Columns are normally fed from the nearest DU at the caravan similar to the image below.
In the first instance check that the DU has power going to it and that the MCB’s inside have not tripped. If the switches have tripped reset to on and see if they stay in position. If they keep tripping off then you will need to liaise with the local site electrician to resolve.
Generally all equipment (access points/bridges) is connected to an electrical cut out inside the base of the column fed to the IP enclosure at the top of the column. To confirm if the equipment is powered up correctly open up the column using the appropriate key. Generally there is a triangular access key that releases the inspection panel to reveal as below.
Using the volt stick check the feed coming in from the bottom of the post, the volt stick will light up if power is present. Then check the two power cables that go up the post (lighting and feed to CC enclosure) to see if power is present, again the volt stick will light up on power being present. If there is no power going up then there may be an issue with the isolator/cutout in the column (isolator example below) that will need to be examined by a suitably qualified electrician.
If the power feeds are ok the next step is to check the enclosure at the top of the post. Using ladders or a suitable platform open up the enclosure and you will see the socket inside.
You will then need to plug in a suitable socket tester to confirm that the power is reaching the socket. If not then the socket or the cable itself may be faulty. This completes checking of power.