Must unused cable-wires be terminated ? And can I use splicing connectors for that ?

JesperMP · Apr 6, 2021

Hi.

I always do my best to terminate all cable wires, including unused wires.
But I find that it gets difficult when for example I have specified a 10-wire cable, and have prepared 10 terminals in the control cabinet that I supply and the customer who has to supply the cables, installs a 12-wire cable because thats what he has available (*). Now there are 2 wires with nowhere to go.
Is this covered somewhere in EN60204-1 ?
And can I use splicing terminals such as Wago 221-412, or must I retrofit permanently installed terminals for the extra wires ?

What do you do ?
Opinions most welcome..

*: Actually, it is not uncommon that if he has a 20-wire cable or 24-wire, then that is what he will install, just because he cant be bothered to get the correct cable, no matter that we send a cable list months in advance.

Bobobodopalus · Apr 6, 2021

We use heat shrink end caps for un-terminated wires, from what out electrician tells me you can leave 24V wires completely un-terminated (non-atex) and we heat shrink any others, we do this for ATEX areas so i assume that it should be fine for any install

mylespetro · Apr 6, 2021

I'm sure it violates code, but I often see spare conductors with electrical tape wrapped around the ends and either spooled in the bottom of the cabinet or coiled up inside wire duct. Not ideal in my opinion, I'd rather see all conductors landed on terminal blocks, but that rarely happens in my experience.

dogleg43 · Apr 6, 2021

mylespetro said:
I'm sure it violates code, but I often see spare conductors with electrical tape wrapped around the ends and either spooled in the bottom of the cabinet or coiled up inside wire duct. Not ideal in my opinion, I'd rather see all conductors landed on terminal blocks, but that rarely happens in my experience.

In my experience, spares are labeled on both ends and left unterminated in the panel. Usually the spare wires are left long enough to be terminated anywhere in the panel.

If a spare wire needs to be used then it’s long enough to be terminated in the proper location and not on a random terminal somewhere else in the panel.

plvlce · Apr 6, 2021

dogleg43 said:
In my experience, spares are labeled on both ends and left unterminated in the panel. Usually the spare wires are left long enough to be terminated anywhere in the panel.

If a spare wire needs to be used then it’s long enough to be terminated in the proper location and not on a random terminal somewhere else in the panel.

This is what I usually see as well.

Bit_Bucket_07 · Apr 6, 2021

mylespetro said:
I'm sure it violates code, but I often see spare conductors with electrical tape wrapped around the ends and either spooled in the bottom of the cabinet or coiled up inside wire duct. Not ideal in my opinion, I'd rather see all conductors landed on terminal blocks, but that rarely happens in my experience.

My understanding is that it only violates code if the spare wire ends are not taped.

JesperMP · Apr 7, 2021

Thanks for the feedback guys.

Dont like it when people tape wire ends together. It tends to unwrap over time and leave a mess.

I have since the start of the thread been informed that in EN 60204-1 chapter 13.4.7 it is stated that unused wires must be isolated so that it is not possible to touch anything that can conduct a voltage.

Bobobodopalus said:
We use heat shrink end caps for un-terminated wires, from what out electrician tells me you can leave 24V wires completely un-terminated (non-atex) and we heat shrink any others, we do this for ATEX areas so i assume that it should be fine for any install

If a wire is connected to 24V at one end, is it allowed to be uninsulated at the other end ? It may not cause a person to be electrocuted, but it may cause sparks that can lead to many other problems. According to EN 60204-1 it is definitely not allowed.

I like the idea of the shrink end caps. I think I will pursue that solution.

Ronnie Sullivan · Apr 7, 2021

They are just spares.
Not terminated at either end but there for just in case.
5 years down the line, we need another sensor here.
Ah, we have 5 spare wires taped up at each end.

drforsythe · Apr 7, 2021

I do not know if there is any requirement to terminate or cap / tape off, but I highly recommend it. Many years ago I received a mild shock when the installers of a servo system did not terminate or insulate the ends of unused brake conductors in the servo power cable. Whenever the servo was enabled, voltage was induced in the unused wires. Based on what I see here in the US, it is not a requirement to terminate or insulate the ends, but it is definitely a good practice.

Liam Moran · Apr 7, 2021

I always install terminals to terminate every multicore cable at each end. Starting at 1,2,3 and so on for the multicores to be terminated. I always allow extra terminals in case a cable with more cores is installed or at least space to do so. I do all my patching on the panel side of the terminals. I also allow 30% minimum spare cores at the build stage. While these multicores are being installed all the installation Electrician has to do is connect core 1 to terminal 1, 2 to 2 and so on. There are always additional devices added in while commissioning for a variety of reasons. It is very convenient to have every conductor terminated at each end so you dont have to waste time poking through trunkings to find spare cores. A little extra money spent on terminals can pay you back big time.

alive15 · Apr 7, 2021

Wire caps are the way to go? Along with labeling the wire as spare for future expansion? I think the caps work better than the tape. Just screw the cap on and leave it, no need for heat shrink or messing with tape trying to get it cover up the exposed wire properly.

mad4x4 · Apr 12, 2021

Spares should be left either capped or un-capped but dressed neatly to the bottom of the panel.

On occasions, clients may ask for "full" termination to ground-bar or terminals.

"Dressed" would be neatly bundled together with other cores from the same cable correctly numbered and the Ty- wrapped into the bottom snaking spare length left and right. Capping will be heatshrink. Each Cable bundle separate so you can easily identify spares. Spares should be of reasonable length. Insulating tape is not acceptable.

mad4x4 · Apr 12, 2021

alive15 said:
Wire caps are the way to go? Along with labeling the wire as spare for future expansion? I think the caps work better than the tape. Just screw the cap on and leave it, no need for heat shrink or messing with tape trying to get it cover up the exposed wire properly.

Those "Screw" on cap/cable joiners should be banned. Worst invention ever.

If you must use something use a WAGO https://www.screwfix.com/p/wago-32a-3-way-lever-connector-50-pack/2803r

JesperMP · Apr 12, 2021

Cables are labelled already, and the wires are either numbered or color coded.
No need for additional labelling of spare wires.
(are you guys using cables with wires that are not numbered or color coded !? *)
Will definitely go for the shrink end-caps to neatly finish and isolate the spare wires.
Tying the wires to the wire duct wont survive the first time someone has to access the wire duct.

*: The only reason that it could be necessary to add extra labelling is if the wire numbers have come off. Something that we see with lowcost cables.

JesperMP · Apr 12, 2021

I also do not get the idea that tying the spares wires to the wire duct somehow equates to that the wires are isolated. How do you know that the other end of the wire is not providing a dangerous voltage ?

edit, quote from post #7:

JesperMP said:
I have since the start of the thread been informed that in EN 60204-1 chapter 13.4.7 it is stated that unused wires must be isolated so that it is not possible to touch anything that can conduct a voltage.

I have emphasized the "not possible to touch anything that can conduct a voltage".

Must unused cable-wires be terminated ? And can I use splicing connectors for that ?

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