MyServer.MyClient svc = new MyServer.MyClient();
svc.ClientCredentials.Windows.AllowedImpersonationLevel = System.Security.Principal.TokenImpersonationLevel.Impersonation;
svc.ScanWS(WSID);

WSHttpBinding bind = new WSHttpBinding(SecurityMode.Message,false);
bind.Security.Message.ClientCredentialType = MessageCredentialType.Windows;
Type serviceType = typeof(MyService);
Uri serviceUri = new Uri("http://localhost:8080/");
host = new ServiceHost(serviceType, serviceUri);
host.AddServiceEndpoint(typeof(IMyService), bind, serviceUri);
host.Open();

 [OperationBehavior(Impersonation = ImpersonationOption.Required)]
        public bool ScanWS(string WSID)
        {
            try
            {
                //Если здесь запросить ServiceSecurityContext.Current.WindowsIdentity.Name то можно увидеть имя пользователя который запустил клиентское приложение
                MyDBEntities db = new MyDBEntities();
                System.Data.Objects.ObjectQuery<Workstation> ws = db.Workstations.Where("it.WSID=@wsid", new System.Data.Objects.ObjectParameter("wsid", Convert.ToInt32(WSID)));
                string WSName = ws.First().WSName;
                string spath = "\\\\" + WSName + "\\root\\cimv2";
                ManagementPath path = new ManagementPath(spath);
                ManagementScope scope = new ManagementScope(path);
                scope.Options.Impersonation = ImpersonationLevel.Impersonate;
                scope.Connect(); //- вот здесь Отказано в доступе
//......
}
catch
{
}
}