Sexual - Still makes me tingle

[Tiny Spark]

It's like glanding an SWA onto galvanised trunking, you wouldn't fit a banjo then would you?

It depends, If I am using the SWA as the earth or I cant banjo it the other end of the cable for some reason then I will banjo it to the galv trunking.
I have always been of the opinion that even if you dont technically need it if it is there why not fit it?
Unless of course it means running in 20m of earth single or it would look stupid or out of place but thats a different kettle of fish.

 

[a1guvner]

Banjo's?

Good spot. That's the isolated end

 

[davesparks]

It depends, If I am using the SWA as the earth or I cant banjo it the other end of the cable for some reason then I will banjo it to the galv trunking.
I have always been of the opinion that even if you dont technically need it if it is there why not fit it?
Unless of course it means running in 20m of earth single or it would look stupid or out of place but thats a different kettle of fish.

I don't get it, if you drill teh hole the right size and tighten the locknut properly then that makes a good metal to metal connection so why the banjo?
And what do you do with the banjo, just stick a bolt through it to hold it to the trunking?

 

[Tiny Spark]

Nope, I put a bolt through with a crimped wire attached and run to the nearest earth point.
Doesn't everyone?? :s

The purpose being to ensure it is earthed correctly.
After all you are assuming that the trunking is correctly earthed, which from my experience its not!

 

[davesparks]

But the trunking is your CPC, why on earth would it not be earthed?

Why would you install a seperate earth wire inside the trunking which has a csa a few orders of magnitude bigger?

 

[Tiny Spark]

I was always taught its good practice.

Just to play devils advocate if you were to install a armoured into a galv trunking do you go and check that every screw and bond is in place? Can you guarantee that nobody has come along and modified it, removed a link? Hell I have seen a few that were not bonded at all!

Like I said for the sake of drilling a 6mm hole (which is the size of a pilot drill for most hole saws) and putting a bolt and crimp on whats the harm?

I agree they are not really needed normally but I can say its there.
Ime sure there used to be a reg that said a SWA had to be banjo's at least one side anyway?

 

[davesparks]

If it is existing trunking and it is not in acceptable condition then I would not be glanding an SWA onto it my installation would not be compliant.
Steel trunking must be effectively earthed in its entirety, if it is not then it does not comply.

 

[Tiny Spark]

Ok I will give you a prime example,

I did some work in a office, The desks had a 2x4 Metal powder coated galv compartment trunking drop to each row going under them, They were fed from a SWA fed from a board half way down the office.

So I linked out each section with a link. So where was I meant to earth it?
I could rely on just the 6mm crimped lugs screwed to each section of the trunking and wired into a socket, But I would rather Banjo the gland as well just to be on the safe side.

At the end of the day I would rather put that extra earth path in as its a doddle to do and doesnt take me any more significant time.
If you dont want to I wont hold it against you

 

[davesparks]

Powder coated trunking is a little different, I would be looking at an additional connection to the gland, the same as with a painted surface.
I would use an earth nut or a CMP ciel type gland for preference over a banjo.

My earlier comments have all been about bare metal, apologies if that was not clear.

To be honest I prefer to screw the gland in to a flange coupler and attach that to the trunking with a serrated washer than just attaching the gland straight to the trunking anyways.

 

[Tiny Spark]

Thats fair enough, Like I said horses for courses
Ive always fancied trying one of them Pirhana nut things but never been given one to try out!

 

[davesparks]

Thats fair enough, Like I said horses for courses
Ive always fancied trying one of them Pirhana nut things but never been given one to try out!

They are much better than relying on the bog-roll thin banjos that turn up in gland packs these days.

 

[Tiny Spark]

Yeah new ones are pretty crap.
I found a stash of old ones the other day in a drawer though so I have been using them the last few weeks.
You can even get a spanner on em!!
Why dont they make em like they used to

 

[davesparks]

If I'm in a fix and have to use a banjo for whatever reason then I tend to double them up as they just don't look thick enough.

 

[benji]

Got to say an earth tag does have a greater contact area than a gland /l.nut, the larger size tags 50-63-75 are rated at 10.40ka fault current so when the cables armour can exceed that value and there is a possibility that it might have to a gland with an integral earth boss should be used ,so the idea that the gland / termination doesn,t need earthing and that the trunking / gland plate is acceptable needs to be checked out.Can,t find the ka rating of glands though.

 

[Knobhead]

Got to say an earth tag does have a greater contact area than a gland /l.nut, the larger size tags 50-63-75 are rated at 10.40ka fault current so when the cables armour can exceed that value and there is a possibility that it might have to a gland with an integral earth boss should be used ,so the idea that the gland / termination doesn,t need earthing and that the trunking / gland plate is acceptable needs to be checked out.Can,t find the ka rating of glands though.

