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Testing Residential Electrical Load Calculator - Need Help Testing

From a quick once-over, a few comments:

- The title says standard load calc (Article 220 Part II), but the part about HVAC references 220.83, which is the optional load calc (Article 220 Part III)
- No Table 220.45 demand factor for the lighting/general receptacles load is implemented.
- Missing option for 75% factor for appliances if 4 or more (220.53)
- The calculation for the cooking appliances does not follow 220.55. If I enter a single cooking appliance, the output should be 80% of the rating if 1.75 kW to 8.75 kW; a flat 8 kW if between 8.75 kW and 12 kW; and 8 kW * (1 + ceiling(kW - 12)*.05) for 12 kW to 27 kW.
- No extra 25% for the largest motor
- 2023 NEC 220.57 specifies a minimum 7200 VA for any EVSE.
- For the HVAC, maybe have spots for both heating and cooling loads, and a check box to specify they are non-coincident, in which case you can use the larger. Although properly implementing 220.60 is a little tricky (the code language there has been a bit garbled the last few cycles).
- And the optional load calc is probably more useful, as it is generally lower, and I think also simpler to implement.

Cheers, Wayne
 
wwhitney said:
From a quick once-over, a few comments:

- The title says standard load calc (Article 220 Part II), but the part about HVAC references 220.83, which is the optional load calc (Article 220 Part III)
- No Table 220.45 demand factor for the lighting/general receptacles load is implemented.
- Missing option for 75% factor for appliances if 4 or more (220.53)
- The calculation for the cooking appliances does not follow 220.55. If I enter a single cooking appliance, the output should be 80% of the rating if 1.75 kW to 8.75 kW; a flat 8 kW if between 8.75 kW and 12 kW; and 8 kW * (1 + ceiling(kW - 12)*.05) for 12 kW to 27 kW.
- No extra 25% for the largest motor
- 2023 NEC 220.57 specifies a minimum 7200 VA for any EVSE.
- For the HVAC, maybe have spots for both heating and cooling loads, and a check box to specify they are non-coincident, in which case you can use the larger. Although properly implementing 220.60 is a little tricky (the code language there has been a bit garbled the last few cycles).
- And the optional load calc is probably more useful, as it is generally lower, and I think also simpler to implement.
Click to expand...
Working on it. Thank you!!!
 
jar546 said:
OK, let's give that another try. Works for me now offline and online. Sorry about that.
Click to expand...
You've left the 1500 VA SABCs and laundry circuits out of the 220.42 demand calculation, but 220.52(A) and (B) specify that the 220.42 demand factors apply to them.

While unlikely, it's possible that of the Microwave, Dishwasher, Disposal and Water Heater, there are only 2, and that there are 2 appliances combined under "Other Appliances". So perhaps it would be better to label these as "Appliance 1 (e.g. Microwave), "Appliance 2 (e.g. Dishwasher)", etc, still leaving the fifth field for all other appliances combined. Along with checking that none of the first four entries are zero if the fifth entry is non-zero.

On the cooking equipment, it's not actually possible to do the 220.55 calculation without knowing the number of appliances. If I have an 8 kW cooktop and a 4 kW oven, that's 12 kW * 65% = 7.8 kW (column B row 2), while a single 12 kW range is 8 kW (column C row 1).

Possibly more later, have to go now.

Cheers, Wayne
 
wwhitney said:
You've left the 1500 VA SABCs and laundry circuits out of the 220.42 demand calculation, but 220.52(A) and (B) specify that the 220.42 demand factors apply to them.

While unlikely, it's possible that of the Microwave, Dishwasher, Disposal and Water Heater, there are only 2, and that there are 2 appliances combined under "Other Appliances". So perhaps it would be better to label these as "Appliance 1 (e.g. Microwave), "Appliance 2 (e.g. Dishwasher)", etc, still leaving the fifth field for all other appliances combined. Along with checking that none of the first four entries are zero if the fifth entry is non-zero.

On the cooking equipment, it's not actually possible to do the 220.55 calculation without knowing the number of appliances. If I have an 8 kW cooktop and a 4 kW oven, that's 12 kW * 65% = 7.8 kW (column B row 2), while a single 12 kW range is 8 kW (column C row 1).

Possibly more later, have to go now.

Cheers, Wayne
Click to expand...
Thanks for the feedback. I’ve been struggling with this and spent a few hours on it. If I don’t get this straightened out within a reasonable amount of time spent on it, I’m going to probably abandon it. I even looked at some Excel spreadsheets, but I’ve noticed that some of those are actually incorrect also. Honestly, most of the time what we get are the panel schedules with the wattages and then it gets calculated per panel and then we add up all the panels, especially for commercial. It’s not often that we’re seeing the actual calculation sheet like I’m trying to provide anymore.
 
jar546 said:
This is a work in progress. Can someone run a load or two and check for accuracy? I'm burned out right now and can't be looking at the same thing again.

Click to expand...
I like it, if I can be petty... there are some important details which may make inspector decisions incorrect.
I was doing loads for data centers, racks in data centers ...
I was a EE before I switched to the (at the time) new program of Computer Engineer (BSCE) as a junior.
And I was a specialist at Southern California Edison for deregulation

Speaking as an engineer, just putting numbers in misguides the student.
There is a lot of information, which is left out, which the student should be aware of, and inspectors should be minimally exposed to engineering practices so they are not so rigid.

What is the definition of VA, I have seen at least three different definitions by manufacturers. I like the rigid "volts x max amp draw by device"
Since Ameren allows a 200 amp 220v circuit to be overcommitted to 225 to 250 amps. Teaching inspectors that 200 amp service is rigid 200 amps is wrong.

As an engineer, I would ALLOW a peak measurement of usage on any circuit and cumulative circuit. Easily done with today's smart meters.

At Toyota north America data center, before I pointed out the problem and solution. A EE was monitoring testing and everything was overcommitted where they were right at 99% of max amps, not rated Amps. Many of the items were rated at a max but were idling 100% of the time. So they were measuring actual peak usage. I pointed out that 80% of the nodes in thier datacenter were depricated projects, thus the node SHOULD be removed. But they would not remove anything until it broke because of japanese management style.

I would include a checklist of appliances with recommended max VA for each, with instructions to verify what is the max VA for probable devices to be added:
residential fridge
residential dryer (gas)
residential dryer (electric)
microwave (how many watts)
bathroom appliances
My Phillips 220 car charger is on a 30 amp circuit and pulls less than 25 amps, so the NEC number can/should be challenged as it contradicts manufacturer's specs. When a P.E. does an official rating, who trumps the NEC arbitrary number or the manufacturer rating?
My 110 car charger runs on a 15 amp circuit and pulls less than a hair dryer. (used it before I got the 220). no way must this be rated as 7200 VA
HVAC
1 ton (max VA)
2 ton (max VA)
3 ton (max VA)
4 ton .....
Pool filter (max VA)
Pool heater (electric, gas, solar)
Jacuzzi pool filter
Jacuzzi heater (electric, gas, solar)
window unit ( modern usually works well on a shared 20 amp circuit)
HVAC heater (electric)
HVAC heater (gas) mute, because it uses less than the AC
Garage tools:
compressor (220 or 110, very different VA)
grinder
outdoor freezer/fridge
welder MIG/TIG/ARC, 220 or 110v
auto lift
garage door openers
 
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