Use of Ferrules Versus Costs

Here in the United States, ferrules are not required to be used on stranded wire unless specified somewhere. Like for example if the panel were to go overseas or customer specification calls for it. When it is optional, I find it hard to validate an argument to use ferrules.

I understand why they are used in order to ensure all the strands are nice and straight and securely under the terminal to ensure a quality connection. At the same time, missing or damaged strands can be easily hidden inside the barrel of the ferrule. They can easily add $1000 of added cost to a larger panel in material and labor. On larger orders like multiple panels, that can be several thousand dollars.

How would one sell or validate the necessity of using ferrules to warrant the added costs when good craftsmanship, which I can presume we are all craftsmen, will do the job as well without the additional costs? As a supplier of service rather as a panel vendor or as maintenance personnel to an employer, the bottom dollar has to be watched like a hawk in order to stay in business. We can not always do or use what we want because its preferred, or "that's just how we did it" mentality works in a successful business.

Thoughts?

The use of ferrules is in most places I know a requirement for screw-terminals, but not a for cage-clamp terminals. Some cage clamp brands even discourage the use of ferrules. We use cage-clamp wherever we can - and what a bliss that is compared to the olden days with screw terminals. And we use cage-clamp not just for terminals, but also PLC i/o, contactors, MCCBs .. upto 4 mm² wire size. Because of that, the cost for ferrules for the few screw terminals that we still have is neglible.

Now, IF you still use olden fashioned screw terminals, then the cost of adding ferrules to the wire-ends is minimal compared to the hassle and downtime you get from not having them. Your example of that ferrules can hide a damaged strand, I find irrelevant. Inserting and removing a wire a couple of times in a screw terminal and without ferrules will certainly damage some strands a lot more.

jespermp said:

the use of ferrules is in most places i know a requirement for screw-terminals, but not a for cage-clamp terminals. Some cage clamp brands even discourage the use of ferrules. We use cage-clamp wherever we can - and what a bliss that is compared to the olden days with screw terminals. And we use cage-clamp not just for terminals, but also plc i/o, contactors, mccbs .. Upto 4 mm² wire size. Because of that, the cost for ferrules for the few screw terminals that we still have is neglible.

Now, if you still use olden fashioned screw terminals, then the cost of adding ferrules to the wire-ends is minimal compared to the hassle and downtime you get from not having them. Your example of that ferrules can hide a damaged strand, i find irrelevant. Inserting and removing a wire a couple of times in a screw terminal and without ferrules will certainly damage some strands a lot more.

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+1

Earlier this year I was commissioning a job in China, where the (Chinese) panel manufacturer had used stranded wire, cage clamp terminals, and no ferrules. I had to re-terminate every single wire landed on a terminal strip in 7 panels because on the first two, I found a 90% failure rate on the terminations. The main problem was that they had stripped the wire too short, and then pushed it into the terminal far enough that the clamp was clamping the insulation, not the conductor.

I gave the panel builder a bit of a serve over that, and had them send over some ferrules for me to re-fit. They argued that ferrules are not a requirement on stranded wires in China - which is true, both for China and Australia (and the US, by the sound of it). But had they used ferrules, we wouldn;t have had a problem. With a ferrule, you have a visual cue as to how long you need to strip the wires, and even if you're a touch short, the ferrule will save you anyway. And then you can't push a ferrule too far into a terminal like they did, because the plastic collar will stop you, and you again have a visual cue looking along the terminal strip to check that all the plastic collars are inserted about the same amount.

As the OP suggested, ultimately this one comes down to proper craftsmanship - with or without ferrules, you can do it right, or do it wrong. But whatever this panel shop saved on ferrules, even if I hadn't ultimately installed them anyway, they lost it ten times over in the hours we charged back for my time when I should have been on a laptop commissioning, and was instead in the roofspace on the tools.

The other side of the coin is the maintenance and ongoing ownership of the machine. Before I worked for an SI, I worked in maintenance, and whenever you have to pull wires in and out to troubleshoot, or make modifications, or anything else, a lack of ferrules is a huge pain. After one or two goes at it you have to re-strip it anyway because the strands are all starting to break. At that point, it always had a ferrule put on it.

If you have one of those strip-feeding hand tools, you can cut, strip and pin 50 wires in barely a couple of minutes. Well worth the small effort and cost for the poor sucker who has to keep your machine running for the next 25 years.

My objections to ferrules, spade lugs, etc. are that they are just one more connection that can fail. I am careful to use cage clamp terminal blocks to eliminate problems. It does still require care in wiring, and testing the finished product.

Just yesterday I was looking at a panel that was rebuilt and noticed that no ferrules were used. Strands of wire were sticking out and nearly shorting two neighboring connections.

The cost of the ferrule, in my opinion, pays off in the long run to whoever maintains the panel rather than whoever builds it. With all the time in the world to build a panel, I'm sure most will do a good job of it without ferrules. It's the subsequent wiring changes that will mess it up.
One way I found to alleviate this is by using knife terminal blocks that avoid to an extent having to pull the wire for troubleshooting or measurement and so on.

