How to size cable glands—Basic knowledge

Cable Glands

The cable gland is a small part of accessories in the electrical industry. But there are many types of cable glands, and also due to different standards of threads, there are many sizes of cable glands. So if you want to install a cable gland, you need to know how to calculate the cable gland size first.

There are two ways to know the cable glands’ size.

First from threads:

From the thread type said, cable glands can make Metric cable gland, PG cable gland, NPT cable gland, and BSP (G) cable gland.

And from thread size, Metric cable gland can do from M8 to M120, and even larger cable glands in order to meet the size of the cable. In the same way, PG cable gland can do from PG7 to PG63; NPT cable gland can do from NPT1/4″ to NPT5″; BSP (G) cable gland can do from BSP1/4″ to BSP 5″.

  1. If you had an existing before designed thread hole on your equipment for a thread for example PG7 or M20*1.5, it is easy for you now, because there is an existing size for cable gland size you know it, but there is a problem, you should double check if the cable you use will be in the right size or not. Many times, people use the wrong cable size for a exist cable glands, which will cause the cable not to be locked tightly or not to be penetrated.
  2. If the equipment is a panel type, and you have just opened the hole, what can help to check the size of the gland is that you show know the outer diameter of threads, and find a matching one for it. Important thing, there is a tip for you that you can not find thread too small for the whole, the hole size can not be more than 2mm larger than the gland thread outer diameter, Or the cable gland can not tighten the equipment well. Moreover, when you check the size, you should also double check whether the cable diameter fits the gland.

On the contrary, if you have determined the size of the cable gland, but do not know how large the opening of the electrical equipment board is, you can also refer to the outer diameter size of the thread.

Second from cable size:

Sometimes if you do not know the existing cable gland thread, you can judge the gland size by cable size.

Tip: For all cable glands, when you judge the cable gland size by cable diameter size, it means the cable outer diameter size, not the square diameter size. For example, if you give a cable size of 4*1.5 mm2, not us, all cable glands suppliers will ask again for outer cable diameter again, or we can not judge the cable size.

For sizing cable gland, if by the cable size, we should classify it into different types of cables.

  1. For unarmoured cable, as long as you know the outer diameter of the cable used, and compare it with the standard cable range, you can know which size of cable gland you use. And for this type of cable gland, the cable range must be smaller than the cable gland size.
  2. For armored cable,  de-armoring is required if it is to work with an armored cable gland. Therefore, when judging the size of the armored cable joint, in addition to knowing the outer diameter of the cable, it is best to consider the outer diameter of the cable after the armor is removed. For most armored cable glands when it was developed, people have considered this problem, but sometimes when encountering customized non-standard cables, there will be a situation where the de-armored cable is too smaller or larger than the seal, resulting in the cable it doesn’t lock tightly.

If there are many usages for cable glands in your project, it must be the basic knowledge you must master about cable glands.

Of course, it is also helpful when you send an inquiry, the more detail you know, the better you can get the right cable gland to fit your electrical equipment.

However, if you want to make an inquiry about cable glands from Sanhui or not, I hope this knowledge can help you know more about cable glands.

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