def plot_line_power(obj, results, hour, ax=None):
    '''
    obj: case or network
    '''

    if ax is None:
        fig, ax = plt.subplots(1, 1, figsize=(16, 10))
        ax.axis('off')

    case, network = _return_case_network(obj)

    network.draw_buses(ax=ax)
    network.draw_loads(ax=ax)
    network.draw_generators(ax=ax)
    network.draw_connections('gen_to_bus', ax=ax)
    network.draw_connections('load_to_bus', ax=ax)

    edgelist, edge_color, edge_width, edge_labels = _generate_edges(results, case, hour)
    branches = network.draw_branches(ax=ax, edgelist=edgelist, edge_color=edge_color, width=edge_width, edge_labels=edge_labels)

    divider = make_axes_locatable(ax)
    cax = divider.append_axes('right', size='5%', pad=0.05)
    cb = plt.colorbar(branches, cax=cax, orientation='vertical')
    cax.yaxis.set_label_position('left')
    cax.yaxis.set_ticks_position('left')
    cb.set_label('Loading Factor')

    return ax
obj: case or network