diff --git a/.obsidian/plugins/recent-files-obsidian/data.json b/.obsidian/plugins/recent-files-obsidian/data.json
index 73f37fd..5401b02 100644
--- a/.obsidian/plugins/recent-files-obsidian/data.json
+++ b/.obsidian/plugins/recent-files-obsidian/data.json
@@ -1,9 +1,29 @@
 {
   "recentFiles": [
+    {
+      "basename": "fire-alarm",
+      "path": "fire-alarm.md"
+    },
+    {
+      "basename": "hvac-calculations",
+      "path": "hvac-calculations.md"
+    },
+    {
+      "basename": "alternating-current",
+      "path": "alternating-current.md"
+    },
     {
       "basename": "conductor-sizing",
       "path": "conductor-sizing.md"
     },
+    {
+      "basename": "full-takeoff",
+      "path": "full-takeoff.md"
+    },
+    {
+      "basename": "electrical",
+      "path": "electrical.md"
+    },
     {
       "basename": "README",
       "path": "README.md"
@@ -12,14 +32,6 @@
       "basename": "stochastic-branch-takeoff",
       "path": "stochastic-branch-takeoff.md"
     },
-    {
-      "basename": "electrical",
-      "path": "electrical.md"
-    },
-    {
-      "basename": "full-takeoff",
-      "path": "full-takeoff.md"
-    },
     {
       "basename": "nfpa-70_314_boxes",
       "path": "nfpa-70_314_boxes.md"
@@ -52,10 +64,6 @@
       "basename": "nfpa-70_110_requirements-for-electrical-installations",
       "path": "nfpa-70_110_requirements-for-electrical-installations.md"
     },
-    {
-      "basename": "alternating-current",
-      "path": "alternating-current.md"
-    },
     {
       "basename": "construction-estimating",
       "path": "construction-estimating.md"
@@ -191,14 +199,6 @@
     {
       "basename": "functional-labor-factoring",
       "path": "functional-labor-factoring.md"
-    },
-    {
-      "basename": "gold-plating",
-      "path": "gold-plating.md"
-    },
-    {
-      "basename": "functional-estimating",
-      "path": "functional-estimating.md"
     }
   ],
   "omittedPaths": [],
diff --git a/alternating-current.md b/alternating-current.md
index cf271b4..9591699 100644
--- a/alternating-current.md
+++ b/alternating-current.md
@@ -36,27 +36,32 @@ The voltage measured between any line and neutral is called phase voltage.
 208Y/120V
 480Y/277V
 
+In a 3-phase wye connected system,
+ignoring the difference in voltage,
+is voltage drop calculated differently
+between a line to line load and a line to neutral load
+
 ### Voltage Systems
 
 120/240V 1-Phase 3-Wire:
-- 120V 1-Phase 2-Wire # Line to Neutral
-- 240V 1-Phase 2-Wire # Line to Line
+* 120V 1-Phase 2-Wire # Line to Neutral
+* 240V 1-Phase 2-Wire # Line to Line
 
 120/208V 3-Phase 4-Wire:
-- 120V 1-Phase 2-Wire # Line to Neutral
-- 208V 1-Phase 2-Wire # Line to Line
-- 208V 3-Phase 3-Wire # Line to Lines
+* 120V 1-Phase 2-Wire # Line to Neutral
+* 208V 1-Phase 2-Wire # Line to Line
+* 208V 3-Phase 3-Wire # Line to Lines
 
 277/480V 3-Phase 4-Wire:
-- 277V 1-Phase 2-Wire # Line to Neutral
-- 480V 1-Phase 2-Wire # Line to Line
-- 480V 3-Phase 3-Wire # Line to Lines
+* 277V 1-Phase 2-Wire # Line to Neutral
+* 480V 1-Phase 2-Wire # Line to Line
+* 480V 3-Phase 3-Wire # Line to Lines
 
 wiring-configurations:
-- 1-Phase 2-Wire # Line to Neutral or Line to Line
-- 1-Phase 3-Wire # Line to Line and Line to Neutral
-- 3-Phase 3-Wire # Line to Lines
-- 3-Phase 4-Wire # Line to Lines and Line to Neutral
+* 1-Phase 2-Wire # Line to Neutral or Line to Line
+* 1-Phase 3-Wire # Line to Line and Line to Neutral
+* 3-Phase 3-Wire # Line to Lines
+* 3-Phase 4-Wire # Line to Lines and Line to Neutral
 
