Roof Top HVAC Units

[maggmick]

Is their a requirement (code) for providing a 120 volt receptacle on or next to a roof top HVAC unit?

 

[kevinware]

Re: Roof Top HVAC Units

Maggmick,
Check out 210.63 "A 125-volt, single-phase 15 or 20 Ampere-rated outlet shall be installed at an accessible location for servicing of heating, air conditioning, and refrigeration equipment. The rec. shall be located on the same level and within 25ft. This rec. shall not be connected to the load side of the equipment disconnecting means.

Don't forget 210.8 for GFCI.

[ July 12, 2005, 02:05 PM: Message edited by: kevinware ]

 

[lady sparks lover]

Re: Roof Top HVAC Units

I believe the code requres gfi or wp/gfi with in 25 feet of a roof top unit. In this office we spec a 120V gfi with the unit, wired on the supply side of the disconnect.

Opps...just saw your response...Kev!

 

[infinity]

Re: Roof Top HVAC Units

I believe the code requres gfi or wp/gfi with in 25 feet of a roof top unit. In this office we spec a 120V gfi with the unit, wired on the supply side of the disconnect

I'm curious as to how you would supply a 120 volt receptacle from say a 2P-40 amp feeder for a roof top unit?

 

[petersonra]

Re: Roof Top HVAC Units

a small xfmr tapped off the line side of the feeder before the disconnect?

 

[infinity]

Re: Roof Top HVAC Units

a small xfmr tapped off the line side of the feeder before the disconnect?

I guess that an xfmr would work. We always just run 2-#12 conductors up to the roof for the receptacle. This seems simpler than getting involved with transformers and overcurrent protection devices.

 

[lady sparks lover]

Re: Roof Top HVAC Units

Originally posted by infinity:

a small xfmr tapped off the line side of the feeder before the disconnect?

I guess that an xfmr would work. We always just run 2-#12 conductors up to the roof for the receptacle. This seems simpler than getting involved with transformers and overcurrent protection devices.

That's true, but are you going to run a 120V line at let's say 100 feet to every unit? The transformer might be much cheaper with wiring cost.

Lady

 

[infinity]

Re: Roof Top HVAC Units

That's true, but are you going to run a 120V line at let's say 100 feet to every unit? The transformer might be much cheaper with wiring cost

Well depending on the placement of the units I would only need a receptacle within 25' so one receptacle may serve several units. A transformer would require a 3R enclosure and overcurrent protection and I would still need to install a receptacle in a box etc. I'd guess that this type of installation would be very subjective. Sometimes the XFMR would be better, sometimes not.

 

[sceepe]

Re: Roof Top HVAC Units

Do you guys think that the hvac receptacle requires a while in use cover as per 406.8. Roof top is a wet location. You doing this lady?

Also, for small units, if you have a 2 pole 15 or 20A feed to the unit why take 2 #12's. Why not just bring a neutral for the outlet (3 wires instead of 2).

Lots of times, on large HVAC units, the mechanical designer can spec a convenience outlet as part of the unit. However, I don't know if the outlet is connected to the line side of the disconnect. I kinda doubt it. (especially on the 480V units)

Lastly check out this link: Click here

A buddy in the office showed me this the other day. Its a disconnect with integral gfi outlet. Says it complies with 210.63 and 210.8. However, it is for "light commercial" which usually means its pretty flimsy and I don't think it complies with while in use requirements of 406.8. I am not sure if you have to bring a neutral to the disconnect or if it has an integral transformer.

 

[petersonra]

Re: Roof Top HVAC Units

I don't think it needs an in use cover. thats appropriate where the outlet is used continuously, but this outlet is just there for the service guy's use a few hours a year.

 

[petersonra]

Re: Roof Top HVAC Units

Something else I noticed. While it requires a 15 or 20 A rated outlet, it does not require that the branch circuit be able to supply 15 or 20A.

Last I looked, there is no requirement that a 15A outlet not have a 5A fuse on it.

Would reduce the xfmr size.

 

[marissa2]

Re: Roof Top HVAC Units

How long do you think that 5 amp fuse would last when the HVAC tech plugs in his vacuum pump.
Lou

 

[lady sparks lover]

Re: Roof Top HVAC Units

Originally posted by sceepe:
Do you guys think that the hvac receptacle requires a while in use cover as per 406.8. Roof top is a wet location. You doing this lady?

I know we spec a weatherproof gfi receptacle, but as far as the "while in use cover", not on our end. We ask the mechanicals to add a GFCI receptacle speced with the unit. This receptacle is completely prewired, so in essence, all we have to do is show up with the 480V, 240V, or 208V. When it is spec with the unit, is a heck of a lot cheaper than running a 120V line to all the units, because it's factory installed. JMO!

Lady

 

[petersonra]

Re: Roof Top HVAC Units

Originally posted by marissa2:
How long do you think that 5 amp fuse would last when the HVAC tech plugs in his vacuum pump.
Lou

did not suggest it was a good idea. just an oversite in the code requirements.

 

[bwyllie]

Re: Roof Top HVAC Units

we have the receptacle installed on its own 120V circuit because if the unit's disconnect is off for repairs the receptacle supplied with the unit is also off.

 

[sceepe]

Re: Roof Top HVAC Units

I don't think it needs an in use cover. thats appropriate where the outlet is used continuously, but this outlet is just there for the service guy's use a few hours a year.

I agree with your logic but 406.8 does not leave any room for logic.

(1) 15- and 20- Ampere Receptacles in a Wet Location
15- and 20-ampere, 125- and 250-volt receptacles installed in a wet location shall have an enclosure that is weatherproof whether or not the attachment plug cap is inserted.

the handboook goes on to say that,

The requirement for this type of cover is not contingent on the anticipated use of the receptacle.

 

[lady sparks lover]

Re: Roof Top HVAC Units

Originally posted by bwyllie:
we have the receptacle installed on its own 120V circuit because if the unit's disconnect is off for repairs the receptacle supplied with the unit is also off.

That's why it's on the line side, with a transformer already factory installed. If the disconnect is off the receptacle fed from the line side remainse on still.

I'm suprised by this.....we always do it this way, of coures it's mainly to save money.

 

[bwyllie]

Re: Roof Top HVAC Units

if it is wired from the line side then you're all set.

 

[sceepe]

Re: Roof Top HVAC Units

The line side of a 480v disconnect will be one wiz bang receptacle. The repair man's drill is gonna work real good for a real short period of time......

edited to add:
since the disconnect is not usually integral to the unit, the outlet and step down transformer cant be upstream of the disconnect.

[ July 13, 2005, 03:56 PM: Message edited by: sceepe ]

 

[raider1]

Re: Roof Top HVAC Units

210.63 Says that " The receptacle outlet shall not be connected to the load side of the equipment disconnecting means".


Chris