swa to gland plate, earth lead from banjo required?

[jim23]

hi guys, this isnt a DIY question but wanted to know what others thought as there seems to be some good sparks on here.

situation.....

company i work for had NICEIC contractors replace a 300mm 4 core swa cable(3phase Neutral, armour as earth). the cable was from a suppliers LV fuse cabinet in their substation. It runs about 10 metres into our main switch (a tpn switchfuse).Because a compatible spreader box wouldnt fit the space below the switchfuse they used a standard sheet steel enclosure. This enclosure has a removable gland plate into which they have terminated the swa gland. the gland plate has 12 small self taping screws holding it in place (not all are fitted correctly as the plate is bent slightly (tail wagging the dog and all that).

the banjo is on but not bolted through so obviously no earth tail is taken to the switchfuse or our MET. The Zs/Ze measurment is good (0.01 for what it is worth) but im concerned about the lack of earth tail from banjo. i was always taught with gland plates to take the earth from the banjo. they also havent removed any paint from around the gland or the banjo. system is TNS. basically im not happy with the works done.


im checking tomorrow to see if they issued a cert which they said they were going to. i have a feeling they will try and claim its our responsibility to do the earth or just claim the work is satisfactory.

going to have a look at regs later see which ones i think it contrevienes but i think maybe 543-02-07 to start with.

opinions please.

 

[Spark123]

For what it is worth we have always fitted the banjo to the outside of the metal plate, cleaned the paint off, brass bolt through, crimped lug on the inside and the appropriate sized cable from there to the correct earth terminal etc. Otherwise, how can you say the connection is sound?

 

[Lectrician]

If they have altered the switch fuse with an enclosure used as a spreader box, then the BS of the switch box/spreader box is null and void. You can then not rely on any of the case as the means of earthing in my opinion.

I would always banjo cables this size anyway, and to be honest, if it is the main feeder (or even if it was just a submain), this cable should really be supplimented with a single earth too - and with a 10m length, there is little excuse not to.

 

[ban-all-sheds]

hi guys, this isnt a DIY question but wanted to know what others thought as there seems to be some good sparks on here.

While you wait for one*, I'll give you a DIY answer - I agree fully with you, there should be an earth connected to the banjo etc.

300mm 4 core swa cable(3phase Neutral, armour as earth).

Assuming a gland no bigger than 75mm you can get piranha nuts in the correct size. Bit of a b***er to retrofit though..

The Zs/Ze measurment is good (0.01 for what it is worth) but im concerned about the lack of earth tail from banjo.

Unless I've misunderstood what's going on, your earth path relies on those self-tappers?

*Doh - I see one turned up after I started my reply...

 

[jim23]

all the points you make guys are correct and i agree with them. the job was done a few months back now and the contractors have been paid. ive also checked and they didnt issue a certificate to us for the work, im presuming they should have but not 100% sure because of the cable being the link from suppliers equipment to our main switch.

ban, you are correct that the self tappers are the earth path, wouldnt fancy them standing up to fault current tbh!

 

[ban-all-sheds]

Tell your manager and the location manager/safety officer that your company is now in violation of the EAWR.....

 

[333rocky333]

This proberly dont apply in your case but

With APEA quidance which is for petrol stations including the non hazourdous areas

With swa, an earth tagged washer (banjo) needs to be fitted on the outside beneath the gland , and a cable lugged on the inside , using a non corrosive nut and bolt,

This cable then connects to the earth bar or terminal in the enclosure

The cable must be same size as the phase conducter and no smaller than 2.5mm
This is in addition to any protective conducter within the cable

I would also say it is good practice in ANY situation
(Though In your case the earth size may not need to be that big)