homeowner who was duped by contractor

Status
Not open for further replies.

nagle47

New member
Location
NE PA.
Hi,, Can someone help me by answering this question. What size wire and what size Circuit breaker is needed to hook up a 5kw heat strip in a Nordyne/Miller heat pump.Q5rd. ??
My 4 1/2 year old compressor went bad and when the HVAC contractor came to diagnose the problem,, he told me that the wiring for the separate 10kw and 5kw heat strips were wired incorrectly even though I never had problem with the heat strips before. He changed the wiring and CB on the 5kw from 10/2--30amp to 6/2 -- 60amp. I am currently getting heat by keeping the thermostat on Emergency Heat until the warrantied compressor arrives. But Recently,, I was told by the master electrician who initially hooked up the 5kw, that the current wiring is oversized,, a possible violation of the NEC code and possibly a potential fire hazard. Is this new wiring a fire hazard and should I change it back to 10-2---30amp CB ?
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
I am going to reopen this thread, at least temporarily. It appears to me that this is not a DIY situation. The OP did not do the wiring change himself, and is not proposing to change it back himself. Rather, he is asking for our opinions regarding the information he was given by an HVAC contractor and by a master electrician. So long as we stay away from giving advice on how to do any installation work, and only talk about the conflicting information he was given, I believe this thread will comply with forum rules.

My answer is that the change to upsize the wiring and breaker for the 5kw heat strip may, or may not, have been necessary. What you did not tell us is whether the heat strip was supplied at 120 volts or at 240 volts. You can tell which is which by looking at the circuit breaker serving this load. Does it have one handle, and is it the same size as most of the other breakers in the panel? That would be a 120 volt source. Or does it have two handles, and it is twice the width of the other breakers? That would be a 240 volt source. I suspect it is the two-handle version. In that case, the original #10 wire and 30 amp breaker was OK, and the change was not needed.

As to changing it back, I don't think that would be necessary either. But I want to ask my fellow forum members for their opinions. A 60 amp breaker and a #6 wire are properly matched to each other. There are components that tell us the maximum breaker size that we can use to serve the load. But I doubt that a strip heater would fall into this category. In that case, I see neither a code violation nor a risk of fire in leaving the #6 wire and the 60 amp breaker in place.

Back to the OP: What is the situation for the 10kw heat strip? Did the HVAC contractor suggest upsizing that one as well?
 

dkidd

Senior Member
Location
here
Occupation
PE
The should be information somewhere on the Minimum Circuit Ampacity and Maximum Overcurrent Protection.
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
#6 and 60 amp breaker is generally correct. However you state there is a seperate 10kw and a 5kw
Strip heat apparently not powered from the condensing unit. If so that is :
10kw+5kw = 15kw/ 240v = 62 amps @ 240. That still would be a undersized circuit as it is over.

If only the 5 kw strip is on this circuit then 5kv / 240 = 20.8 amps. well within the limits.
I don's see how both strips were powered by the original 30 amp circuit. The breaker would never hold if the both were running.

So you need to know how each strip was powered.
 

Fulthrotl

~Autocorrect is My Worst Enema.~
The 60A breaker would not be appropriate if the install instructions for the strip specify a smaller breaker. Otherwise it's OK.

a quick google search brought this up:

MOP = [2.25 x (Rated Current of Largest Motor)] + (Other Motor Loads) + (All Heater Loads)

in any event, #6 wire is sufficient, and it's a relatively inexpensive fix to put a smaller breaker
on it, and even easier to change fuses on the fused disconnect to the correct size... changing
fuses doesn't normally require a sparky.

based on the model number provided, we can't really determine what the MOP should be.... :huh:

http://www.nortekhvac.com/literature/975c.pdf
 

mgookin

Senior Member
Location
Fort Myers, FL
Hi,, Can someone help me by answering this question. What size wire and what size Circuit breaker is needed to hook up a 5kw heat strip in a Nordyne/Miller heat pump.Q5rd. ??

My 4 1/2 year old compressor went bad and when the HVAC contractor came to diagnose the problem,, he told me that the wiring for the separate 10kw and 5kw heat strips were wired incorrectly even though I never had problem with the heat strips before. He changed the wiring and CB on the 5kw from 10/2--30amp to 6/2 -- 60amp.

I am currently getting heat by keeping the thermostat on Emergency Heat until the warrantied compressor arrives.

But Recently,, I was told by the master electrician who initially hooked up the 5kw, that the current wiring is oversized,, a possible violation of the NEC code and possibly a potential fire hazard. Is this new wiring a fire hazard and should I change it back to 10-2---30amp CB ?


I can't speak for PA but in FL that HVAC contractor would have been working outside the scope of his license. To say it bluntly, it's called unlicensed contracting.

