12-17-2025, 05:04 AM
(This post was last modified: 12-17-2025, 06:14 AM by WestCoastXS.)
Hi,
I am an electrician in Canada that dabbles in smart home equipment and programming.
I wanted to get better power consumption data into my Home Assistant and eventually settled on the N20.
The N20 has two voltage inputs so should be well suited to typical residential services in North America which are usually 120/240V split phase.
That is two hot lines, each 120 volts to neutral/ground but 240V between each other.
After getting the yaml provided on this forum installed I discovered a shortcoming when used in this fashion.
The N20 uses two BL0910 chips which each have 10 current transformer inputs and 1 voltage sensing input (1 BL0910 on the N10 and 3 on the N30 which would be good for 3-phase monitoring).
Each BL0910 chip does calculations internally to provide watts and kWh but those calculations are done based on the single voltage input on each chip.
This is not a problem when one uses two current transformers, one for each hot line, but for a purely 240V load only a single current transformer is required.
Except the BL0910 chip calculates the watts based only on that single voltage input, 120V rather than 240V.
This yaml makes a few changes to tailor the firmware for typical USA/Canadian 120/240V residential services.
#1. Sensors have been renamed to aid readability.
bl0910_1_current_1 becomes CT1_1_Current
bl0910_1_power_1 becomes CT1_1_Power (or CT1_1_Power_HV when the power is based on a higher 240V circuit)
bl0910_2_power_1 becomes CT2_1_Power
The labelling on the outside of the unit lists CT1 to 11 and CT11-20 but I believe retaining the separation between BL0910 chip #1 and chip #2 is still important conceptually so went with CT1 1-10 and CT2 1-10.
#2 The renaming results in reordering of the entities in Home Assistant. Originally it would list currents 1-10, then watts 1-10, etc. Now all 3 sensors for each input is grouped and easily visible at a glance rather than scrolling 10 entries down.
#3 Reconfigured to use wifi rather than ethernet. Deleted unnecessary(?) text sensors for unused IP addresses.
#4 The OLED screen. Originally it only displayed the unit's IP address.
Now it shows the IP address, Line 1 & 2 voltages, Line-to-line voltage, L1 watts and L2 watts.
For Line 1 & 2 watts I have CTs on my main panel feeder to get the whole house consumption. If you do not have CTs this could be changed to a specific load or commented out.
#5 This is one of the important ones. A sensor has been added that adds together voltage 1 and voltage 2 to get the Line-to-Line voltage. This is trivial to do with a helper in Home Assistant but having a dedicated sensor is nice and is also vital for the next change.
#6 I've added commented-out sections for each current sensor input that multiply the current by the Line-to-Line voltage for 240V loads using single current transformers.
Simply delete or comment out the original sensor entry for 120V loads and uncomment the 240V entry.
The new entities add "HV" to their name to indicate the watts are derived from 240V rather than 120V.
#7 At this time I have not looked into a way to fix the kWh sensors to accommodate 240V loads but I suspect it should be possible.
In the meantime I've added comments indicating the kWh sensors should be commented out if a single CT is used for a 240V load.
kWh tracking is also trivial in Home Assistant so I'm not in a hurry to figure this one out.
If anyone has feedback or modifications please share here.
Please give credit if my modified yaml is shared elsewhere. Thank you
I am an electrician in Canada that dabbles in smart home equipment and programming.
I wanted to get better power consumption data into my Home Assistant and eventually settled on the N20.
The N20 has two voltage inputs so should be well suited to typical residential services in North America which are usually 120/240V split phase.
That is two hot lines, each 120 volts to neutral/ground but 240V between each other.
After getting the yaml provided on this forum installed I discovered a shortcoming when used in this fashion.
The N20 uses two BL0910 chips which each have 10 current transformer inputs and 1 voltage sensing input (1 BL0910 on the N10 and 3 on the N30 which would be good for 3-phase monitoring).
Each BL0910 chip does calculations internally to provide watts and kWh but those calculations are done based on the single voltage input on each chip.
This is not a problem when one uses two current transformers, one for each hot line, but for a purely 240V load only a single current transformer is required.
Except the BL0910 chip calculates the watts based only on that single voltage input, 120V rather than 240V.
This yaml makes a few changes to tailor the firmware for typical USA/Canadian 120/240V residential services.
#1. Sensors have been renamed to aid readability.
bl0910_1_current_1 becomes CT1_1_Current
bl0910_1_power_1 becomes CT1_1_Power (or CT1_1_Power_HV when the power is based on a higher 240V circuit)
bl0910_2_power_1 becomes CT2_1_Power
The labelling on the outside of the unit lists CT1 to 11 and CT11-20 but I believe retaining the separation between BL0910 chip #1 and chip #2 is still important conceptually so went with CT1 1-10 and CT2 1-10.
#2 The renaming results in reordering of the entities in Home Assistant. Originally it would list currents 1-10, then watts 1-10, etc. Now all 3 sensors for each input is grouped and easily visible at a glance rather than scrolling 10 entries down.
#3 Reconfigured to use wifi rather than ethernet. Deleted unnecessary(?) text sensors for unused IP addresses.
#4 The OLED screen. Originally it only displayed the unit's IP address.
Now it shows the IP address, Line 1 & 2 voltages, Line-to-line voltage, L1 watts and L2 watts.
For Line 1 & 2 watts I have CTs on my main panel feeder to get the whole house consumption. If you do not have CTs this could be changed to a specific load or commented out.
#5 This is one of the important ones. A sensor has been added that adds together voltage 1 and voltage 2 to get the Line-to-Line voltage. This is trivial to do with a helper in Home Assistant but having a dedicated sensor is nice and is also vital for the next change.
#6 I've added commented-out sections for each current sensor input that multiply the current by the Line-to-Line voltage for 240V loads using single current transformers.
Simply delete or comment out the original sensor entry for 120V loads and uncomment the 240V entry.
The new entities add "HV" to their name to indicate the watts are derived from 240V rather than 120V.
#7 At this time I have not looked into a way to fix the kWh sensors to accommodate 240V loads but I suspect it should be possible.
In the meantime I've added comments indicating the kWh sensors should be commented out if a single CT is used for a 240V load.
kWh tracking is also trivial in Home Assistant so I'm not in a hurry to figure this one out.
If anyone has feedback or modifications please share here.
Please give credit if my modified yaml is shared elsewhere. Thank you