.

 

[penusai]

They also have direct burial CAT5e/6.

 

[penright]

I am not a licensed electrician, maybe one will correct me, it was my understanding there a class 1,2,3 devices or something. I don't know which is which. But, even if the wire is rated and may be allowed to be in the conduit, because of the device that is being used, it can not be ran in the same conduit in your example. Someone working on a network device, say recremping the RJ-45, has an expectation the voltage will not be more than the devices they are working on. Which could happen if somehow they got shorted inside the conduit somehow.

Again, I could be wrong but I don't think you can run networking wire in conduit that has load (120v +) carrying voltage. And has been said you do not want to do it anyway.

 

[mike93lx]

You can't have two feeders, so you ahould abandon/remove the lighting circuit anyway and switch to a wireless switch. That frees up the conduit for cat5 and makes the 15v a moot point.

 

[rlitman]

Thanks. I'm not sure what a Lit switch is. Its not a dimmer if thats your question...

No, an illuminated switch. Something that glows when it is off. They leak a little current to run the neon inside.

 

[ard]

Thanks. I guess I'm not sure how else to run the data line from the garage though because its a detached garage. What you're saying is that I'd have to dig another trench and setup another conduit.


Its CAT5e so I'm sure its nothing fancy. I could take it out of the conduit just as easily. My guess is the only other option at that point would be one of those Ethernet switches that uses power line carrier signals to transmit data over the 120v wiring. I'm transmitting video data though so I'd like to keep a high data rate if possible.

WiFi, Can run video data, easily.

Also, based on your post it seems this conduit is not the service to the garage, but is a switch leg for a light.

You could convert the conduit into a low voltage conduit, and place a switch in the house that controls the light via [not 120VAC]. like zwave, x10, wifi, etc.

Unless there is also more in the conduit. If so, I'd do wifi.