def dict_of_load_relays(relays, buses_with_loads):
    """
    Create dictionaries of the relay keys from the
    load elements
    """
    load_relays = {k: list() for k in buses_with_loads}

    for relay_name, relay in relays.items():
        load_relay_mappings = relay['load']
        if load_relay_mappings:
            for b in load_relay_mappings:
                load_relays[b].append(relay_name)

    return load_relays