Spot The Fault

[Badger]

i reckon thats at least 6mm armoured

 

[Sidewinder]

That's a new one to me as long as one end is earthed it does not matter you are not using the SWA as a cpc

Do an FMEA on it and you'll see why.

Also look at the physical earth loop paths and include these in your FMEA, then you will understand.

 

[kerching]

should get some of these

http://www.ebay.co.uk/itm/Mens-Dickies-WP1500-Padded-Work-Rain-Suit-Waterproof-Motorcycle-Fishing-Overalls-/151476255039?pt=LH_DefaultDomain_3&var=&hash=item2344b0393f

Got one!

I look like a F fat Jelly Baby...but a warm one!

 

[Adrian]

I understand it is not good practice but to make a statement it is dangerous and not compliant is not true

 

[Andy™]

I understand it is not good practice but to make a statement it is dangerous and not compliant is not true

if you have a long run that is borderline Zs at the end, then you have a fault, chances are the Zs working back will be too high. not exactly compliant, is it?

Got one!

I look like a F fat Jelly Baby...but a warm one!

who cares what you look like with them, as long as your warm. a little too warm at times though

 

[kerching]

I sweat like Cliff Richard when wearing it....luckily not needed very often!

Last time was up,at the old Shotton Colliery site. F Freezing or what??

Even the local,totty Were wearing extra glitter and fake tan to stave off the icicles

 

[Adrian]

That would have to be a long run to be higher than 1667ohms

 

[Sidewinder]

That would have to be a long run to be higher than 1667ohms

Not quite the issue.

Have a look at the potential failure modes, why the SWA is there and what it is to prevent.

 

[Andy™]

That would have to be a long run to be higher than 1667ohms

SWA often doesnt have RCD protection...

 

[Steve3948]

SWA often doesnt have RCD protection...

However this install does  :innocent

 

[Andy™]

However this install does  :innocent

not much use when it it doesnt work though...

 

[Adrian]

and by earthing the swa at the supply end on this tt installation would cause the mcb to trip ? (don't think so)

the swa is only there for mechanical protection and as long as the earth fault loop is not above 1667 ohms then the rcd would trip as I have previously said it is not against the regs and is not dangerous. If it is can someone please tell me the reg as I seem to be missing out on a lot of work as I have come across this loads of times   

 

[ProDave]

and by earthing the swa at the supply end on this tt installation would cause the mcb to trip ? (don't think so)

the swa is only there for mechanical protection and as long as the earth fault loop is not above 1667 ohms then the rcd would trip as I have previously said it is not against the regs and is not dangerous. If it is can someone please tell me the reg as I seem to be missing out on a lot of work as I have come across this loads of times   

Some people just don't see reason and will continue doing things wrong no matter how clearly you explain it to them.

see post #15

 

[Adrian]

Prodave please im begging you, show me the reg 

 

[Nicky Tesla]

Do an FMEA on it and you'll see why.

Also look at the physical earth loop paths and include these in your FMEA, then you will understand.

earth connected at DB................earth connection at banjo fails  armour can become live after a fault

earth connected at appliance..............earth connection fails armour can become live after a fault

No different unless armour connected at both ends

is this what you mean ?  if not let the cat out of the bag and stop with all the cryptic clues and moods.

 

[Sidewinder]

earth connected at DB................earth connection at banjo fails  armour can become live after a fault

earth connected at appliance..............earth connection fails armour can become live after a fault

No different unless armour connected at both ends

is this what you mean ?  if not let the cat out of the bag and stop with all the cryptic clues and moods.

Just got in from work (a different job to this one).

No moods from me.

Obviously I am the only one who has been to site and seen the install, so I don't expect the detail that perhaps you think I did.

If you read my OP, I did not say that this was to score points or such like.

Be back later, Mrs SW has just dished me up some food.

 

[Evans Electric]

There not a Reg for everything we do ...theres Codes of Practice  etc .  

Theres a few things that are not easily found , or that some sparks have never heard of . 

Slotting the holes in metal plates with single core conductors passing through is one that comes to mind.

Exporting PME earths is another .

Finding armour banjos on the INSIDE of an enclosure ..when years ago  we were instructed that the surface area of the gland was deemed not to be large enough so the banjo increases the surface area ......but until recently I'd never seen them on the inside under the locknuts. 

Just stirring .

 

[apprentice87]

I shall comment on this in two parts, the first one for the information of dummies....

Earthing of the armour.....

Now then; The armour of the cable, even if it is NOT used as a CPC for the associated circuit HAS to be earthed AT THE SUPPLY END.

Doubt me, oh well, i am only a stupid welder, no electrical quals at all. BUT, even i have the sense to know that the armour of a cable, even if it is ONLY there to provide mechanical protection, HAS to be earthed at the supply end to the main earth terminal, [by whatever means] for various reasons...

First off,

You cannot "mix and match" earthing arrangements. You cannot have simultaneously accessable parts connected to different earthing systems. 411.3.1.1

If you run a cable off to another installation, [that has SEPARATE earthing arrangements,] you would HAVE to earth the cable CPC at the end with the "associated protective device" [the supply end] and insulate it from the earthing arrangements in the second installation. 542.1.8

Secondly,

If mechanical protection of a cable is REQUIRED, [as in the case of cables not buried deep enough in a wall or whatever] then it is ALSO [the mechanical protection] required to be earthed, it also HAS to be connected to the earthing terminal of the associated supply as the mechanical protection is part of the installation that COULD become live in the event of a fault, so therefore it is an "exposed conductive part" and HAS  therefore, to be connected to the SAME earthing system. 411.3.1.1

Finally, Ok, say the cable DID NOT NEED mechanical protection, you just used SWA "cos we had some" The armour could well be seen, and the glands at the end DEFINITELY are, EXPOSED CONDUCTIVE PARTS, and therefore, need to be connected to the main earth terminal of the installation that contains the associated protective device.  Once again, 411.3.1.1

john..

 

[ProDave]

Prodave please im begging you, show me the reg 

Do you ONLY do something because the BYB tells you to, or do you sometimes do something because it's good engineering practice?

 

[Sidewinder]

The SWA must be earthed mechanical protection though, not just mechanical protection.

On this site, there is no resident spark.

The site operators will reset breakers if they trip.

If the cable is cut clean through, which it is likely to be as it is laying on the ground, as per post #15.

Yes it does have markers but...

Now the cutting of the cable would trip the RCD, if it works, which in this case it did not, however, that is irrelevant.

The RCD would then be reset by site staff.

Now if there is a clean cut through the 3 cores and the SWA, and the live core is in contact with the SWA on the supply side, then the SWA will become live, and you will be relying on the RCD to provide primary protection, you should not do that.

I'll dig out a reg as soon as I can.