 ## Active and Reactive Power
 
@@ -65,27 +70,27 @@ and the electromagnetic "inertia" of inductance and capacitance,
 inherent of all matter,
 the power in an AC circuit is divided into two components:
 
-- **Active Power**
+* **Active Power**
   (abbreviated $P$, measured in watts)
-  also known as real power, is power that *does work*. 
+  also known as real power, is power that _does work_.
 
-- **Reactive Power**
+* **Reactive Power**
   (abbreviated $Q$, measured in volt-amperes reactive (VAR))
   transfers no net energy to the load.
 
 derived from these components are others:
 
-- **Complex Power**
+* **Complex Power**
   (abbreviated $S$, measured in volt-amperes (VA))
   is the vector sum of the active and reactive components.
   It is "complex" because it exists on the real and imaginary axes
   of active and reactive power respectively.
 
-- **Apparent Power**
+* **Apparent Power**
   (abbreviated $|S|$, measured in volt-amperes (VA))
   is the magnitude of the complex power vector.
 
-- **Power Factor**
+* **Power Factor**
   (abbreviated $\text{PF}$, unitless)
   is the ratio of active power to apparent power.
 
@@ -97,16 +102,3 @@ $$
 
 Capacitance and inductance can both be measured in VAR,
 but their effects cancel each other out rather than add.
-
-## Motors
-
-1hp = 746 watts
-
-full-load current (FLC) / full-load amperes (FLA)
-
-minimum circuit ampacity (MCA)
-
-$$
-\text{MCA} = 1.25 \times \text{FLC}
-$$
-
diff --git a/conductor-sizing.md b/conductor-sizing.md
index fb5b439..443b585 100644
--- a/conductor-sizing.md
+++ b/conductor-sizing.md
@@ -116,28 +116,45 @@ either for spec requirements or conduit fill considerations.
 ## Voltage Drop
 
 $$
-V_d = I \times R \times L \times M
+Z = R \cos(\theta) + X \sin(\theta)
 $$
 
 where
-* $V_d$ = Voltage Drop in volts ($V$)
-* $I$ = Current in Amperes ($A$)
-* $R$ = Feeder linear resistance in ohms per foot ($VA^{-1}\text{ft}^{-1}$)
+* $Z$ = Effective impedance
+* $R$ = AC resistance
+* $X$ = Reactance
+* $\theta$ = Power factor angle = $\arccos(PF)$
+
+> [!info] 1-Phase, Line to Neutral Voltage Drop
+>
+> $$
+> \Delta V_{LN} = I \times Z \times 2L
+> $$
+
+> [!info] 1-Phase, Line to Line Voltage Drop
+>
+> $$
+> \Delta V_{LL} = \sqrt{3} \times I \times Z \times 2L
+> $$
+
+> [!info] 3-Phase Voltage Drop
+>
+> $$
+> \Delta V_{3\phi} = \sqrt{3} \times I \times Z \times L
+> $$
+
+where
+* $\Delta V$ = Voltage drop in volts ($V$)
+* $I$ = Current in amperes ($A$)
 * $L$ = Length of wire one way in feet ($\text{ft}$)
-* $M$ = Multiplier
-  * $2$ for 1-phase
-  * $\sqrt{3}$ for 3-phase
 
 It is often more useful to know the maximum length
 a certain wiring configuration is suitable for.
 
 $$
-L = \frac{ V_d }{ I \times M } \times \frac{1}{R}
+L = \frac{ \Delta V }{ I \times M } \times \frac{1}{Z}
 $$
 
-* $L$ = Max length of wire one way in feet ($\text{ft}$)
-* $\frac{ V_d }{ I \times M }$ = Max circuit resistance in ohms ($VA^{-1}$)
-
 > [!info] Ohm's Law
 >
 > $$
@@ -148,6 +165,24 @@ $$
 > "Current" is not the OCPD rating,
 > but the actual load.
 
