310.4 Electrical Connections and AC Disconnects

Installing According to Code is the Sign of a Real Professional

So many times when you’re out in the field you’ll encounter a technician, a supervisor or inspector who will cite building codes as their authority for proper installation of an HVAC system.  Installing a subpanel, wiring up a disconnect, or running PVC pipe in the attic correctly is just one of the many responsibilities of an HVAC technician.

Whether you pull permits or not on your job, a company’s worth is based on the quality of its workmanship.  And if that work fails in a few years, it most likely wasn’t installed according to code.

So often you will notice the code referring us back to the manufacturer and how they want it installed.  Referring to the installation guide and following along with the steps in the book will take any and all guesswork out of what you’re supposed to do next.  This is the sign of a real professional in their trade.
I’m not here to claim I know, or could even possibly interpret all the codes correctly, but what I would like to do is open up some conversation about the building codes and your opinion about what we are talking about this particular day.

Electrical Connections at the Condenser

Today I want to talk about installing a service disconnect at the condenser.  I will look at one of the first points made in the California Mechanical Code and it stands out from the International Mechanical Code which just advises following the NEC when it comes to this.  But as an installer, I’ve wondered whether or not to put a disconnect here.  Let’s take a look at what 310.4 says about Electrical Connections.

First, “equipment regulated by this code requiring electrical connections of more than 50 volts shall have a positive means of disconnect adjacent to and in sight from the equipment served.”  This just means a furnace would need a 120-volt pigtail as its positive means of disconnecting voltage from the furnace.  When you unplug the furnace, no voltage can reach the furnace.  A 30-amp or 60-amp service disconnect is installed on the 240-volt circuit to the AC outside as its positive means of disconnect.

Here’s a question for you.  Let’s say we’re installing the AC unit.  Usually, the disconnect is right next to the condenser so the service tech can access the unit safely.  Must we always have a disconnect next to the AC to remove power from the unit?  The answer is no.  If the main electrical panel is within sight of the condenser, that can serve as the means of positive disconnect for the unit.  The double pole breaker inside the main electrical panel is that means of disconnect.  This has come up a few times for us when teaching new technicians.

Dedicated Outlets

Next, “a 120 Volt receptacle should be located within 25 feet of the equipment for service and maintenance purposes.  The receptacle need not be located on the same level as the equipment.” 

So, because we service our equipment with pumps and motors that require electricity, an outlet needs to be within reach of a 25 ft. extension cord.
As specified later in the codebook, in the case of a package unit installed on a roof, a dedicated outlet at the unit must be installed in certain jurisdictions.  Here in Yolo County, right next to Sacramento County, we must install 120 weatherproof outlets at the package unit on the roof we’re servicing in order to meet that city’s more stringent adaption of the code.  This allows us to use our vacuum pumps and recovery machines up on the roof.

Exposed Thermostat Wiring

The third part of this code requires that “low voltage wiring of 50 volts or less… shall be installed in a manner to prevent physical damage.”   This is kind of a pet peeve of mine.  It bothers me to see thermostat wire running to the AC with its brown sheathing exposed to the sun’s UV rays.  Even the slightest bump of a dried out thermostat wire against the AC is enough to strip the wire and expose it to an electrical short.  One-half-inch conduit should be run with the thermostat wire to protect it from damage.  It really doesn’t take any extra time to install this flexible non-metal conduit right into the condenser.  Some techs just don’t think about it, because they weren’t taught that way.  It’s all good.  Once again, just starting a conversation about this.

Your Turn

What are your thoughts about this section of the code that talks about electrical connections?  Do you always put a disconnect next to the AC even though it’s in sight of the main electrical panel?  Please leave your thoughts below.

Thanks for weighing in, and stay tuned for next week’s blog topic!

Don’t miss our YouTube video on this topic:

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