Routing Cable TV with Electric Wires in one tube

Cybergrizzly · 17-03-2008, 16:00

Due to pre-existing conditions in my house, I want to route or install the incoming cable tv coaxial cable in one 1-1/4" diameter PVC pipe along with 2 electric wires (120 volts) feeding a simple external fluorescent light.

Question: Will electricity or whatever magnetic field that can be produced from 2 electric wires affect the cable tv or internet signal in a coaxial TV cable ?

**Graham M** · 17-03-2008, 16:19

Most likely, yes.

bmxbandit · 17-03-2008, 16:27

Given that it's only likely to be a couple of amps running through the electric cables, the magnetic field would be only a couple of gauss. I'm not convinced it would be a problem, but I can't say it definitely wouldn't...

**Rob** · 17-03-2008, 16:36

As far as I know wires that carry different voltages should not normally be routed through the same duct channel. You can have a multicore duct or trunking to keep things separate. It's a safety thing in case of a powered wire developing some sort of fault and coming into contact with an unprotected wire.

Cybergrizzly · 17-03-2008, 16:44

I called the cable company and the customer support lady said she had consulted the matter with one of the technicians and that they had said it would not be a problem. I want to be sure before doing anything. Electric wires will be 12 gage (one positive lead and one negative lead), 120 volts feeding a simple 40 or 60 watts flourescent lamp.

---------- Post added at 16:44 ---------- Previous post was at 16:40 ----------

Coaxial cables are shielded as well as 12 gage electric wires. That is not enough ? I could purchase a single electric cable that is shielded and bears the two wires inside. Would this help ?

Draby · 17-03-2008, 19:02

Rob is correct about separation, strictly speaking (in the UK) they should be 50mm (2") apart. The reason for this is that whilst the electric cable has insulation that will withstand the 120 volts it's designed for, the Co-axial does'nt.
Your suggestion to use a single, shielded, cable with two wires inside for the electric is good, because if it's damaged the fault current will run to earth via the shield (assuming it is grounded) and trip the circuit breaker.
Co-axial, comes in different levels of quality, choose one that's suitable for satellite use and you will get foil+braid as a shield.

As you refer to 120volts, do you live in the US?

stu2007 · 17-03-2008, 19:23

In England the electrical regulations don't allow mains cables (120v same thing) to be run in the same conduit/channel as signal cables unless the signal cables are insulated to the same voltage as the mains.
Easy way round is to pass another smaller plastic pipe/conduit/mini trunking through the pipe and put the coax in that.
As or magnetic problems not sure but a two-core mains cable would be better than single cores.

SMHarman · 17-03-2008, 19:31

Quote:

Originally Posted by stu2007

As or magnetic problems not sure but a two-core mains cable would be better than single cores.

The US does not have Twin and Earth type wiring, you send cable cores to where you need them.

stu2007 · 17-03-2008, 20:17

I was thinking more along the lines of a 2 or 3 core flex. Surely they must have those in the USA.
Alternatively how about twisting the 2 single cores of the lighting circuit together, it would reduce the magnetic effects a lot.

jaym812 · 18-03-2008, 02:43

Quote:

Originally Posted by SMHarman

The US does not have Twin and Earth type wiring, you send cable cores to where you need them.

yes we do it called romex here there14/2 15amps with ground 12/2 20amps with ground and 10/230amp with ground aswell 14/3 12/3 10/3 for 3way lights
we also have 8awg for 40amps and 2/0 for 200amp electric serivces no u cant run low volt wires aka coax,cat5 or 3,anyting under a 120 in the same conduit as a high voltage such as 120 220 240 480 and i know this because i went to electric school and im also a broadband serivce tech for comcast here in the states

handyman · 18-03-2008, 09:22

Quote:

Originally Posted by Draby

Co-axial, comes in different levels of quality, choose one that's suitable for satellite use and you will get foil+braid as a shield.

Don't choose that rubbish, it is not designed for broadband use.

Get some proper 'cable' cable from here. It will be shielded.