+## Parallel Runs
+
+The equivalent resistance of parallel resistances is given by
+
+$$
+\frac{1}{R_{\text{eq}}} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3} + \dots
+$$
+
+For $P$ parallel resistances of value $R$
+
+$$
+\begin{align*}
+\frac{1}{R_{\text{eq}}} &= P \times \left(\frac{1}{R}\right) \\
+                        &= \frac{P}{R} \\
+          R_{\text{eq}} &= \frac{R}{P}
+\end{align*}
+$$
+
 ## Transformers
 
 $$
@@ -159,21 +194,14 @@ $$
 * $V$ = feeder voltage
 * $E$ = efficiency
 
-## Parallel Runs
+## Motors
+
+1 electric horsepower = 746 watts
+
+full-load current (FLC) / full-load amperes (FLA)
+
+minimum circuit ampacity (MCA)
 
 $$
-\frac{1}{R_{\text{eq}}} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3} + \dots
+\text{MCA} = 1.25 \times \text{FLC}
 $$
-
-where $R_1 = R_n$:
-
-$$
-\begin{align*}
-\frac{1}{R_{\text{eq}}} &= P \times \left(\frac{1}{R_1}\right) \\
-                        &= \frac{P}{R_1} \\
-          R_{\text{eq}} &= \frac{R_1}{P}
-\end{align*}
-$$
-
-where
-* $P$ = Number of parallel runs
diff --git a/electrical.md b/electrical.md
index 284f1cd..3d075b3 100644
--- a/electrical.md
+++ b/electrical.md
@@ -52,6 +52,9 @@ Wiring devices and their wall plates are a common target of [[gold-plating]].
 
 Unit condensing units
 
+Put homeruns on the `Area` of the dwelling unit.
+Put connections on the `Area` of the CU.
+
 .../`CONDENSOR HOME RUNS`
 
 .../`CU CONDENSER SLEEVE W/ FLEX - NO HMRN WIRE`
diff --git a/fire-alarm.md b/fire-alarm.md
index 3fb82b3..40e1eea 100644
--- a/fire-alarm.md
+++ b/fire-alarm.md
@@ -9,6 +9,13 @@ tags:
 
 ## Info
 
+### Fire Command Center (FCC)
+
+> [!info] Also Known As
+> Emergency Command Center (ECC)
+> Fire Alarm Command Center (FACC)
+> Fire Alarm Command Room (FACR)
+
 ## Sequence
 
 ### 1. Preparation
@@ -26,19 +33,24 @@ tags:
 
 ### 2. Takeoff
 
-#### Fire Command Center
+#### Backbone
+
+Put all backbone takeoff in the `Area` of the Fire Command Center.
+Include [[sleeving]] as necessary.
+
+##### Fire Command Center
 
 `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`HEAD END EQUIP`/`... HEAD END`
 
