I want to enlarge cable entry hole of M25 to M40. Can I do at site?

Please confirm if we do rectification in cable entry hole based on site condition cable size OD. Does its certification invalid? Do we need to go same JB under recertification?

Please advise.

 

It is theoretically possible to modify an Ex e enclosure. However, it is generally not a good idea. If you decide to go ahead, you need to remember:

- An Ex e enclosure must retain a minimum specified level of water- and dust-tightness. If you are drilling your own holes, you need to be very careful not to invalidate this requirement.

- An Ex e enclosure will have a T rating based on the maximum permitted internal power dissipation - which in turn sets limits on the maximum current that can be carried on cables. If the increase in cable size is to handle a higher current than initially intended, you need to check that you are not exceeding this limit.

There may be other points relating to the certification of your specific JB that you need to consider - check with the manufacturer.

As always, its better to do the job right the first time rather than make patch-ups. What is involved in replacing the JB with one having the correct sized openings? Another fix would be to use a transition box to change from the larger cable size to the correct one for your JB, then connect the two with a short length of the smaller size.

No matter what it costs to do the job properly, it will be a lot less than cleaning up the mess after a fire or explosion.