advice needed....

G

g-and-h_electric

Senior Member
Location
northern illinois
Occupation
supervising electrician
I need a bit of advice.

Had to go and wire up a replacement of an electric furnace. The original unit was connected to a 2p 60 Amp breaker, with a 60 Amp no fuse disconnect adjacent to it ( when I arrived all that was there from the old install was the disconnect and whip, no further info on the old unit).

The new unit is a 15kW Trane unit with the heating element divided up into to 2 circuits one at 60 Amp for 2 sets of elements ( including the control circuit and blower), the other at 30 Amp for the 3rd set of elements.

My problem is this: The service panel (located in a closet on the other side of the wall from the furnace) is bolt on GE panel. The ONLY 2 "stabs" left in the panel both have the bolt holes stripped! My options are these: 1 ) locate a GE 2p80 bolt on, use #4 conductors to the furnace, and "polaris tap" them in the furnace junction box to feed each of the 2 OEM breakers. 2) find a new GE interior for the panel. 3) find (if they exist) 2 GE bolt on duplex breakers to give me the space to use a standard 2 pole breaker for the second furnace furnace circuit.

Is there any reason why option #1 cannot be used? The "tap" conductors can be #6, and less then 3 feet long). Do the breakers I mentioned in option 3 exist? I know siemens makes this type of breaker, and I think eaton does too for the bab series panels. Due to the potential lead time, cost and possible lack of availability, I am thinking option #2 is not really practical unless it is my only option.

Any thoughts or ideas??? This is a condominium, and the closet is tight for space, as is the mechanical closet


Howard
 
Yes, I could do a 4 ckt sub by the furnace ( there is room), I was trying to avoid that as the furnace has 2 front accessible circuit breakers providing OCP, and local disconnection.

I was trying to keep thing simple and less expensive, BUT be code compliant.

Howard
 
Siemens 4 circuit panel nema 1 is like 30 bucks. Maybe 200 in wire and 100 for the bigger bolt on. Anything else you're spending a dollar to save a nickel. If you're charging T and M for this since it's a change order do to having damaged equipment and different site conditions don't sweat it. If it's the boss breathing down your neck tell him who's gonna be responsible for fixing this when it doesn't pass inspection. Then do it.
 
CoolWill said:
Or identify circuits in the panel that are lightly loaded and double up to make room for another breaker.
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still need to run additional cable to the unit location though it only would need to be a 10 AWG cable vs #4 if you went with a single circuit. So may come down to how long and easy to install is the run being a factor as well. Might make different decision when confronted with same change of units but yet different installation conditions.
 
Little Bill said:
Better check to see if those breakers are actually for OCP. Most air handlers that I have wired say something like "The breakers are for disconnect only, not OCP".
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Yet most will vary the size they put in based on what it is supplying. If it were only for disconnecting means why wouldn't they just install 60 amp for every situation or even just go with molded case switches with no overcurrent protection? They could purchase just one stock item and at higher quantities for possibly better pricing if they did that. The penny pinchers would go for it even if they didn't pass that savings on when selling their items.
 
Thank you all for the advice and insights.

Never thought about the "breakers" on the unit as not having OCP. As it was the ONLY breaker I could find in the Chicago area was a 100, therefore sub panel it was. There is now a 4 circuit sub, adjacent to the furnace with a 2p60, and a 2p30, all is good.


Howard
 
Little Bill said:
Better check to see if those breakers are actually for OCP. Most air handlers that I have wired say something like "The breakers are for disconnect only, not OCP".
Click to expand...

Maybe the thing is more of a case of if the unit is listed for single supply circuit. Some specifically have ratings on nameplate for single as well as multiple supply circuits. Many that have single supply information also have an optional lug kit that can be installed to accommodate the single supply circuit.
 
