Is This Code Compliant

[Molo]

Hello,
We have an existing 100 amp panel that is overloaded. It has a 100 amp breaker in it that is feeding another 100 amp panel, and it has two 50 amp double pole breakers for stoves, and 5-15 and 2- 20 amp single pole breakers. The first panel is within 10 ft of the meter and the sub-panel is approximately 30 ft to the inside of the house.

We plan to upgrade the first panel to 200 amp and reinstall the same breakers. The service entrance cable and meter pan will also be upgraded to 200 amp. Is this code compliant on a general level? Are there any significant reasons why this is not compliant? Are there any specific reasons it is not compliant? Are any special disconnects needed?

Thanks in Advance for any replys

 

[wwhitney]

We have an existing 100 amp panel that is overloaded. It has a 100 amp breaker in it that is feeding another 100 amp panel, and it has two 50 amp double pole breakers for stoves, and 5-15 and 2- 20 amp single pole breakers.

So unless our 100 amp panel main breaker is tripping, or the panel is getting too hot, it's not overloaded in practice. It may be overloaded per an NEC calculation, but the info provided does not imply that is necessarily so.

As to the general plan, sure that's fine. If you want to reuse the breakers, you'll need to verify they are all the same manufacturer and stick with that manufacturer for the new panel. And if you are subject to the 2020 NEC (not which version is in force where you are), and it's a single or two family dwelling, you'll have to install an exterior emergency disconnect, which has various other implications.

Oh, you'll need to confirm you have appropriate grounding electrodes (e.g. 2 ground rods at least 6' apart and with at least 8' in the earth), and your grounding electrode conductor going to a metallic water service (if present) may need upsizing when going from 100A to 200A.

Cheers, Wayne

 

[Sponsor]

 

[Molo]

So unless our 100 amp panel main breaker is tripping, or the panel is getting too hot, it's not overloaded in practice. It may be overloaded per an NEC calculation, but the info provided does not imply that is necessarily so.

As to the general plan, sure that's fine. If you want to reuse the breakers, you'll need to verify they are all the same manufacturer and stick with that manufacturer for the new panel. And if you are subject to the 2020 NEC (not which version is in force where you are), and it's a single or two family dwelling, you'll have to install an exterior emergency disconnect, which has various other implications.

Oh, you'll need to confirm you have appropriate grounding electrodes (e.g. 2 ground rods at least 6' apart and with at least 8' in the earth), and your grounding electrode conductor going to a metallic water service (if present) may need upsizing when going from 100A to 200A.

Cheers, Wayne

Thank you Wayne,
Re. the exterior disconnect. Is that required because there is a subpanel, or is it required for all service upgrades when a new mater pan installed, or is there another reason it's required?

 

[wwhitney]

Re. the exterior disconnect. Is that required because there is a subpanel, or is it required for all service upgrades when a new mater pan installed, or is there another reason it's required?

2020 NEC has a new requirement for exterior emergency disconnects for 1 and 2 family dwellings. It applies in new construction and to my understanding to service upgrades. If you are under the 2017 NEC, then it wouldn't be an issue.

Cheers, Wayne

 

[Afjes]

Molo:

We have an existing 100 amp panel that is overloaded. It has a 100 amp breaker in it that is feeding another 100 amp panel, and it has two 50 amp double pole breakers for stoves, and 5-15 and 2- 20 amp single pole breakers.

Other than the fact of what you state above why do you feel you need to upgrade to 200amp service?

You can have 100amp main service and from that feed 4 100amp subpanels and still not be overloaded for your service.
What determines that you are overloaded or may be overloaded is if you do a "load calculation" which will determine what your needs are in the way of a main service.

Many DIYers are under the impression that you add up the total of your breakers which would then determine your usage. This is not the correct way to do this. A load calculation will determine what your present needs are in the way of power.

Just because you have a 100amp sub panel does not mean you are utilizing 100amps all of the time.

If you have not done a load calculation I would advise that you do so. There are many on the Net that will guide you as to what you need to enter into them for your results. It is very posible that you may not need to spend the money to upgrade to 200amps.
Please first do the load calculation. Here is a load caculator that seems to be easy for a DIYer to use. Run your numbers thru this first before you do anything.

 

[Molo]

Molo:

Other than the fact of what you state above why do you feel you need to upgrade to 200amp service?

You can have 100amp main service and from that feed 4 100amp subpanels and still not be overloaded for your service.
What determines that you are overloaded or may be overloaded is if you do a "load calculation" which will determine what your needs are in the way of a main service.

Many DIYers are under the impression that you add up the total of your breakers which would then determine your usage. This is not the correct way to do this. A load calculation will determine what your present needs are in the way of power.

Just because you have a 100amp sub panel does not mean you are utilizing 100amps all of the time.

If you have not done a load calculation I would advise that you do so. There are many on the Net that will guide you as to what you need to enter into them for your results. It is very posible that you may not need to spend the money to upgrade to 200amps.
Please first do the load calculation. Here is a load caculator that seems to be easy for a DIYer to use. Run your numbers thru this first before you do anything.

This is a good point. I looked at the calculator and will have to gather some info from the individual appliances to complete it. Based on the following info is there a possibility we may be ok or is it obvious that we will have to upgrade to a 200 amp? Currently there is a 100amp panel with a 100 amp subpanel. Between the two panels there are: 2 standard sized electric stove/ovens (each a double pole 50 amp breaker), two 8ft sections of 1500 watt electric baseboard (each on a double pole 20 amp breaker), two kitchens each with a full size refrigerator and a microwave, two bathroom circuits, 6 bedrooms, two living rooms, (lighting is all LED). There is no laundry room, and there is no garage. We would like to add a 50 gallon electric water heater. Thank you

 

[Afjes]

I would really rather not venture into "If" you would need an upgrade.
Gather the information needed for the load calculator and input the values.
If some of the appliances/devices do not mention watts or amps on their name plates use "Ohms Law" to figure it.
Take a look here for Ohms Law. This will assist you nicely.

Stay mainly with the Amps, Volts and Watts (P I E)
P (Power/watts) = I (amps) x E (volts)

This is basic once you understand it.

Example: A microwave name plate has listed on it
120V-8amps but you need to know the watts (power).
Then you calculate as: 120x8=960 watts (power)
If it had on the nameplate
1200 watts (power) - 120v
Then you calculate as: 1200 divided by 120 = 10amps

Doing a load calculation is the best way to determine if you need to upgrade your service.

Also include anything you may be thinking about installing in the future as part of your calculation.