You've got the right idea and are using the correct table, but let's break it down to ensure accuracy and code compliance: Individual Mobile Home Service

Each mobile home will indeed have a 125-amp main breaker. This is standard.

Total Connected Load

125 amps x 3 units = 375 amps. This represents the maximum potential load if every mobile home drew its full 125 amps simultaneously.

Applying Demand Factor

Table 550.31 in the NEC allows you to use a demand factor because it's highly unlikely all three homes will draw their maximum load at the same time. For 3 mobile homes, the demand factor is 44%.

Calculated Demand Load

375 amps x 0.44 = 165 amps. This is your calculated demand load – the load you should base your service conductor sizing on.

Conductor Sizing

You correctly calculated that you need to size the conductors for 165 amps. 1/0 AWG THHN copper is rated for 150 amps at 75°C, and 170 amps at 90°C, and 160 amps at 75°C so 1/0 is cutting it a little close. I would recommend increasing the wire to 2/0 to get an ample amperage rating. The correct installation method is to install the conductors at or above their rating, but never below.

Overcurrent Protection (Service Disconnect)

The main overcurrent device (likely a breaker) protecting the entire service should be rated no higher than the ampacity of your conductors, but is allowed to go to the next standard size up per 240.4(B) if the wire is rated adequately to handle the next standard size breaker up.

Important Considerations and Potential Issues



Continuous Load

Mobile homes often have significant continuous loads (heating, cooling, refrigeration). Remember that you must size your conductors and overcurrent protection for 125% of the continuous load.

Voltage Drop

At 165 amps, voltage drop can become a concern, especially if the distance from the meter stack to the mobile homes is significant. Check your voltage drop calculations to ensure you're within acceptable limits.

Future Expansion

Consider whether there is any chance of adding more mobile homes in the future. If so, it might be wise to upsize your service conductors now to avoid costly upgrades later.

Local Codes and Requirements

Always check with your local building department or electrical inspector. They may have specific requirements that supersede the NEC.

Neutral Conductor Sizing

Don't forget to size the neutral conductor appropriately. The NEC has rules about neutral conductor sizing, especially if you have significant nonlinear loads that create harmonics.

Disclaimer: This information is for general guidance only and does not constitute professional electrical engineering advice. Always consult with a qualified and licensed electrician for your specific project before beginning any electrical work.* Flag for review