No Banjo On Swa - C3?

[Stoneman]

Hi,

Did an EICR recently - one of the 3P subs used a 35mm 4C SWA.

There was no banjo at either end - Zs was fine (testing with only cable CPC/armourings)

Can't find an actual reg saying a banjo is needed...opinions on the classification?

Cheers.

 

[Jono Pashley]

Is the armouring effectively earthed via a metal gland plate?

 

[Murdoch]

Hum, I thought that one had to be at one end or the other

 

[kerching]

Is the gland plate reliably connected to the main body of the board, which in turn should be reliably connected to its earth terminal by "metal to metal joints of negligible impedance"

Some boards have a very poor connection between gland plate and body

Just warning

 

[Sidewinder]

The armour must be reliably earthed at supply end.

If you have a gland plate, then, you must ensure that the gland plate is an adequate earth path.

First port of call will be MI's, which will almost certainly say no.

So you need a banjo supply end, with a fly lead probably.

Now, as this is a sub-main it seems, the earth is being carried by the swa?

Or, is the 4th core an earth or a Neutral?

I'm guessing a N, thus earth is the SWA.

So, you now need a reliable method of transferring the earth path from the SWA to the board earth terminal.

So this may again require a banjo, and a fly lead, if you have a gland plate especially.

A low resistance ohm meter is not really suitable for testing such low impedance connections, though it is all most of us have.

A good high current loop test is better, but not perfect.

So, probably banjo & fly lead at both ends.

Now the code will be at least a C3, if you can't prove a low enough Zsdb then you might need to go to a C2.

However, I'm not there, you are.

 

[NozSpark]

Unless they've used a Pirranha nut (or similar)

 

[Sidewinder]

Yes Noz, quite, I did think of adding that, but, I thought it might have been too much of a revelation!

I carry 20, 25, 32 & 40mm Piranha nuts on the van.  :innocent

Just gloating...

 

[kerching]

Yes Noz, quite, I did think of adding that, but, I thought it might have been too much of a revelation!

I carry 20, 25, 32 & 40mm Piranha nuts on the van.  :innocent

Just gloating...

You have beaten me by "1"

I only go up to 32 piranhas

Just lacking in van stock, sort of

 

[Stoneman]

Yes, armourings used as cpc - Zs at sub board is good. This shows good mechanical contact at both ends of the SWA to chassis.

With this in mind, I'll make a C3 observation due to no banjo's - I'm sure you can understand my original question when I'm quizzed about the comment?

Btw, I tend to only fit a banjo to one end of an SWA... Probably gonna get shot down now!?

Brilliant, cheers.

 

[Sidewinder]

Yes, armourings used as cpc - Zs at sub board is good. This shows good mechanical contact at both ends of the SWA to chassis.

With this in mind, I'll make a C3 observation due to no banjo's - I'm sure you can understand my original question when I'm quizzed about the comment?

Btw, I tend to only fit a banjo to one end of an SWA... Probably gonna get shot down now!?

Brilliant, cheers.

Can you see where I am coming from with my post?

If so then fine, just banjo both ends from now on, not going to shoot you, hanging, drawing and quartering is much more interesting!

It also occupies more time, which is good if you are on an hourly rate!

 

[Evans Electric]

Stoneman  ....can you stand still while I take aim

We were informed many years ago , when banjoes started to appear with glands , that someone had decreed that the surface area of the gland was not large enough to carry fault currents. 

Original MI 's  were to fit banjo  (both ends)  file paint off gland plate , drill & bolt banjo to plate .   An adequate earth strap from the plate to the earth bar should be fitted.     Circa  1066 .

Un-officially ...we added our own addendum ..........(   you will see most sparks of my generation doing this) ......   all locknuts ,when tightened as far as possible with the grips ,  will be finished off with the application a hammer & suitably sized chisel .

 

[kerching]

I always used a big nail punch as it did not chew up the flats on the nut

Someone somewhere will be telling us we need a torque wrench next!

Just waiting

 

[Manator]

You need a torque wrench!!

 

[kerching]

I have a 1000V VDE rated one, if that counts?

 

[kerching]

My wrist clicks...does that count?

 

[Andy™]

depends if its within calibration... doesnt your corner shop do calibrations?

 

[kerching]

depends if its within calibration... doesnt your corner shop do calibrations?

Corner shop can provide calibrated equipment BUT I think,it is done elsewhere.

I am OK though as Rachel Riley provides a traceable wrist standard on a regular basis

 

[poni]

how do you get hammer & chisel calibrated to a set torque?

 

[Tradecerts]

I would have gone with a C3 but you seem pretty well covered with the answers already given