Prevent cable from being pulled through hole - Page 1
Forum section: electronics / beginners

author: Jackster
author_rank: Frequent Contributor
timestamp: May 14, 2018, 09:17:30 am
content: Hi all.Having to have a cable go through the side of a electronics housing.Would love a socket for the cable to connect into but there is not enough room internally for it so having to drill a hole for the cable to come through.Obviously need something to clamp it to prevent it being pulled out.I know there is a name for this product, but I don't know what it is.Yes I zip tie would work but looking for something better..ThanksJack

author: Zero999
author_rank: Super Contributor
timestamp: May 14, 2018, 09:37:35 am
content: Tie a knot in the cable, then it can't slip through the hole.

author: Jackster
author_rank: Frequent Contributor
timestamp: May 14, 2018, 09:39:56 am
content: Quote from: Hero999 on May 14, 2018, 09:37:35 amNot enough room I am afraid.

author: Messtechniker
author_rank: Frequent Contributor
timestamp: May 14, 2018, 09:43:05 am
content: Quote from: Hero999 on May 14, 2018, 09:37:35 amNever ever do this. It's unprofessional and the housing edges maycut into the cable insulation and the is no strain relief.Use acable glandinstead.

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 14, 2018, 09:47:04 am
content: The most common solution is a strain-relief bushing, and the prominent brand is Heyco.When you use the proper size, they grip the cable so well that the cable will break before they let go.But they need exactly the right size hole and they are tricky to install/remove with ordinary pliers.https://www.heyco.com/Strain_Relief_Bushings/product.cfm?product=Original-Strain-Relief-Round-1

author: Zero999
author_rank: Super Contributor
timestamp: May 14, 2018, 09:49:52 am
content: Quote from: Messtechniker on May 14, 2018, 09:43:05 amI agree it's not ideal, but wouldn't say never. I've done it plenty of times, without any issues.

author: Brumby
author_rank: Unknown
timestamp: May 14, 2018, 10:02:30 am
content: Knot tying isn't my first choice - but it can be effective enough if the likelihood of the cable being tugged is low. Whatismost important is that the hole itself must not offer any risk to the integrity and safety to the cable.Strain relief bushings and cable glands of the correct size are much better solutions.

author: Jackster
author_rank: Frequent Contributor
timestamp: May 14, 2018, 10:18:11 am
content: Quote from: Richard Crowley on May 14, 2018, 09:47:04 amThat's the one! Could not think of what it was called.Ill try and find if they do the size I need.

author: Gyro
author_rank: Super Contributor
timestamp: May 14, 2018, 10:22:41 am
content: Nobody asked if it was a mains cable?If it is, then no way should you ever tie a knot in it! Mains cablesrequireproper strain relief to prevent tugging or chafing on the sides of the hole. That's a safety issue. [Edit: Another vital function of a strain relief is rotation prevention - that can tear internal mains wiring loose.]

author: jpanhalt
author_rank: Super Contributor
timestamp: May 14, 2018, 10:26:52 am
content: I have just used a zip tie (nylon strap). You can also wrap tape around it, use heat shrink, or any combination of the three.

author: Mr. Scram
author_rank: Super Contributor
timestamp: May 14, 2018, 10:28:46 am
content: Quote from: jpanhalt on May 14, 2018, 10:26:52 amEven Weller uses zip ties this way in their higher end stuff. If it works, I guess.

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 14, 2018, 10:41:17 am
content: Quote from: Gyro on May 14, 2018, 10:22:41 amYes that seems like common sense here in the 21st century. But back 60-80 years ago, rubber grommets and special knots were quite common with attached zip-cord power entrances. I remember seeing the special knots where you zip apart the two wires (L & N) and tie a symmetrical knot. Look at some of those videos showing vintage electronic gear.I hate attached power cords (including wall-warts and line-lumps). I take special pleasure in replacing those old crumbly grommets (and even Heyco bushings) with proper IEC 60320 panel-mount connectors. I still have a nice big bag of IEC connectors that I bought at the Tektronix surplus sales.

author: Gyro
author_rank: Super Contributor
timestamp: May 14, 2018, 01:29:20 pm
content: Me too. You can almost guarantee, the more valuable or irreplaceable the 'treasure' you're carrying, the more likely the cord is to get wrapped around your ankles!

author: bd139
author_rank: Super Contributor
timestamp: May 14, 2018, 01:33:08 pm
content: Captive leads of any kind are evil.I watched my father stand on an old radio power supply lead when he was carrying it once. Faceplanted and cracked a rib.Yes I did laugh

author: Kjelt
author_rank: Super Contributor
timestamp: May 14, 2018, 01:35:06 pm
content: Yes also often put a knot in it or used a tiewrap,it prevents the cable from being pulled out but it does not prevent the cable from being pushed inAlso in dusty environments those holes are dustcollectors.

author: rstofer
author_rank: Super Contributor
timestamp: May 14, 2018, 02:59:55 pm
content: Quote from: Richard Crowley on May 14, 2018, 10:41:17 amIt was done all the time! I remember seeing knots in the power cords to a lot of appliances, particularly things like table lamps. I thought the ARRL handbook showed how to tie the knot, many years ago. In any event, it is known as the Underwriter's Knot and there are a lot of hits on Google:https://www.google.com/search?q=ul+knotDone all the time!

author: FriedMule
author_rank: Frequent Contributor
timestamp: May 14, 2018, 03:43:22 pm
content: Could you please tell about what material the box are made of, type of cord, main / signal, how secure you want the cord (shall it hold any load, weight, bee trip secure)?

author: Electro Detective
author_rank: Super Contributor
timestamp: May 14, 2018, 11:30:30 pm
content: Quote from: Richard Crowley on May 14, 2018, 09:47:04 amThey were/are called 'Nylon Cable Gland' or 'Nylon Cable Entry Gland' the last time I bought some in a few sizes,they are very handy quick fixes, and a painless upgrade for stiff or deteriorating rubber grommet 'disater waiting to happen' devicesand yes they are tricky to remove if fitted securely, unless you have the purpose made tool,or a customized/butcheredpair of cheapie pliers or grippersFWIW if they are not a perfect fit, or loose/wonky and a suss grip, you can wrap electrical tape around the cable first to beef it up, then press down on the gland and slot it in to the chassisI have successully used this method for round holes too and it works well enough (an internal silicone gob 'may' be required for zero rotation movement) as these Nylon Cable Entry Glands are designed to stay put in oblong shaped holesIf aesthetics are involved, conceal the black electrical tape under length of the gland,or just get it sorted and then carefully trim off the excess tape for a pro lookOther cable diameter beef up methods are heatshrink or thin wall rubber tubing, but electrical tape works fine (UL listed preferably) if the cable isn't being removed or replaced.My personal preference is good quality black or grey duct tape, it's wide, performs well under the pressure, it's one solid adhesive piece that I stretch a bit for extra grip, to ensure it won't budge or go gooey over time and temperature extremesHard to put it in words, hope it made sense