So where is that going to help when the fault level at the transformer is liable to be around 25KA?

 

[Tiny Spark]

So where is that going to help when the fault level at the transformer is liable to be around 25KA?

Dont think he is talking about the Tranny now Tony.

 

[tidyboiler]

Buffalo blood and urine concentrates have two of the colours covered, it's the blue we have trouble with.

Don't you have a visitor from the Royal family over there? maybe you could get them to open a vein....... there you go... blue!

 

[Knobhead]

Dont think he is talking about the Tranny now Tony.

I know he wasn’t referring to the transformer.

I’m having a go at the way the thread has left an important topic that it is clear few understand for a load of unrelated pointless drivel.

 

[benji]

Just cable installations in general, it would be wrong to assume that a piece of trunking or gland plate on its own is ok to gland into without checking possible fault currents

 

[shanky887614]

Just cable installations in general, it would be wrong to assume that a piece of trunking or gland plate on its own is ok to gland into without checking possible fault currents

depends on the scenario.

why would you need a banjo on cat5 swa?

 

[benji]

I was refering to power cables but to answer your question possibly if it was glanded into a plastic enclosure

 

[shanky887614]

I was refering to power cables but to answer your question possibly if it was glanded into a plastic enclosure

for a data cable? the swa is just for mechanical protection in this case as it would be for data rather than power

 

[Knobhead]

August Rush - Dueling Guitars - YouTube

 

[benji]

August Rush always meant to see that ,thank you will have to check itunes

 

[Knobhead]

Ooopps, that'll teach me to look at what I post, it should have been this

Dueling Banjos

 

[Knobhead]

Think the argument is 50/50 about the clamping the cables down although it gives that professional finish but must agree with everyone else ... heat shrink a must - tape is rough and you rely on the tape gum for the life span of the equipment although it poses not real safety risk a few yrs down the line your tape could be pealing and giving your work a poor reputation to anyone that follows you. Having said that if all your been pulled for is lack of heat shrink and a debatable lack of fixing then I wouldn't fret too much and take the advice on board.

Just spotted this post DW.

The jury has returned with a verdict. Have a look elsewhere for a topic on transformer tails. In particular the bit about magnetic reaction under fault conditions. It’s not a case of they look better, it’s a matter of safety.

 

[HandySparks]

Just spotted this post DW.

The jury has returned with a verdict. Have a look elsewhere for a topic on transformer tails. In particular the bit about magnetic reaction under fault conditions. It’s not a case of they look better, it’s a matter of safety.

Cleated cables on ladder under fault conditions:
https://www.youtube.com/watch?v=YZiTmk7cDrM

 

[Silly Sausage]

https://www.youtube.com/watch?v=HmnrJa7Zk0A

5 minutes onwards to see what happens with weak cleating!

 

[Knobhead]

Cheers HS and Archy, both of those clips prove the point rather well.

 

[Maddison]

not the kind of thing you want to get wrong...

 

[Knobhead]

One poor sod got chopped in half by trench cover plates being thrown in the air.

That was back in the 80’s, a couple of months before I started re-cabling a substation. For some strange reason we had a bit of a rethink about the job. I’ve had a bee in my bonnet ever since.

OK you can use the reasoning, what are the chances of it happening?
Quite high, the substation above one of the mates let a ¼” chequer plate drop in to the trench. There was 28x500mm cleated to the sides, fortunately it only skinned the outer serving off a few of them. Had it gone through the insulation there would have been 4x1000KVA 11/.433KV transformers feeding the fault.
Can’t say I was too happy, I had to repair the cables. A week after we’d put them in.

 

[Guest112]

Tony, in the op pictures, do you think that not cleating the spaced cable vertical drops could be dangerous under fault conditions in this situation? The reason I ask is because they are't run in trifoils but are rather entering up vertically spaced apart?

 

[Knobhead]

The distance between them is about the only saving grace.

Depending on how they are fastened in the trench has a bearing on the drops from the terminal box. If they can move in the trench then damage will be done to the terminals.

I would put them in single cleats anyway.

 

[Tiny Spark]

Damn never seen anything like that!
Gives a good appreciation of why though!!

 

[Knobhead]

Makes banjos seem insignificant doesn’t it.

 

[Tiny Spark]

Well I knew big cables were rated for big fault current but I never realised they could react like that!!
Though yes It would make many things seem pointless and insignificant.
Its funny I have been in a few subs and allways given the stuff a wide birth when I didnt have to be near it but think ile have to stay clear of the ladder racks to now LOL

 

[Silly Sausage]

Makes banjos seem insignificant doesn’t it.

It shows the power of an invisible magnetic field. Awesome!
One reason why electricity is such a fascinating subject.