Southwire Multi-Range Multimeter 10031S - Perfect for RVers

 The Southwire 10031S is a basic, manual-ranging digital multimeter designed for everyday electrical troubleshooting (a good “starter/utility” meter).

What it measures (core functions)

Southwire lists 7 functions / 19 ranges, covering: AC & DC voltage, DC current, resistance, continuity, plus 1.5V and 9V battery test.

Key specs that matter in real use

• Manual ranging (you pick the range vs. auto-range).
• 2000-count LCD (basic resolution class).
• AC voltage is “average responding” (not True RMS). This can read off on non-sinewave AC (some inverters / generators).
• AC bandwidth: 45–400 Hz.
• Auto power off: ~15 minutes.
• Continuity beeper around ~30 Ω or less.
• Input impedance: ~10 MΩ on AC/DC volts.
• Voltage/current limits (important for safety)

 From the manual’s Input Limits table:

• Volts (AC/DC): up to 600 VAC RMS / 600 VDC
• mA input: fused (0.5A fast-acting, listed as 660V AC/DC fuse rating)
• 10A input: fused (10A fast-acting, plus duty-cycle limits—short bursts only at higher currents)

CAT rating note (why you may see conflicting listings):

• Southwire’s product page states CAT III 300V.
• The manual also shows the meter can measure up to 600V (max input), which is different from the measurement category rating used for transient protection.
• Bottom line: for typical RV work (12V DC and 120V AC), you’re well within both.

Accuracy (quick feel)

From the specs table (high-level):

• DC volts: as tight as ±(0.5% + 5 digits) on the 2.000V range, and ±(0.8% + 5 digits) on higher ranges.
• AC volts: listed around ±(1.2% + 10 digits) (average-responding; sinewave assumption).
• DC amps: about ±(1.0% to 2.0% + digits) depending on range.

Durability/convenience features

• Double-molded housing, drop tested to 2 meters
• Kickstand and optional magnetic hanging strap accessory
• 5-year warranty
• Southwire even lists replacement fuse part numbers (helpful if you blow one):

Is it a good meter for RV troubleshooting?

Yes—for battery voltage checks, parasitic draw basics, fuses/continuity, outlet voltage, converter output checks, etc.

Two “gotchas” for RVers:

1. Because it’s average responding (not True RMS), readings can be misleading on modified sine wave inverters or “dirty” power.
2. Being a manual range, it’s a little slower/easier to mis-set than an auto-ranging meter (especially when you’re bouncing between 12V and 120V systems). 

 That’s a solid “basic RV owner” meter for exactly that use case—12V DC, 120V AC, and resistance/continuity—as long as you set expectations and give people a simple “how to not mess this up” quick-start. 

Best for RV Use: 

• Covers the 3 checks RV owners actually do: battery/charging voltage (DCV), outlet/shore power voltage (ACV), and “is this fuse/wire/switch open?” (ohms/continuity).
• Manual ranging keeps costs down and is fine for occasional checks once they know the right ranges.
• Not True RMS usually doesn’t matter for standard campground pedestal power; it can matter on some inverters/generators (more on that below). 

The 30-second “RV Quick Start”:

Black lead in COM always.

• Red lead in VΩ jack for volts/ohms (don’t put it in the amp jack unless they’re measuring current).

1) Check 12V battery / converter charging (DC volts) 

• Dial to DCV.
• Range: 20V DC (or the next range above 15V if it’s a different scale).
• Touch probes to battery posts: red to +, black to –.

• “What numbers mean” (simple):

• Resting battery: roughly 12.6V full, ~12.2V about half, 12.0V low
• Charging: typically 13.2–14.6V depending on converter/charger mode 

2) Check 110/120V outlet or pedestal (AC volts) 

• Dial to ACV.
• Range: 200V AC (or 600V AC if they’re unsure—starting higher is safer on a manual-range meter).
• Hot-to-neutral at an outlet should be around 110–125V.
• Simple outlet sanity checks (if they’re comfortable):
• Hot-to-ground ≈ same as hot-to-neutral
• Neutral-to-ground ≈ near 0V (small is normal) 

3) Check a fuse/wire/switch (ohms or continuity)  

• Power OFF the circuit first (battery disconnect off and/or unplug shore power).
• Dial to Ω or continuity beep.
• “0–a few ohms / beep” = good connection.
• “OL / no beep” = open circuit (broken wire, blown fuse, bad switch). 

Two big safety warnings worth putting on a little card 

1. Never measure ohms/continuity on a live circuit. That’s the #1 way people blow fuses in the meter or get false readings.
2. Never try to measure AC volts with the red lead in the “A/10A” jack. That’s how meters get damaged (and it can be dangerous). 

The honest limitation (and how you can frame it)

• Not True RMS: If an RVer is measuring voltage from a modified-sine inverter (or certain generators), the AC reading may be inaccurate.  Most RVs use pure sine-wave inverters.
• How to say it: “Great for shore power and basic checks. If you’re performing a lot of inverter diagnostics, consider upgrading to a True RMS meter.