diff --git a/nemreader/split_days.py b/nemreader/split_days.py
index 523bc23..6626017 100644
--- a/nemreader/split_days.py
+++ b/nemreader/split_days.py
@@ -164,6 +164,12 @@ def make_set_interval(
 
         if r.uom and r.uom[-1].lower() == "h":
             grp_value = sum([x.read_value for x in grp_readings])
+        elif r.uom and r.uom[-1].lower() == "v":
+            # Exclude zero values to avoid ~120V when averaging 0 and 240 V
+            voltages = [x.read_value for x in grp_readings if x.read_value]
+            if not voltages:  # If all zero then that is okay
+                voltages = [x.read_value for x in grp_readings]
+            grp_value = mean(voltages)
         else:
             grp_value = mean([x.read_value for x in grp_readings])
 
diff --git a/requirements.txt b/requirements.txt
index edcef9f..0d79a5a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -7,9 +7,9 @@ click==8.1.7
     #   typer
 click-default-group==1.2.4
     # via sqlite-utils
-coverage==7.5.3
+coverage==7.6.0
     # via pytest-cov
-exceptiongroup==1.2.1
+exceptiongroup==1.2.2
     # via pytest
 iniconfig==2.0.0
     # via pytest
@@ -17,12 +17,12 @@ markdown-it-py==3.0.0
     # via rich
 mdurl==0.1.2
     # via markdown-it-py
-mypy==1.10.0
+mypy==1.10.1
 mypy-extensions==1.0.0
     # via mypy
-numpy==1.26.4
+numpy==2.0.0
     # via pandas
-packaging==24.0
+packaging==24.1
     # via pytest
 pandas==2.2.2
 pluggy==1.5.0
@@ -31,7 +31,7 @@ pluggy==1.5.0
     #   sqlite-utils
 pygments==2.18.0
     # via rich
-pytest==8.2.1
+pytest==8.2.2
     # via pytest-cov
 pytest-cov==5.0.0
 python-dateutil==2.9.0.post0
@@ -42,7 +42,7 @@ pytz==2024.1
     # via pandas
 rich==13.7.1
     # via typer
-ruff==0.4.6
+ruff==0.5.2
 shellingham==1.5.4
     # via typer
 six==1.16.0
@@ -58,7 +58,7 @@ tomli==2.0.1
     #   mypy
     #   pytest
 typer==0.12.3
-typing-extensions==4.12.0
+typing-extensions==4.12.2
     # via
     #   mypy
     #   typer