Max Zs Values App Update for 2019

We have updated our Max Zs Values App to the new 2019 version, it now runs faster and smoother with a few added extras.

We have added an R1+R2=Zs calculator were you can calculate the R1+R2 or calculate the Zs. We know it Is an easy calculation to carry out in your head, but if you are calculating or verifying many circuits one after another this can save you a lot of time. 

You can input your Ze once and then edit the R1+R2 value for each calculation. Or if calculating the R1+R2 then input the Ze once and edit the Zs for each calculation.

Tables for BS EN 60947-2 MCCB’s

We have added some more manufacturer MCCB Zs tables for 60947-2 devices. As the maximum Zs for MCCB’s vary between manufactures we have added some more manufacture BS EN 60947-2 max zs tables.

TT Earthing RCD Max Zs

We have also included a helpful calculator for RCD max Zs values in TT Earthing Systems. Select your RCD operating current, then choose your nominal voltage and the RCD max Zs value will be shown.

DNO Maximum Ze Values

From the Max Zs menu select Max DNO Ze values to display the maximum permitted Ze values for earthing systems, TT, TN-S and TN-C-S (PME).

PME = Protective Multiple Earthing.

Earthing System	Maximum Permitted Ze
TN-C-S (PME)	0.35 Ω
TN-C	0.8 Ω
TT	*20 Ω

*For TT earthing systems the value to earth should be as low as practically possible, a value exceeding 200 Ω could become unstable.

110V Zs Values

For 110 volt maximum Zs values we a have a specific calculator which is included within the Max Zs Values app.

​”Uo of 55v and 63.5v”, select your nominal voltage “Uo 55 volts” for single phase or “Uo 63.5 volts” for three phase, select your protective device from the drop down menu, then select the protective device rating to display the maximum Zs value for a 5 second disconnection time @ 100% and temperature adjust values (80%).

Uo = Voltage to earth.