SMHarman · 18-03-2008, 13:11

Quote:

Originally Posted by jaym812

yes we do it called romex here there14/2 15amps with ground 12/2 20amps with ground and 10/230amp with ground aswell 14/3 12/3 10/3 for 3way lights
we also have 8awg for 40amps and 2/0 for 200amp electric serivces no u cant run low volt wires aka coax,cat5 or 3,anyting under a 120 in the same conduit as a high voltage such as 120 220 240 480 and i know this because i went to electric school and im also a broadband serivce tech for comcast here in the states

Fair enough, all I have ever seen in domestic buildings is wires not T&E type cables. Not that have looked at much building wiring in the US.
Are there any electrical rules about running power cables and non power cables in the same duct as the Original poster proposed. Certainly there are in the UK and there may be in NJ but not in FL but you are best placed to answer that.

Cybergrizzly · 18-03-2008, 13:35

Ok..Guys, thanks for the responses:

I live in Panama (Central America). There is an Electrical Code for construction down here and technically speaking it says that power cables should be on their own tube.

Regardless of this, it will be a short run underground of about 30 to 40 feet long. Let us say the cable TV cable is a good quality one such as RG-6 with its own shield and instead of sending two #12 wires (insulated), I go with a 3-wire #12 rubber insulated electric cable (leads: positive, negative & ground). An electrical engineer friend of mine says there are "shielded" electrical cables but these are expensive and hard to find and would have to be ordered to USA (closest place to me), but that this shielding would definitely prevent the magnetic field effect against the signal/communication cable).

I would think that the shielding in the RG-6 cable TV coaxial should be enough to protect against the magnetic field created by the electric wires. On the other hand, the single 3-wire electric cable will be rubber insulated and should be most likely well protected against damages (besides, the tube is 1-1/4" diameter which is more than ample and spacious to fit two cables that are about the diameter of any coaxial cable). Would the RG-6 coaxial cable shielding be enough to protect the internet and cable TV signals from the magnetic field created by electric wires?

SMHarman · 18-03-2008, 13:41

Quote:

Originally Posted by Cybergrizzly

Ok..Guys, thanks for the responses:

I live in Panama (Central America). There is an Electrical Code for construction down here and technically speaking it says that power cables should be on their own tube.

Regardless of this, it will be a short run underground of about 30 to 40 feet long. Let us say the cable TV cable is a good quality one such as RG-6 with its own shield and instead of sending two #12 wires (insulated), I go with a 3-wire #12 rubber insulated electric cable (leads: positive, negative & ground). An electrical engineer friend of mine says there are "shielded" electrical cables but these are expensive and hard to find and would have to be ordered to USA (closest place to me), but that this shielding would definitely prevent the magnetic field effect against the signal/communication cable).

I would think that the shielding in the RG-6 cable TV coaxial should be enough to protect against the magnetic field created by the electric wires. On the other hand, the single 3-wire electric cable will be rubber insulated and should be most likely well protected against damages (besides, the tube is 1-1/4" diameter which is more than ample and spacious to fit two cables that are about the diameter of any coaxial cable). Would the RG-6 coaxial cable shielding be enough to protect the internet and cable TV signals from the magnetic field created by electric wires?

So does this tube exist and it is no possible to put another one nearby without digging things up etc?
The reason you want them separated is because if anything happens you don't want the coax now carrying 110v and killing the next person that turns the tv on.
The cost of 40ft of tube is not high. If you can run a second one, then you should and if I were you while you were at it I would run a piece of CAT6 alongside the coax to futureproof this run.
The rules say you cannot for a reason, to prevent people electrocuting themselves on cables that should not be carrying current.
In the UK or the US when the building inspector picked this up they would tell you to disconnect that power circuit until the breach had been fixed. You are trying to convince yourself that this is OK even though the regulations say otherwise.

Cybergrizzly · 18-03-2008, 14:33

SMHarman:

I could not agree more than you. Your response was right to the point. Safety is first and I would not put anyone (be a cable technician or one of my family) in danger if routing the electric wires along with the coaxial presents such a problem.

Suggestion: Since the already installed, buried and under a concrete floor slab PVC pipe is 1-1/4" diameter....what if I route the electrical wiring inside a flexible plastic tube of 3/8" or 1/2" diameter ? The 1-1/4" PVC pipe should be of sufficient diameter to accept the coaxial and the flex plastic tube. Comments?