electric heat pump - failed elec inspection

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Stevenfyeager

Senior Member
Location
United States, Indiana
Occupation
electrical contractor
I re wired a modular home with two 60 amp breakers to a new heat pump furnace. The only thing the inspector said was "confirm breaker size on furnace" I put two 60 amp breakers like the original panel had. He said he never sees a modular home furnace bigger than 15 kw which would be one 60 and one 30. He told me to call the HVAC man, and I will probably need to switch one of the 60 s for a 30. ( he said a 18 kw would be two 60 s) I went back and looked at the furnace, it has two 60 amp breakers on the furnace and the label says 14.5 kw. I called the HVAC man who installed it, he said I did it correctly. But when I call the inspector Monday, I don't know if I am confident I did it correctly. Help. Thanks !
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Locally the installer is required to post the information required by Part IV of Art 424. This information normally includes the MCA & MOCP and the inspectors check to see that the install conforms.
The breakers in the unit itself are most often 60 amp regardless of the OCP required as they serve as a disconnecting means primarily.
.Were I inspecting it I would look for the required nameplate and check that against your conductor size and overcurrent device.
 

Stevenfyeager

Senior Member
Location
United States, Indiana
Occupation
electrical contractor
Locally the installer is required to post the information required by Part IV of Art 424. This information normally includes the MCA & MOCP and the inspectors check to see that the install conforms.
The breakers in the unit itself are most often 60 amp regardless of the OCP required as they serve as a disconnecting means primarily.
.Were I inspecting it I would look for the required nameplate and check that against your conductor size and overcurrent device.
the label on the furnace says : " 240 / 60 /1 " (Volts/ Hz / Phase) and (Element KW / Amps) : 14.5 / 60
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
the label on the furnace says : " 240 / 60 /1 " (Volts/ Hz / Phase) and (Element KW / Amps) : 14.5 / 60

Is that on the furnace or the heater ? Seems odd to me as 60 amps would be the current draw on a 14.5kw heat strip and does not address the blower.
We will see what some of the HVAC guys have to say but here a 14.5kw airhandler/heat would normally have a 50 or 60 amp amp circuit for the 9.6 kw strip and a 30 amp circuit for the other section of heat,.
Ive not seen a nameplate you described on the actual airhandler with blower.
 

Stevenfyeager

Senior Member
Location
United States, Indiana
Occupation
electrical contractor
Is that on the furnace or the heater ? Seems odd to me as 60 amps would be the current draw on a 14.5kw heat strip and does not address the blower.
We will see what some of the HVAC guys have to say but here a 14.5kw airhandler/heat would normally have a 50 or 60 amp amp circuit for the 9.6 kw strip and a 30 amp circuit for the other section of heat,.
Ive not seen a nameplate you described on the actual airhandler with blower.
I tried to copy and paste a photo of the label from my phone, but couldn't get it to paste.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
That's a totally different nameplate than what I normally see and feel like there should be another showing number of circuits, MCA, MOCP, etc but that may just occur in my own small world :)
I can see where there would be some question in that researching Art 424 your would have a 14.5 kw heat load plus the 1/3 HP motor which, with the required 1.25 multipliers, would need a 81 amp feed exceeding the 60 amp max in 424.22 thus requiring some internal OCP or multiple circuits,.

I would go back to the HVAC folks and get documentation of the required supply circuits. Likely the manufacturer has such data.
 

kwired

Electron manager
Location
NE Nebraska
sorry for the small photo, it says Element K.W. / Amps 14.5 / 60
and Volts/ Hz/Phase 240 / 60 / 1
Maximum Motor FLA/ HP 4 / 1/3 Thanks !

You must have a conductor and overcurrent protection that is 125% of that, plus you also need to add the blower, which would give you at least a 80 amp overcurrent device required if it were a single circuit supply.

chances are it has 4.8 kW heating elements and has two on one circuit and one on another. Blower could be on with either circuit and will add a little more to whichever it is on.
 

StarCat

Industrial Engineering Tech
Location
Moab, UT USA
Occupation
Imdustrial Engineering Technician - HVACR Electrical and Mechanical Systems
FCU or Duct Heater Package

FCU or Duct Heater Package

sorry for the small photo, it says Element K.W. / Amps 14.5 / 60
and Volts/ Hz/Phase 240 / 60 / 1
Maximum Motor FLA/ HP 4 / 1/3 Thanks !

That almost looks like an accessory " Duct Heat Package " rather than being integrated into the Fancoil in which case the FAN RLA is going to be shown on the blower nameplate.
Those are implemented in a slightly different manner if that is indeed what you have and they generally must be interlocked for air flow on the control side.
Take note. We are in an age where ALL documentation is going downhill fast. Also unorthodox and extremely cheap "cut corner " methods are common place.
The diversity and unnecessary complexity of HVAC gear is at an all time high with reliability at an all time low.
These are the facts.

Star
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
chances are it has 4.8 kW heating elements and has two on one circuit and one on another. Blower could be on with either circuit and will add a little more to whichever it is on.
Agreed; in every instance I have checked, the blower is on the 10kva circuit, not the 5kva.
 

Stevenfyeager

Senior Member
Location
United States, Indiana
Occupation
electrical contractor
Agreed; in every instance I have checked, the blower is on the 10kva circuit, not the 5kva.
thank you, Since this HVAC told me to tell the inspector that I have wired it correctly and to give his name to the inspector, I guess I am done. But I wonder if this HVAC guy really knows, from some of your comments. I will call another larger company today whom I've known for 30 years to ask them. I need to make sure I did it correctly.
 

kwired

Electron manager
Location
NE Nebraska
thank you, Since this HVAC told me to tell the inspector that I have wired it correctly and to give his name to the inspector, I guess I am done. But I wonder if this HVAC guy really knows, from some of your comments. I will call another larger company today whom I've known for 30 years to ask them. I need to make sure I did it correctly.
I can't read information in your photo, and it only gets blurry if I try to enlarge it. Is that the only information on the unit?

If there is any data plate with maximum overcurrent protection mentioned on it you do need to comply with whatever it says. Am presuming you do have 60 amp conductors, or at least are properly using "next size up rule", if you have 60 amp overcurrent devices.
 

Stevenfyeager

Senior Member
Location
United States, Indiana
Occupation
electrical contractor
Is it information for OP's particular make/model? Is kind of typical but needs to apply to his specific unit.
thank you, I am sorry to say my helper only photographed half the label. I made a trip myself, (it is a long drive so I was hoping to cost less per hr to check this and sent my helper) and saw immediately the two different 60 amp and 30 amp circuits wiring diagram. I am very sorry for your all's time ! It was very evident on the label and again on ANOTHER label inside after I removed the second cover where the terminals are. a 60 and a 30, showing exactly which of the two 60 amp breakers gets which circuit. I showed my helper the photographs. Again, I am sorry for your time! You all have been so helpful to me these few years so I hated to waste your time.
 
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