Geothermal nameplate

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M. D.

Senior Member
I wired a Climate Master Geothermal heat pump the other day , the name plate called for a min circ. amp of 25.3 , Max fuse/HACR 40 .. The cut sheet marked Electrical Data has a "Supply wire size "of 10 based on 60c. I ran a 10/2 romex and put in a 40 amp breaker. The inspector is questioning the two external circ pumps and whether they are figured into the min circ ampacity.. Again the cut sheet has a column marked "External Pump" FLA 4.0 , each pump is 1.7 amps... and are wired to and controlled by the unit housing the compressor.. I would greatly appreciate any help in formulating an argument.. I really can't afford to eat it . on page 163 you can find the "Electrical Data (TTS)" chart it's a model 038. Oh,.. and 240.4 (g) ? He said he's not sure it applies. HEEEEEELP!!!!!!
http://www.climatemaster.com/share/Res_All_Products_CLM/Section_4_TTS_TTP.pdf
 

kwired

Electron manager
Location
NE Nebraska
If the external pumps are to be powered from the unit (I haven't seen one yet that wasn't that way) then the calculation is is included in the MCA. The nameplate generally states the max current for the external pump, and that is what isused to come up with MCA, as well as max OCP.
 

kwired

Electron manager
Location
NE Nebraska
What is his problem with 240.4(G) it just tells you where to go for specific conductor applications.

If he is not sure about overcurrent protection of the circulating pumps, I can almost assure you the terminals for connecting the external pump probably have about a 7 amp circuit breaker protecting them that comes installed within the Climate Master unit. The branch circuit supplying the heat pump better be obvious it is art 440.
 

M. D.

Senior Member
What is his problem with 240.4(G) it just tells you where to go for specific conductor applications.

If he is not sure about overcurrent protection of the circulating pumps, I can almost assure you the terminals for connecting the external pump probably have about a 7 amp circuit breaker protecting them that comes installed within the Climate Master unit. The branch circuit supplying the heat pump better be obvious it is art 440.
I'm not quite sure what his issue is,. when I spoke to him he was challenged for time.. But I think the gist was that I was going to have to do the calculations for multiple motors ... I told him that I believed that they had included the circ pumps , which all the info points to ,. and that they were protected by and controlled by the unit . and yes the print shows 7amp c.b. .
 

kwired

Electron manager
Location
NE Nebraska
I'm not quite sure what his issue is,. when I spoke to him he was challenged for time.. But I think the gist was that I was going to have to do the calculations for multiple motors ... I told him that I believed that they had included the circ pumps , which all the info points to ,. and that they were protected by and controlled by the unit . and yes the print shows 7amp c.b. .

The manufacturer already did the calculations and the results are on the name plate. Stand up to this inspector, make him prove the results are not on the name plate and don't let him make you prove anything otherwise.

I have been involved with new installs of geothermals in last couple weeks, every one of them had all the needed info on the nameplate. You can double check the math if you want but will likely come up with same MCA as what is on the unit. 440 part IV tells you how. Usually you have 125% of largest motor or compressor plus all other loads, and if you do that, the marked MCA is right on or very close to your result.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
The manufacturer already did the calculations and the results are on the name plate. Stand up to this inspector, make him prove the results are not on the name plate and don't let him make you prove anything otherwise.

I have been involved with new installs of geothermals in last couple weeks, every one of them had all the needed info on the nameplate. You can double check the math if you want but will likely come up with same MCA as what is on the unit. 440 part IV tells you how. Usually you have 125% of largest motor or compressor plus all other loads, and if you do that, the marked MCA is right on or very close to your result.

How do you know that these external pumps are part of the nameplate rating of the equipment? I'm not too familiar with geothermal pumps so is this always the case or is it possible that they have been added to the system and are an addition to the unit??
 