Why are you "trying to do it as cheap as possible"? Someone before you screwed it all up by stripping the buss out, why not try and sell them a new panel and add some future spaces? Unless you are a charity and not in the business of making money.
 
acrwc10 said:
Why are you "trying to do it as cheap as possible"? Someone before you screwed it all up by stripping the buss out, why not try and sell them a new panel and add some future spaces? Unless you are a charity and not in the business of making money.
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Not all companies want to just blow money.
If your a small business or just like to keep money, sometimes the cheapest way that can last another 10-15 years works better than new…,
Balance act… I try and upsell but sometimes people don’t want that. As long as it’s code complianct who cares

Your way is better for your business though
 
Unfortunately, changing the panel is not a really viable option for several reasons. First,the unit is a condo with the feeders going to "lord knows where" in the basement. Second, it is flush mounted in the wall of a closet ( call it the electric room). Third, it is a 3 phase "commercial" panel ( removing the tub would be a mess).

This was a bid job by our HVAC division, and agreed the problem found was a "hidden condition" we try to not be the guys that quote one thing and build another.

I will have our estimator look into the "combining kit". If TRANE makes them for these units, then all I will need in the future is a bigger breaker.

This isnt the first time I have worked in a condo building in the area with 15+KW of heat on a 60..... How this ever worked for as long as it did is beyond me!


Howard
 
Ok, so the job I asked about is long done, and all is well.

I have 1 other question with regard to the described situation. IF I had no room to either add a subpanel due to the physical constraints of BOTH the mechanical and electrical closets, the following thought APPEARS to be code compliant....... 60 Amp breaker feeds the first 2 elements of the electric furnace, and the circuit for the 3rd unit (generally 30 Amp) is then shared with the air conditioning condenser circuit? Obviously there would be a pigtail from the breaker to both of the loads served.

My interpretation is that this is compliant, as the loads are interlocked to prevent simultaneous operation and non coincident.

Am I reading the code right?

Just trying to find answers for the future installs.


Howard
 
g-and-h_electric said:
Ok, so the job I asked about is long done, and all is well.

I have 1 other question with regard to the described situation. IF I had no room to either add a subpanel due to the physical constraints of BOTH the mechanical and electrical closets, the following thought APPEARS to be code compliant....... 60 Amp breaker feeds the first 2 elements of the electric furnace, and the circuit for the 3rd unit (generally 30 Amp) is then shared with the air conditioning condenser circuit? Obviously there would be a pigtail from the breaker to both of the loads served.

My interpretation is that this is compliant, as the loads are interlocked to prevent simultaneous operation and non coincident.

Am I reading the code right?

Just trying to find answers for the future installs.


Howard
Click to expand...
I’d argue in your favor
 
g-and-h_electric said:
and the circuit for the 3rd unit (generally 30 Amp) is then shared with the air conditioning condenser circuit? Obviously there would be a pigtail from the breaker to both of the loads served.

My interpretation is that this is compliant, as the loads are interlocked to prevent simultaneous operation and non coincident.

Am I reading the code right?

Just trying to find answers for the future installs.


Howard
Click to expand...
If its really just a 'air conditioning' condenser I think so, however I'd bet a milkshake on most newer units or change outs that 'air conditioning' condenser really becomes a heat pump, it would be kinda nuts in 2025 to just have electric resistance heat and in that case I'd say no, unless possibly you could tie it to the 2nd heating stage. but thats probably the 60A breaker.
 
Thank you all for the info! :) The units are mostly air handlers with electric heat strips and not heat pumps. These units are in 1970's vintage condo buildings that are all electric (water heater, range etc) and are usually just "like for like" swap outs. If we happen to sell a heat pump system, then I will have to either add a breaker for eh 3rd heat strip, or a sub panel like I just did.

Chicago isnt a real great market for heat pumps, due to the winters having more than a few days of below 30F temperatures. Also, if a heat pump were to go in our HVAC guys would have to either repull the control wiring or use the "add a wire" kit, and all the condensers are on the roof (I dont want to see what is going on up there!! )


Howard
 
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