function cmdCalc_Click(form){
     if (form.On_Load_Time.value == 0 || form.On_Load_Time.value.length == 0){
        alert ("The on load time filed can't be 0");
        form.On_Load_Time.focus();
     }
     else if (form.Off_Load_Time.value == 0 || form.Off_Load_Time.value.length == 0){
      alert ( "The off load time filed can't be 0!");
       form.Off_Load_Time.focus();
     }
     else if (form.Working_Weeks.value == 0 || form.Working_Weeks.value.length == 0){
     alert ( "The Working_Weeks filed can't be 0!");
     form.Working_Weeks.focus();
	 }
     else if (form.Working_Days.value == 0 || form.Working_Days.value.length == 0){
     alert ( "The Working Days filed can't be 0!");
     form.Working_Days.focus();
	 }
     else if (form.Motor_On_Load == 0 || form.Motor_On_Load.value.length == 0){
     alert ( "The Motor efficiency on load filed can't be 0!");
     form.Motor_On_Load.focus();
	  }
     else if (form.Motor_Off_Load.value == 0 || form.Motor_Off_Load.value.length == 0){
     alert ( "The Motor efficiency off load filed can't be 0!");
     form.Motor_Off_Load.focus();
	 }
     else if (form.Mech_On_Load.value == 0 || form.Mech_On_Load.value.length == 0){
     alert ( "The Mechanical efficiency on load filed can't be 0!");
     form.Mech_On_Load.focus();
	 }
     else if (form.Mech_Off_Load.value == 0 || form.Mech_Off_Load.value.length == 0){
     alert ( "The Mechanical efficiency off load filed can't be 0!");
     form.Mech_Off_Load.focus();
	 }
     else if (form.Total_kW.value == 0 || form.Total_kW.value.length == 0){
     alert ( "The Total kW filed can't be 0!");
     form.Total_kW.focus();
	 }
     else if (form.Hours.value == 0 || form.Hours.value.length == 0){
     alert ( "The Hours per Day filed can't be 0!");
     form.Hours.focus();
	 }
     else if (form.Cost_Elec.value == 0 || form.Cost_Elec.value.length == 0){
     alert ( "The Cost/unit of Electicity filed can't be 0!");
     form.Cost_Elec.focus();
	 }
     else {
     calculateCostElec(form);     }
     }

  function calculateCostElec(form){
    duration =    form.Working_Weeks.value * form.Working_Days.value *  form.Hours.value;
    durationOn = duration * form.On_Load_Time.value /100;
    durationOff = duration * form.Off_Load_Time.value /100;
    EffOn = (form.Motor_On_Load.value * form.Mech_On_Load.value)/10000;
    EffOff = (form.Motor_Off_Load.value * form.Mech_Off_Load.value )/10000;
    onload1 =  (form.Total_kW.value * durationOn *   form.Cost_Elec.value ) /( EffOn);
    offload1 = (form.Total_kW.value * durationOff * form.Cost_Elec.value ) / (EffOff );
    ftotal 	= Math.round(onload1 + offload1);
form.Total_Cost.value = "£" +  ftotal/100;  }