M. D.

Senior Member
O.K. So I sent an email with the "Electrical Data" from the link I posted along with my reasoning . He now accepts that the external pumps are part of the MCA ,. but he wants me to replace the 40 amp breaker with a 30 amp based on a note found in the "Electrical Data" chart which states "current carrying capacity of the wire must not be less than the fuse/circuit breaker size used. Now,.. here in mass we have this revision to 334.80
334.80. Delete the second paragraph and revise the first paragraph to read as follows:
334.80 Ampacity. Type NM, NMC, and NMS cable shall have conductors rated at 90?C
(194?F). Where installed in thermal insulation, the ampacity of conductors shall be that of 60?C
(140?F) conductors. The ampacity of Types NM, NMC, and NMS cable installed in cable tray
shall be determined in accordance with 392.11.












To my way of thinking I'd say the current carrying capacity is 40 amps based on 310.16 for a 90c wire ,.. now there are various code sections that don't allow us to use it at that rating but the wire itself has that current capacity rating nonetheless ... I will change the breaker but I'm not sure I have to..
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
O.K. So I sent an email with the "Electrical Data" from the link I posted along with my reasoning . He now accepts that the external pumps are part of the MCA ,. but he wants me to replace the 40 amp breaker with a 30 amp based on a note found in the "Electrical Data" chart which states "current carrying capacity of the wire must not be less than the fuse/circuit breaker size used. Now,.. here in mass we have this revision to 334.80

To my way of thinking I'd say the current carrying capacity is 40 amps based on 310.16 for a 90c wire ,.. now there are various code sections that don't allow us to use it at that rating but the wire itself has that current capacity rating nonetheless ... I will change the breaker but I'm not sure I have to..

The MCA is 25.3, the #10 is a 30 amp conductor, the OCPD is irrelevant. The inspector is confused. :eek:
 

M. D.

Senior Member
The MCA is 25.3, the #10 is a 30 amp conductor, the OCPD is irrelevant. The inspector is confused. :eek:
What do you mean by irrelevant ? He is saying if I want to use the 40 I'd have to change the wire to #8 he based this on that note in the instructions ,.I'm saying the wire has a rating of 40 and that other factors limit it's use at that rating but the wire itself does indeed have a capacity of 40 amps... what do you think?
 

kwired

Electron manager
Location
NE Nebraska
How do you know that these external pumps are part of the nameplate rating of the equipment? I'm not too familiar with geothermal pumps so is this always the case or is it possible that they have been added to the system and are an addition to the unit??

Nameplate will say something like "Source pump max 4A", right next to where it lists compressor RLA, and blower FLA.

The unit will have terminals for connecting the external pump that usually will have overcurrent protection within the unit, and are connected to the load side of the compressor control contactor. I have worked on two new installs just the past week and some of this info is still fairly fresh in my mind. Plus I have one in my own house.

The pump unit is often actually 2 pumps but they are only 1/20 or even less HP. They are about same thing you see for circulating pumps on smaller boiler heating systems.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
What do you mean by irrelevant ? He is saying if I want to use the 40 I'd have to change the wire to #8 he based this on that note in the instructions ,.I'm saying the wire has a rating of 40 and that other factors limit it's use at that rating but the wire itself does indeed have a capacity of 40 amps... what do you think?

It's irrelevant because you do not use the MaxOCPD size to size the conductor, you use the MCA which you have complied with by using a 30 amp conductor for a 25.3 MCA.
 

M. D.

Senior Member
Nameplate will say something like "Source pump max 4A", right next to where it lists compressor RLA, and blower FLA........
Exactly that. I just went there to change the breaker to a 30.. and that is just what it says on the name plate.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Exactly that. I just went there to change the breaker to a 30.. and that is just what it says on the name plate.

I thought that in the OP you said the max was 40 amps not 30 amps? If so why change the CB?
 

kwired

Electron manager
Location
NE Nebraska
Art 440 basics,

MCA means you need a conductor with an ampacity of 25.3 in this particular install - all calculations are done for you to come up with the marked MCA and they happen to include the source pump if no larger than what is specified on nameplate. You can take MCA and go straight to T310.15(B)(16) to get conductor size. Only time you adjust is if you have more than three current carrying conductors in raceway or a need for adjustment because of ambient temperature.