I think you misunderstood the electrician. Wiring can not be oversized. It can only be undersized. All references to wire sizes are minimums. There are no maximums (for your purpose). If that wiring is otherwise properly installed, it need not be changed out due to its size alone.
Now if the manufacturer's instructions say the maximum overcurrent protection for the heater circuit is something less than 60A, then yes, that would be a violation as others have stated.

Do you have separate circuits for the 5kW and the 10kW heaters? If so, what size breaker is the 10kW heater on?
Do you have 2 split systems in your house or 1?
 

Ingenieur

Senior Member
Location
Earth
Most ahu's associated with a heat pump have 2 circuits
Mine
stg 1 htg in case 5 kw plus fan mine is 4 A min ckt amp/max cb 30/30
stg 2 htg in my case 10 kw min ckt/max cb 60/60

the ckt was fine at 30/2 #10

I wonder if it was stg 2 that was rewired?
 

growler

Senior Member
Location
Atlanta,GA
But Recently,, I was told by the master electrician who initially hooked up the 5kw, that the current wiring is oversized,, a possible violation of the NEC code and possibly a potential fire hazard. Is this new wiring a fire hazard and should I change it back to 10-2---30amp CB ?

I think it's safe to say that this is not a fire hazard. It may be a code violation.

Useing the wrong breaker may affact the warranty of the product but it was installed by the HVAC contractor and would be his fault. Keep any paperwork showing that the circuit was installed by the HVAC contractor.

The HVAC contractor is supposed to be the one that knows the correct size breaker for this unit.

If you are thinking that you were duped by the HVAC contractor into paying for a circuit that you didn't need then I guess a lawyer is your best bet.
 

Ingenieur

Senior Member
Location
Earth
op
go to the inside ahu unit (not the outside one)
no tools are required
just a phone w/camera and a flashlight

look for a label on it 4"x6" or so
will have ratings etc on it
take a picture

on the unit will be 2 circuit breakers, side by side, sometimes under a clear flip up cover
take a picture

post both pics
 

JFletcher

Senior Member
Location
Williamsburg, VA
Not enough info for a totally accurate answer I'm afraid... there are several models that start with Q5RD. Some newer models of heat pumps/packs with electric emergency heat require 2 circuits: a 240V 30A with #10 wire (would generally be orange colored Romex or non-metallic cable), an a 240V 60A with #6 (which will be a large black colored cable). There would be 2 disconnects and 2 2 pole breakers in your panel per unit. The few I have worked on are internally fused.

You can check to see if you have a model like this by looking at the wiring diagram, except that what I saw said these are not shipped with the aux/emergency heat strips; it is a separate kit. Since you are not an electrician I cannot advise opening the unit to check the wiring.

Bottom line: the wire cannot be too big. A 10kw heater would draw 41.7A. As its a continuous load, the circuit must be sized 125% of that, or 52.1A, which is too much for a 50A breaker, thus the next standard size of 60A would be used. If the breaker is somehow too big, it can be switched out for a smaller one relatively easily and inexpensively.

Normally I'd take the word of an electrician over an HVAC guy, however that the electrician told you the wiring is too big, and my calculations coincide with what the HVAC man installed, I believe the HVAC guy.

eta: the unit may have never had problems with the electric heat as it generally does not run; the unit runs on heat pump mode. Electric heat is for heat pump failure or if the differential between house temperature and thermostat setpoints is too great.
 

JFletcher

Senior Member
Location
Williamsburg, VA
op
go to the inside ahu unit (not the outside one)
no tools are required
just a phone w/camera and a flashlight

look for a label on it 4"x6" or so
will have ratings etc on it
take a picture

on the unit will be 2 circuit breakers, side by side, sometimes under a clear flip up cover
take a picture

post both pics

I totally missed your posts. Good idea. Also, nagle47, check to see if there is a flat-ish/oval orange cable (#10 NM) and a larger (penny-nickel sized) black cable (#6 NM) going into your unit, and a 30 and 60A breaker in your panel marked 'heat pump' and 'electric heat' or something similar. See if you have one or two disconnects (usually a grey box roughly 5" wide by 10" high) at the unit. Pictures will absolutely help.

nagle47, although I cannot speculate on if you have a fire hazard or not, what I will say, with the information you have provided, is that if it were my house, I'd sleep comfortably tonight. I do not think you have been duped, tho as mgookin mentioned, an electrician should have run this wiring, and an electrician should double check it. Maybe one did = many HVAC companies here are also licensed in electrical work.
 

kwired

Electron manager
Location
NE Nebraska
These type of units can be ordered with different options, around here they almost always come with internal breakers. I believe listing requirements limit their design to 60 amp circuits so every ~10 kW section or lesser will be on it's own breaker. Some may have a common bus so you can feed the entire unit with a single larger circuit though, usually it is removable so you have option of single or multiple circuits feeding the unit.

