any of you genius in Electrical help me ;) ? breaker sizing etc

[acguytx]

IM HVac i know the correct way to do this but looking for alternatives. Have customer who was running 15KW ph 1 resi heat strips, so we replaced it with the same 3 ton air handler..

however the heat kit came with two service disconnect breakers which is normal but she only has a 60AMP 240V main and even though this is a X13 and uses less electricity then her old one it still draws 66amps when running all strips and blower.. i know it most likely could handle this in short run times but concerned and let the customer know she needed a 30amp second breaker added to a main and run made to unit to do it correctly..

good thing the 10KW and blower on one breaker and 5 kw on the other so i can leave it OFF and let the customer decide if she runs it or not..

so

a. run it at 15kw on 60am current breaker whats the opinion?

B. can a 70amp breaker replace the 60amp and how much will that effect the wiring?

C obviously keep it on 10KW at 45.8 amp draw on 60amp main and she understands adding the 2nd breaker is only correct way to do it.i noted all that on her final invoice but wanted to hear from those more experienced in Electrical ..


let me have it advice??

[VTP99]

I would have disabled the 5K.

[BNME8EZ]

You should have a 60 A breaker for 10kW with #6 wire. If you are going to a 70 breaker you will need bigger wire. However the other issue is how are you splitting the single circuit at the panel into 2 at the unit? The lugs are rated for only 1 wire each. Your best bet would be to leave the 60 and add a 30 with #10 wire for the last 5kW.

[BNME8EZ]

As a side note I am in the process of getting a 50 A breaker for a 20 kw heat package that was on 2 - 40 breakers. The 40 could not handle the load of 10kW plus the blower and transformer.

[acguytx]

You should have a 60 A breaker for 10kW with #6 wire. If you are going to a 70 breaker you will need bigger wire. However the other issue is how are you splitting the single circuit at the panel into 2 at the unit? The lugs are rated for only 1 wire each. Your best bet would be to leave the 60 and add a 30 with #10 wire for the last 5kW.

they come into the AH and used split bolts and then ran to both 60 amp one in each lug, breakers are inside AH at heat kit. very common and acceptable to inspectors..

[acguytx]

As a side note I am in the process of getting a 50 A breaker for a 20 kw heat package that was on 2 - 40 breakers. The 40 could not handle the load of 10kW plus the blower and transformer.

well i know 20KW plus a basic PSC motors draws like 96amps most have 100amp at the main or 2 -50s..

[acguytx]

I would have disabled the 5K.

no need breaker is OFF and noted not to use or at their own risk..not disabling it our job is to enable LOL i cover it by noting it on the invoices and they sign it..not my problem after that..they are cheap anyway rather not use the extra bank..im sure if it became extremes like our last blizzard here a week ago they could flip it on here and there..

thats the odd thing the old one they were using the 15kw because it didnt have a fused nor a breaker on the heat kit just went to 60amp disconnect near the AH and over to 60amp main. Apparently it works on 60 amps even if its drawing 66amps..makes me wonder if the wire is rated at 70 on a larger wire that why i thought of putting 70 in there but lie i said left it alone..

[bkorting]

With a 3 ton air handler and matching heat pump size she does not need 15 kw unless she lives in a northern climate. If she wants 15 kw i would recommend running new wire that will support 9o amps. As a rule you should be at 80 percent load or less.

[James Colver]

You need a 30 amp circuit for the 5k circuit and a 50-60 for the 10 k strip. Don't think about putting a 70 amp breaker in the panel unless you want a fire and want the poor homeowner to come after everything you own. Good luck

[joemach]

IM HVac i know the correct way to do this but looking for alternatives. Have customer who was running 15KW ph 1 resi heat strips, so we replaced it with the same 3 ton air handler..

however the heat kit came with two service disconnect breakers which is normal but she only has a 60AMP 240V main and even though this is a X13 and uses less electricity then her old one it still draws 66amps when running all strips and blower.. i know it most likely could handle this in short run times but concerned and let the customer know she needed a 30amp second breaker added to a main and run made to unit to do it correctly..

good thing the 10KW and blower on one breaker and 5 kw on the other so i can leave it OFF and let the customer decide if she runs it or not..

so

a. run it at 15kw on 60am current breaker whats the opinion?

B. can a 70amp breaker replace the 60amp and how much will that effect the wiring?

C obviously keep it on 10KW at 45.8 amp draw on 60amp main and she understands adding the 2nd breaker is only correct way to do it.i noted all that on her final invoice but wanted to hear from those more experienced in Electrical ..


let me have it advice??

Option C

3 ton system= 36,000 BTU

10KW=34,000 BTU

That is all I ever put in with a 3 ton. Never had an issue. I live in snow country, how much heat do you really need in Dallas?

[acguytx]

Option C

3 ton system= 36,000 BTU

10KW=34,000 BTU

That is all I ever put in with a 3 ton. Never had an issue. I live in snow country, how much heat do you really need in Dallas?

i guess you missed the blizzard that hit the deep south HARD, we had like 7 days where it never got over freezing , had some single dicit lows some hit zero and it was like 4 days under 20 for lows..way lower then design temps..you re correct under normal design temp conditions 10kw is all you need however i prefer HP with it , she declined the HO and it had 15kw which i typically put in 5kw per ton but like you said have lived with 10kw until we have record low temps and people cant get their homes over 67 degrees and want to complain A LOT! LOL

I left the 10kw active switched the 5 OFF and she knows she shouldnt use it unless sits major emergency and should get an electrician to add a new run..

I was just getting some advice from more versed electricians..

[Sooty]

i guess you missed the blizzard that hit the deep south HARD, we had like 7 days where it never got over freezing , had some single dicit lows some hit zero and it was like 4 days under 20 for lows..way lower then design temps..you re correct under normal design temp conditions 10kw is all you need however i prefer HP with it , she declined the HO and it had 15kw which i typically put in 5kw per ton but like you said have lived with 10kw until we have record low temps and people cant get their homes over 67 degrees and want to complain A LOT! LOL

I left the 10kw active switched the 5 OFF and she knows she shouldnt use it unless sits major emergency and should get an electrician to add a new run..

I was just getting some advice from more versed electricians..

I don't trust customers that much my fear would be she'd flip the switch and have the inspectors knocking on my door before the fire department got on scene. Every now and then we'll get some unusually cold weather and people will complain their furnaces aren't' working right and I just tell them the systems are sized to the weather we get 99.0% of the time and if they feel a bit chilly turn on a portable heater or grab a blanket.

[hvacker]

Don't break the law. The NEC. You will be held responsible for not adhering to code.
If you leave it up to the HO to follow your advice it will be your word against the HO's.
Are you saying the structure has a 60A main or is this a feeder? I haven't seen a 60A main
in years.
If no other choice, I would physically remove a section of heat elements if possible to match
the electrical supply and not risk things HO's do. Like maybe the next owner or turning the
breaker on and forgetting.
You also don't want to be sued for installing a system incorrectly or a fire hazard. A lot of the
risk would depend on things like wire length.

It's hard to ask for an extra after a contract is signed. But it's possible.