120V receptacle without adding additional transformer and panel

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fmtjfw

Senior Member
I don't know of anyone applying that section to a simple unit heater

I read 210.63 as "heating, air-conditioning, and refrigeration". I think it was poorly written to show the real intent. Notice "and" rather than "or". I think the intent is to provide a receptacle for a vacuum pump that can be required for some types of maintenance to HVAC & Refrig. equipment that uses compressible gases in its operation. Simple resistance heaters have no need for vacuum pumps. I think you could request a ruling before you add a transformer and all that that entails.
 

kwired

Electron manager
Location
NE Nebraska
I read 210.63 as "heating, air-conditioning, and refrigeration". I think it was poorly written to show the real intent. Notice "and" rather than "or". I think the intent is to provide a receptacle for a vacuum pump that can be required for some types of maintenance to HVAC & Refrig. equipment that uses compressible gases in its operation. Simple resistance heaters have no need for vacuum pumps. I think you could request a ruling before you add a transformer and all that that entails.

I agree on your analysis of what the intent of 210.63 probably is. But as is worded, any heater would fall under this rule, even a panel heater, pipeline heating cable, immersible tank heaters, or embedded radiant heating cables.

210.64 is new in 2014, but I don't agree it is necessary at all services.

Irrigation equipment being the one I run into - other remote pumping stations however would be similar. If 120 volts is readily available I don't have as much issue with providing a receptacle and probably would have before this was required anyway, but the cost of a transformer to provide a 120 volt receptacle is pointless when the guys that service this kind of equipment almost always have portable generators on their service trucks anyway. JMO.
 

cpinetree

Senior Member
Location
SW Florida
Thanks for the info! I'm aware that you always need a transformer to change voltages. My thought of having one on the unit heater was that it would be one less step I had to take because it would be inside the pre-fabbed unit. All I would have to do is wire the unit heater up and I would meet my requirement for a service receptacle.

Anyway - I looked up the free standing circuit breaker you referenced. Everyone seems to be calling them "Unit Mount C/Bs". I looked for images, but I don't see how they are usually mounted. Is there a common small enclosure that is typically used that would (in this case) sit next to the secondary of the small wall mounted transformer? I'm thinking something similar to a molded case cb.

They mount to DIN rail or with supplied ears (can be bottom mounted or top mounted).
I do not think you will find a pre made enclosure as these are usually oem, with that said I am pretty sure you can adapt a Squared D 2 circuit enclosure to work for you.

See this pdf: http://download.schneider-electric.com/files?p_Reference=0720CT9401&p_EnDocType=Catalog&p_File_Id=1664274475&p_File_Name=0720CT9401R105.pdf
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Thanks for the info! I'm aware that you always need a transformer to change voltages. My thought of having one on the unit heater was that it would be one less step I had to take because it would be inside the pre-fabbed unit. All I would have to do is wire the unit heater up and I would meet my requirement for a service receptacle.

Anyway - I looked up the free standing circuit breaker you referenced. Everyone seems to be calling them "Unit Mount C/Bs". I looked for images, but I don't see how they are usually mounted. Is there a common small enclosure that is typically used that would (in this case) sit next to the secondary of the small wall mounted transformer? I'm thinking something similar to a molded case cb.
So what I would do is buy a vented NEMA 1 enclosure (assuming indoor here) big enough to house a cheap little transformer like a CPT plus one of those little Sq. D QOU breakers, mounted so the handle comes out through a hole (the brackets for them allow that).

1416.jpg
http://www.mouser.com/ds/2/177/1416-746369.pdf

First though, you have to decide on how much power you want to give them. A 500VA CPT will give them about 4A, enough to run a small drill motor but if you want to run a good one like a Milwaukee, it will want 8A, so 1000VA minimum. That will take a larger box. Whatever you decide, you just nipple an outlet box to it and put in a single receptacle (not a duplex) with a nameplate telling the user what the limits are.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
There is a good chance that a vacuum pump for refrigerant recovery will draw more than that. Not relevant to the OP's case, but more general.
 

ramsy

Roger Ruhle dba NoFixNoPay
Location
LA basin, CA
Occupation
Service Electrician 2020 NEC
Just dump 5700 feet of #14 wire into Rubbermaid 50-Gal trash can.
Bring #14 from 1-Pole 15A breaker in 277/480Y panel --thru 5700ft of wire-- to 120v receptacle, then 3ft back to neutral bus.
Sticker above receptacle reads 5-Amp only, anything less blows up whatever's plugged in here.:lol:
 

iwire

Moderator
Staff member
Location
Massachusetts
210.63 requires a 15 or 20 amp receptacle be installed at HVAC equipment

210.21(B)(3) requires those receptacles to be supplied with a minimum 15 or 20 amp branch circuit. (Unless you use a single but then GFCI protection gets a bit tricker)

Therefore in my opinion the minimum size transformer would be 1.8 or 2.4 kva respectively.

We remodeled a large department store and each of the thirteen RTUs had a 0.75 or so transformers for the outlet without proper OCP. During the remodel the roofers smoked almost all of them trying to run large power tools from them.

We got a large extra to run 120 volt circuits to each RTU to fix the situation.
 
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