-#### Generator Room
+##### Generator Room
 
 `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`GENERATOR ROOM ...`
 
-#### Fire Pump Room
+##### Fire Pump Room
 
 `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`FIRE PUMP ROOM ...`
 
-#### FACR to Elevator Shafts
+##### FACR to Elevator Shafts
 
 `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`ELEV SHAFT ...`
 
@@ -57,7 +69,7 @@ Input adder length to reach the bottom of the pit
 |                             |                                |
 ```
 
-#### FACR to Elevator Control Rooms
+##### FACR to Elevator Control Rooms
 
 `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`ELEV CONTROL ROOM ...`
 
@@ -67,7 +79,7 @@ Input adder length to reach the bottom of the pit
 * Use Typicals for the vertical riser. (Ex// 10' per floor)
 * Add [[sleeving]] as necessary.
 
-#### FACR to Stairwells
+##### FACR to Stairwells
 
 This is for the Flow/Tamper modules in the stairwells
 
@@ -75,7 +87,7 @@ This is for the Flow/Tamper modules in the stairwells
 
 * Measure from the furthest end of FACR to the furthest end of the stairwell to find length
 
-#### Terminal Cabinets
+##### Terminal Cabinets
 
 `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`TERMINAL CABINET`/`ACE D ACCESSORY CABINET ENCLOSURE (2) 2" ...`
 
@@ -89,7 +101,7 @@ Vertical:
 * Use 10ft Riser in Typical
 * Add [[sleeving]] as necessary.
 
-#### Annunciator Panels
+##### Annunciator Panels
 
 > [!info] Also Known As
 > * Fire Alarm Annunciator (FAA)
@@ -99,25 +111,27 @@ Vertical:
 
 * Measure from the Fire Command Room to FAA or Lobby
 
-#### Smoke Detectors
+#### Devices
+
+##### Smoke Detectors
 
 _Design Build:_
 Count every stairwell at every level.
 
-#### Pull Stations
+##### Pull Stations
 
 _Design Build:_
 Count every stairwell at every level
 and every exterior exit.
 
-#### Flow-Tamper Switches
+##### Flow-Tamper Switches
 
 No free air. if wood frame, take off as EMT.
 
 _Design Build:_
 Count every stairwell at every level.
 
-#### Magnetic Door Holders
+##### Magnetic Door Holders
 
 `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`INDICATING DEVICES WITH WIRE - ...`/`MAGNETIC DOOR HOLDER - ...`
 
@@ -125,7 +139,7 @@ _Design Build:_
 Count every set of double doors.
 (Typical of elevator lobbies and corridors)
 
-#### Speaker Strobes
+##### Speaker Strobes
 
 _Design Build:_
 * Count every 75 ft,
@@ -135,7 +149,7 @@ _Design Build:_
 * every elevator lobby,
 * and every BOH room on the first floor and garage levels.
 
-#### Firefighter Phone System
+##### Firefighter Phone System
 
 * firefighter phone jacks
 * fire warden station
@@ -146,7 +160,7 @@ Not related to responder radio.
 
 `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`COMMUNICATION DEVICES ...`/`...`
 
-#### Fire Smoke Dampers (FSD's)
+##### Fire Smoke Dampers (FSD's)
 
 Take off both FA
 
@@ -158,4 +172,4 @@ and Electrical
 
 ### 3. Review
 
-* Sleeving
+* [[sleeving]]
diff --git a/hvac-calculations.md b/hvac-calculations.md
new file mode 100644
index 0000000..970e928
--- /dev/null
+++ b/hvac-calculations.md
@@ -0,0 +1,89 @@
+---
+id:
+aliases: []
+tags: []
+---
+# HVAC Calculations
+
+## Units
+
+### British Thermal Unit
+
+Unit of heat energy
+
+There are several definitions of the Btu,
+HVAC uses the IT definition,
+abbreviated Btu<sub>IT</sub>
+
+$$
+\begin{align*}
+1 \text{Btu}_\text{IT} &= \left( 4.1868 \times 453.59237 \times{\frac{5}{9}} \right) \text{J} \\
+&\approx 1055.056 \text{J}
+\end{align*}
+$$
+
+More common than Btu itself is
+thousand British thermal units per hour (MBH),
+a unit of power.
+
+$$
+\begin{align*}
+1 \text{MBH} &= 1000 \text{Btu/hr} \\
+&\approx 3.412 \text{W}
+\end{align*}
+$$
+
+### Ton of Refrigeration (TR or TOR)
+
+Unit of power
+
+> [!info] Also Known As
+> * refrigeration ton (RT)
+> * ton (refrigeration)
+
+$$
+\begin{align*}
+1 \text{TR} &= 12000 \text{Btu}_\text{IT}/\text{h} \\
+&\approx 3516.853 \text{W}
+\end{align*}
+$$
+
+### Cubic Feet per Minute (CFM)
+
+Unit of volumetric flow
+
+## Measures
+
+### Airflow
+
+* CFM
+
+External static pressure (ESP)
+measured in inches of water
+
+### Heating/Cooling Capacity
+
+* Tons (refrigeration)
+* MBH
+
+Entering air temperature (EAT)
+Leaving air temperature (LAT)
+Mixed air temperature (MAT)
+
+Latent heat
+Sensible heat
+
+Sensible -> dry bulb
+Latent -> wet bulb
+
+#### ???
+
+OSA EAT (F)
+EXH EAT (F)
+
+IN S.L.
+OUT ALT.
+
+### Efficiency
+
+* η (eta)