It can prompt some concerns to find out that wires are touching your dryer’s ducting. Or, perhaps, you are trying to find the best system for your ductwork, and it happens to be near some house wiring.
The obvious concern here is that dryer ducts get hot, and heat is bad for electrical wiring. But actually, the risk isn’t that great, a fact that is supported by the building codes.
Romex cables can touch a dryer vent due to the temperature rating that the insulating materials provide. Ductwork likely gets to a maximum of approximately 130 ℉, while the insulation can handle 194 ℉. Romex cables should withstand contact with the ducts of a well-maintained dryer and exhaust system.
IRC Conditions for Wiring and Dryer Vent Contact
Section M1502 of the International Residential Code (IRC) contains the regulations for venting clothes dryers, including the duct dimensions and appropriate termination. However, there is no mention of preventing contact between electrical wires and ducts and vents.
The IRC covers electrical wiring methods in Chapter 38 but this chapter also doesn’t mention keeping wires away from vents.
The building codes cannot mention every situation or circumstance. However, they do contain the most pertinent ones, particularly those that have to do with health and safety.
So, when I say that the code supports the idea that electrical wiring, like Romex, coming into contact with dryer ducts is not that great a risk, I mean that they see no need to protect against such a setup explicitly.
One factor to consider is what the manufacturer says. According to Section M1502.1, dryers must be vented as per manufacturer instructions.
Manufacturers are considered experts on installing and using their products safely and correctly, so if the dryer has a relevant safety rating, the IRC views the directions as acceptable.
So, if the manufacturer of your dryer says to avoid contact between electrical wiring and the dryer ducts, then you need to follow this to be code-compliant.
Another factor to note is that Section E3802.2 does say that the wires must be protected from physical damage.
Such damage might reasonably occur if any part of the duct was compressing the wiring or was too hot for the wire insulation to withstand.
Compressed cable sheathing results in damage that can make the wires dangerous by exposing the conductor inside. The same can result if the protective covering around the wires melts or disintegrates.
Now, touching and compressing are not the same thing, so if you are concerned about Romex and dryer ducts touching, you are worried about melting or disintegrating the protective sheath. However, these are designed to withstand high temperatures.
Determining if Romex Can Touch Dryer Vent
So, whether or not Romex and dryer ducts can come into contact depends on how hot the ducts get and how much heat Romex wires can withstand, which depends on what insulation they have.
Just to be sure, remember that compressive contact is not permitted.
How Hot Do Dryer Vents Get?
To reach a conclusion, we need to know how hot dryer vents can get. Gas dryers tend to have higher maximum temperatures than electric dryers, and they also heat faster.
Typically, dryer air is heated to 120-160 ℉. Since this is the temperature in the drum, you can expect the ducts to be a slightly lower temperature. As a result, the ducting is commonly found to reach around 110-130 ℉.
Dryer ducts are made of either galvanized steel or aluminum. Galvanized steel is pretty heat resistant but will get hot.
Generally, wire insulation should be fine up to around 194 ℉, depending on the materials used. The copper inside the insulation shouldn’t be affected by the heat, but the insulation is there to prevent failures, fires, and electrocution.
Dryers have safety sensors that make the appliance cut out over 180 ℉ as this is considered overheating and is a fire hazard, so your ducting shouldn’t reach a temperature that can damage the insulation if the wires touch the duct.
There can, however, be situations where dryers overheat and the safety measures fail, so it’s always best to take care of your dryer and ducting.
What Are Romex Wires Insulated With?
Romex is a brand of non-metallic sheathed electrical cable (NMC/NM). The covering on NMC and NM cables is designed to be flame-resistant and moisture-resistant.
Romex sheathing is typically made from PVC (polyvinyl chloride) thermoplastic (plastic with a high temperature rating). The materials of the sheathing mean that Romex cables are rated for temperatures up to 194 ℉.
Romex cables mustn’t be exposed to heat above this rating. This is because thermoplastics soften and distort when exposed to excessive heat and pressure (hence why compression is not good). When this happens, the covering can break and warp, exposing the metal inside.
The PVC aspect is what makes the cables moisture-resistant. The fact that Romex cables are rated for installment in damp locations is an added benefit since any breaks in dryer ducting can result in condensation leaking out of the exhaust system.
Due to the temperature rating for Romex insulation and the expected maximum temperatures that a dryer and its ducts can reach, it should be safe to have the wires touch the ducting.
It is just important to keep up with maintenance and cleaning for the dryer and ducting to prevent overheating issues.