5 kW circuit would need at least a 30 amp circuit supplying it. More common is an actual rating of 4.8kW which could be on a 25 amp circuit. Some factory installed breakers will actually be 25 amps, others 30 amps, and I have seen 4.8 kW units with factory installed 60 amp breakers also.

Reality is same 4.8 kW element is used on 50 or 60 amp circuits rated for 9.6 kW, there just happens to be two elements in those instances, so I have little concern for it being protected at 60 amps as long as the field installed conductors are 60 amp conductors, though there are technicalities of what is proper here.

(50 amps is usually the proper rating for a 9.6 kW circuit without a blower on the circuit, 60 amps is usually proper if there is a blower on the circuit)

The contractor in the OP possibly seen a 60 amp breaker in the unit (some seem to put in 60's regardless of what elements are used), and figured it needed a 60 amp supply circuit. As someone else mentioned - look at the name plate and use what it calls for. If it is only a 5kW unit it should call for a 30 amp circuit max unless the blower is on same circuit and puts you over that - but that would be a huge blower for a relatively small heater unit.
 
Ive never heard of a fire hazard by oversizing the wire if anything it its the opposite, you might be being duped by the master electrician. If the unit was inspected and passed I'd assume it is correctly sized. If he was referring to the wiring on the inside of the unit air handler/package whatever its installed by the manufacturer not the installing contractor, and its sized right. If your talking about the feeder it should be #6. If he changed the feeder to the unit to #10 lots of laughs call an electrician to change it back and a lawyer to sue the electrician that made changes.
 
Hi,, Can someone help me by answering this question. What size wire and what size Circuit breaker is needed to hook up a 5kw heat strip in a Nordyne/Miller heat pump.Q5rd. ??
My 4 1/2 year old compressor went bad and when the HVAC contractor came to diagnose the problem,, he told me that the wiring for the separate 10kw and 5kw heat strips were wired incorrectly even though I never had problem with the heat strips before. He changed the wiring and CB on the 5kw from 10/2--30amp to 6/2 -- 60amp. I am currently getting heat by keeping the thermostat on Emergency Heat until the warrantied compressor arrives. But Recently,, I was told by the master electrician who initially hooked up the 5kw, that the current wiring is oversized,, a possible violation of the NEC code and possibly a potential fire hazard. Is this new wiring a fire hazard and should I change it back to 10-2---30amp CB ?


Further the 5 kw and 10 kw are controlled internally by controls within the hvac there is one feeder coming in to both heat kits the wiring internally is sized for each kit. The main feeder would have never passed with #10 wiring as a feeder you need to get clarification of the work done
 

junkhound

Senior Member
Location
Renton, WA
Occupation
EE, power electronics specialty
re: told by the master electrician who initially hooked up the 5kw, that the current wiring is oversized, a possible violation of the NEC code and possibly a potential fire hazard

Going by just that statement, if that is what the electrician actually said, the electrician is a hack and a charlatan and license should be revoked.

As others have said, no such thing as 'oversized' except in economic aspects of installation.
 

kwired

Electron manager
Location
NE Nebraska
re: told by the master electrician who initially hooked up the 5kw, that the current wiring is oversized, a possible violation of the NEC code and possibly a potential fire hazard

Going by just that statement, if that is what the electrician actually said, the electrician is a hack and a charlatan and license should be revoked.

As others have said, no such thing as 'oversized' except in economic aspects of installation.
And maybe trying to land a 500 kcmil conductor on a device intended for 6 AWG max:)
 

growler

Senior Member
Location
Atlanta,GA
re: told by the master electrician who initially hooked up the 5kw, that the current wiring is oversized, a possible violation of the NEC code and possibly a potential fire hazard

Going by just that statement, if that is what the electrician actually said, the electrician is a hack and a charlatan and license should be revoked.

As others have said, no such thing as 'oversized' except in economic aspects of installation.

Technically there is no such thing as an oversized conductor but if I'm the one paying for it I would think of this as oversized (larger than required or needed).

Either the electrician or the HVAC contractor is wrong here but I wouldn't give better than even money on either one.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
I would not be so quick to start throwing out insults to a licensed EC we don't know, who was THERE, based on incomplete info from the homeowner and an HVAC technician. For all we know the EC told him the CIRCUIT was over sized, but the OP heard or interpreted that as "wiring", when in reality the EC was referring to the entire circuit, including the OCPDs involved. We just can't tell from here.
 
Status
Not open for further replies.
Top