Whether you are replacing the current wiring of your house or installing a new system that requires you to run a wire from the attic or basement, you will most likely find a hole through which you have a plumbing pipe passing. When a house is being built, construction works drill holes for plumbing lines and electrical wires separately, but it isn’t necessary that your wiring passes perfectly through the holes.
A common question that people ask when this happens is whether it is safe to run plumbing and electrical wire through the same hole or not. Should you invest in metallic or nonmetallic wires for passing through these holes? What does code say about the same?
You can definitely run wires close to plumbing wires, provided you aren’t running a bare or damaged copper wire next to steel pipes. According to the code, you can run plumbing and electrical wires through the same hole, but you need to make sure the wire is well insulated and there is no risk of ruptures. Experts, on the other hand, don’t recommend you do this. Let us consider why.
Running Plumbing & Electrics Through the Same Hole
What NEC Says
One of the first considerations you must make when running wires through the same hole as a plumbing pipe (or even close to plumbing systems) is that you use a 10mm tape around the plumping pipes wherever the two systems touch or come too close to each other.
It is important to consider that if your pipes are metal, we would strongly advise against doing this and that you should consider drilling a new hole a few inches away from the plumbing pipe. PVC pipes on the other hand, won’t be as quick to transmit current but metal pipes will carry current all the way to your fixtures and fittings.
However, PVC pipes aren’t completely safe, either. While there is no direct risk of current from PVC pipes, it is important that you consider the fact that if your wire tends to run hot enough, it might start melting through the pipe and rupture it. This takes a long while and should be identifiable with a little due diligence, though. PVC melts at 185° F (85° C), which is rather achievable for wires. However, if your wire tends to run this hot, you probably used the wrong wire or did something wrong during installation.
The 10mm tape will ensure that even in case of a rupture or damage, the systems don’t connect and become a hazard. It is recommended that you inspect the hole at least once a year (preferably after winters) to ensure everything is safe and secure.
What Experts Say
With proper precautions, running both systems through the same hole isn’t an issue with respect to the code. However, experts say that it isn’t advisable. Experience suggests that Murphy’s Law is a thing and if anything can go wrong, it will.
Copper wires with current running through them need to be separated from water. If you must pass an electrical wire close to your plumbing system, it is recommended that you separate the two systems by at least one inch.
To do this, you will have to drill a new hole next to the plumbing hole. There are no code issues there, provided you are careful with your drill. We will discuss the details of drilling a hole in your wall in a later section.
If construction workers need to run electrical wires and plumbing pipes next to each other, they do so mostly by running a conduit for electrical wires parallel to each other. We mentioned in a previous article that electrical lines and gas lines should be at least 24 inches apart:
Water and electrical lines should ideally be 12 inches apart, while sewage and electrical lines should be at least 24 inches apart. However, these are figures for commercial construction only. Residential construction requirements are relatively more lenient, which means you can only run plumbing and electrics through the same hole for residential projects.
When running the lines, the same recommendations apply here as with running a gas line with plumbing, i.e., the wiring must be well insulated around. This should be done either in a sheath-like Romex and other NM cables or must be in a raceway if the wiring is single such as TW, THW, THHN/THWN, etc.
Furthermore, a copper pipe shouldn’t, under any circumstances, be used for electric wires – even more so if you are running it with plumbing for sewage or fresh water. There is no specific code on not using copper wire for electrical wires but there is a very good reason we are saying that you shouldn’t.
When electric current flows, it generates a magnetic field around itself which ionizes the copper pipes as well. These ionized copper pipes also hold a charge in turn, which effectively means that if you touch it barefoot, you are likely to experience a shock.
Imagine having an inspector over and he touches the wire copper pipe and gets a shock. Wouldn’t that be something?
Depending on where you need to fix the wire, you can simply take a drill bit or a space and drill a few holes in such a manner that they overlap each other. Once that happens, you can easily pass the wire through any surface without facing any issues. By drilling several holes, you are basically making a channel for the wire to pass through. It should take no more than 5 minutes for you to drill and pass the cord.
In a perfect world, you would never have to pass electrics through the same hole. Instead, wires will be fastened around the pipes and a separate hole will be drilled that will be insulated on its own. However, just because the holes are different doesn’t mean there isn’t a chance of a mishap.
When plumbing pipes burst – which is rather common – they spray water all around. If burst in the right spot, it would result in the wire becoming exposed to the water and therefore can result in disaster as well. This means the point of running electrics and plumbing is simply to mitigate damages – not eliminate them completely.
Drilling Walls Effectively for Electrical Wiring
We mentioned above that you should consider drilling a hole right next to the plumbing. However, this sounds much simpler than it actually is. The code allows you to drill much bigger notches in non-load bearing walls than in load bearing walls, which means that before you start drilling with a spade bit, you need to consider whether this is a load bearing wall or not.
To check for a load bearing wall, you should always ask your contractor/landlord if you are unsure. Whilst some people assume that hollow walls are not load-bearing, the top part of the wall might contain wall supports that are load bearing – so be careful before removing a wall completely.
We recommend using a right-angle drill and hole saw bits to ensure the holes are angled correctly. Drill a small hole at first and then start boring it further to increase it in size. We recommend chipping it slowly and steadily to ensure a tight fit for whatever raceway or conduit you are using. If the hole is angled, you will have a difficult time pulling the cable through it since it would get stuck on sharp edges again and again.
Try to keep the holes centered on the studs. You can use a spirit level to get a level hole and a consistent height, but beginners should avoid having to do this since it can lead to a disbalanced drill and damaged walls.