I want to modify my previous statement of not using ferrules with cage clamp terminals. We do use ferrules for very thin wires. For exactly the reason stated by ASF that they can be inserted too far into the terminal if there is no ferrule.
edit: It is not necessarily because the wire has not been stripped far enough. Even if stripped far enough, thin wires can curl when pushed into the terminal.

About the local installers not stripping enough of the wire: If we use local people to install our equipment, we supervise and carefully check their work in the beginning. Only when they have shown to be able to work without introducing errors are they allowed to work without supervision. In this way the final commisioning goes without a myriad of problems.

cardosocea said:

One way I found to alleviate this is by using knife terminal blocks that avoid to an extent having to pull the wire for troubleshooting or measurement and so on.

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+1
We use knife terminals for all analog sensors for exactly this reason.

All cables in my panels get ferrules - even 16 sq mm cables. Not worth the grief of 'hairies'! Does not really take long and I hate those all in one cable strippers/twisters/crimpers - they are just too slow. May I also add painful!

Not exactly on topic - but I built and programmed a panel for a customer (using ferrules - so still on topic)
And they installed it and didn't want to pay me for commissioning it. (build and supply only - strange)
They were soon on the phone saying it didn't work at all, in fact it 'was going nuts' (their words)
The funny thing is, one said 'we had to install an extra terminal as there weren't enough'
It didn't mean anything to me until I looked inside the panel.

They had missed every terminal by 1. By that I mean wire 1 was in terminal 2 and 2 in 3 and so on to the end and then the last wire was in the extra terminal they supplied with no wire on the panel side.

As I took the wires out one by one and moved them to the left, the ferrules often stayed in the terminal as they were improperly crimped. You can get pretty quickly fed up of snipe nosed pliering ferrules out of terminals.

NB: it's quite amazing that when you get the wires in the right holes how the machine works much better

If you compare screw terminals and no ferrules versus using ferrules along with Push In Terminals (cage clamp with tool-less insertion) , the time required will be less using the latter. The cost of ferrules is minimal when you buy them from the right place for about 1 US cent each.

To me the value comes from not having that strand (or "hair" as others have referred to it) that can jump over to the next terminal and leave you troubleshooting for hours. And also if that wire is removed and re-inserted just a few times, the ferrule is a real advantage.

I do recommend the use of a high quality crimper that crimps from 4 sides to make a nice square crimp. If you use the tool that only crimps from top to bottom, you can actually put them in a terminal at 90 degrees of the crimp orientation and risk de-crimping the ferrule.

Archie said:

I do recommend the use of a high quality crimper that crimps from 4 sides to make a nice square crimp. If you use the tool that only crimps from top to bottom, you can actually put them in a terminal at 90 degrees of the crimp orientation and risk de-crimping the ferrule.

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If you specify ferrules or other crimped lugs, it would be advisable to also require the use of a ratcheting crimp tool with the correct die by properly trained individuals.

Do not skimp on the ferrule either. I recently received a panel where uninsulated tops of the ferrules were exposed above the terminal blocks. Apparently the panel builder recognized this, and instead of using correctly sized ferrules, slipped wire labels over the uninsulated top. Being low voltage, this may have been effective if they heat-shrunk the label. But they did not, and some ferrules eventually shorted above the terminals.

It would also be interesting to know if the time to lose effective clamping torque by a screw terminal is better or worse with ferrules. Comparing 2-point contact with a ferrule versus multiple points across all the strands would seem to favor not using ferrules.

In my experience poor quality ferrule application has caused more grief than stray wire strands, especially in shop-fabricated panels.

I have my panel guys always twist the strands tight before inserting them.
Nothing is worse than just strip and shove into the terminal, this how you get a lot of "loose hairs".
We may also use 2 wires under a terminal...ferrules make this next to impossible,

Here's my experience and opinion.

I worked for an oem for 11 years and we had a contract to build electrical panels and enclosures for a major company that I cannot name - non disclosure agreement.

we built I would say 15,000 panels of the same thing and we never used ferrules, always used screw terminals. No issues.

I worked on one job that had a panel with clamp terminals and many of the power terminals were burnt due to arcing. Since then I refuse to use them.
we have 2 or 3 panels here that use them, but that's it. we don't let them in.

I prefer wire ferrules. I have 2 sets of the wratchet crimpers up to 16mm and they work great. No stray wires. I allow 1 minute to put them on with the wire numbers.

to each his own I guess.
james

NetNathan said:

We may also use 2 wires under a terminal...ferrules make this next to impossible,

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There are ferrules for this purpose.

But, the cage-clamp terminals, contactors, MCCBs etc. are normally always designed with double ports for each connection, so that you can conveniently loop to the next item if needed. Thus no need to put two wires in the same terminal.

JesperMP said:

There are ferrules for this purpose.

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I'm a huge ferrule supporter, but I won't use the two wire type. They bite maintenance in the rear if individual wires need to be temporarily disconnected.