MOCP is also taken directly from nameplate - all calculations are done for you.

Only time you have to do these calculations is if for some reason the components are not all part of a listed unit, that just doesn't happen much at all with self contained units like found in typical dwellings and light commercial.
 

M. D.

Senior Member
I thought that in the OP you said the max was 40 amps not 30 amps? If so why change the CB?

I did , but then to help prove that the external pump(s) was and or were , figured into the MCA I sent the "Electrical Data (tts) " (see link, page 163 I believe) model 038 which had note (2) to the MOCPD which reads:
current carrying capacity of the wire must not be less than the fuse/circuit breaker size used.
Which the inspectors says means 30 amp breaker per 310.15(b)(16). I'm not willing to spend the fee in mass ,.which I think is $175.00 and a least a day , to fight him on this . The owner had a 2 pole 30 from an old dryer circuit doing nothing so if it helps him sign off I was willing to change it out ,..so I'll get paid. But I'm saying,. in Mass unless the NM is run within thermal insulation the "wire" has a capacity based on the 90c rating which is in fact 40 amps ..
Mass Code:
334.80. Delete the second paragraph and revise the first paragraph to read as follows:
334.80 Ampacity. Type NM, NMC, and NMS cable shall have conductors rated at 90?C
(194?F). Where installed in thermal insulation, the ampacity of conductors shall be that of 60?C
(140?F) conductors. The ampacity of Types NM, NMC, and NMS cable installed in cable tray
shall be determined in accordance with 392.11.
I'll see if I can copy the Electrical Data chart and paste it .
 

kwired

Electron manager
Location
NE Nebraska
I did , but then to help prove that the external pump(s) was and or were , figured into the MCA I sent the "Electrical Data (tts) " (see link, page 163 I believe) model 038 which had note (2) to the MOCPD which reads:
Which the inspectors says means 30 amp breaker per 310.15(b)(16). I'm not willing to spend the fee in mass ,.which I think is $175.00 and a least a day , to fight him on this . The owner had a 2 pole 30 from an old dryer circuit doing nothing so if it helps him sign off I was willing to change it out ,..so I'll get paid. But I'm saying,. in Mass unless the NM is run within thermal insulation the "wire" has a capacity based on the 90c rating which is in fact 40 amps ..

I'll see if I can copy the Electrical Data chart and paste it .

I see what you are getting at with the Note (2) in the instructions, nothing says you have to install max allowed overcurrent device, but most people do to prevent unnecessary tripping at startup (that is when it will happen). So if you want to use max allowed overcurrent device you must use larger conductor. Please note this is not a NEC issue other than 110.3(B) which says to follow instructions provided with the listing.

My next question is even though he is correct, why does the inspector even have the time to catch this - does he read every instruction manual for every piece of equipment you install? If he focuses primarily on NEC he will find nothing wrong with the installing 10AWG on 40 amp breaker.

If he spends that much time on your job he may as well help you while he is there:happyyes:
 
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M. D.

Senior Member
I'm beginning to wonder if anyone what reads what I write.. I sent him an email with a link to the instructions/manuel to help prove that the external pumps were figured into the MCA. But my aguement is that in Mass we have changed 334.80 to this:
334.80. Delete the second paragraph and revise the first paragraph to read as follows:
334.80 Ampacity. Type NM, NMC, and NMS cable shall have conductors rated at 90?C
(194?F). Where installed in thermal insulation, the ampacity of conductors shall be that of 60?C
(140?F) conductors. The ampacity of Types NM, NMC, and NMS cable installed in cable tray
shall be determined in accordance with 392.11.
So in my install there is no thermal insulation and the amb. temp. is not above 86f . but if were and I did need to derate for temp ,.the temp rating I would get to start from is 90c or 40 amps ....so per that stupid note I do in fact have a "WIRE" rated for 40 amps ... What say any and all ????
 
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