VAV's

[Alwayslearningelec]

I always see VAV's on blueprints with a toggle disconnect switch. Is that code to have means of disconnect at the VAV? THanks.

 

[Tulsa Electrician]

Got a pic.of symbol. And the legend. Many different applications. I would say yes means of disconnect. Some are thermal protected motors and some are not. So the type will vary per application.

 

[infinity]

The ones on our current project use 24 volt motors with an integral 277-24 volt transformer. We use a single pole toggle switch.

 

[steve66]

Assuming we are talking about a box that only has dampers, and not a fan powered VAV.

I usually see them with with 120 volts to a transformer for each VAV, or more often, one transformer that supplies several VAV's.

The motors are small enough that I don't believe any disconnect is required for each VAV, although one might be required for the transformer.

 

[petersonra]

The motors are small enough that I don't believe any disconnect is required for each VAV, although one might be required for the transformer.

It is still required but there is some dispensation to use the branch circuit OCPD as the motor disconnect for small motors.

 

[DooWop]

The ones I've installed are either 110v or 230 v. The information with the indoor units shows a 3 pole switch to fully disconnect the unit.
Most all equipment provides a disconnect means even if it's only a pig tail.

 

[tom baker]

Every motor requires a disconnect, including bath exhaust fans, electric clocks…disconnect typically must be within sight of motor, please review 430.102

 

[steve66]

Every motor requires a disconnect, including bath exhaust fans, electric clocks…disconnect typically must be within sight of motor, please review 430.102

So how does that fit in with 430.109 B, which says that for stationary motors of 1/8 HP or less, the branch circuit OCP is permitted to serve as the disconnecting means?

I'm never sure if 430.109 B applies to the disconnect at the motor, or to the one at the controller, or to both required disconnects.

And 422.31 (A) says that the branch circuit OCP may be permitted to serve as the disconnecting means for an appliance.

I take those two paragraphs to mean we can forgo the disconnect at each VAV, and just use the branch circuit OCP for a disconnect to multiple VAV's.

 

[petersonra]

So how does that fit in with 430.109 B, which says that for stationary motors of 1/8 HP or less, the branch circuit OCP is permitted to serve as the disconnecting means?

I'm never sure if 430.109 B applies to the disconnect at the motor, or to the one at the controller, or to both required disconnects.

And 422.31 (A) says that the branch circuit OCP may be permitted to serve as the disconnecting means for an appliance.

I take those two paragraphs to mean we can forgo the disconnect at each VAV, and just use the branch circuit OCP for a disconnect to multiple VAV's.

You can often use the controller disconnect as the motor disconnect, and sometimes you can use the branch circuit OCPD as the motor disconnect. But, you still have to have a motor disconnect.

Since a light switch will suffice as a disconnect for a small motor like this, it seems to me to be a good idea to put one by the small motor so you don't have to figure out where a motor disconnect might be hidden.

 

[tom baker]

That’s why I said typically. And for a VAV, if you set a j box to transition from emt to flex, put a snap switch there.

 

[steve66]

You can often use the controller disconnect as the motor disconnect, and sometimes you can use the branch circuit OCPD as the motor disconnect. But, you still have to have a motor disconnect.