Earthing a mobile lighting rig

[Bobster]

Even one deep rod as described above could possibly suffice if this is a for a very temporary installation...

Probably there for a week tops.

If your talking about a quarry situation, then your, or the workers employers have a duty to ensure safety on the site. As Tony has stated M&Q rules apply which are by far, stronger in the legal arena than BS7671. In fact as i recall, quarries have their own set of rules and regulations...

This is why I was asking advice, because of the ground material I wouldn't have thaught a normal earth rod would provided a good enough earth.

 

[La Poste]

A quarry? They have some fun toys.

Get the owners to dill a 50mm shot hole by each lighting position about 10m deep. They won’t take long to drill. Put the rods in and fill with bentonite or urea. Urea is cheaper but pongs when you add water to it. It also acts faster than bentonite.
The generator, one spike at two diagonal corners. Make sure the neutral is properly earthed.

Would the supply from the Genny to the lights be RCD protected?
What sort of circuit breaker would be used in the event of an earth fault?
Just curious.
Thanks.

 

[Bobster]

Rcd then through (off the top of my head) a 32A breaker. Feeding 4 x 1000w lamps.

 

[Knobhead]

You are under M&Q reg’s. End of.

Sorry but that’s life! BS 7671 doesn’t come in to it!

 

[Engineer54]

Rcd then through (off the top of my head) a 32A breaker. Feeding 4 x 1000w lamps.

Why wouldn't you get the quarry company to drill a shot bore for your earth rod(s) as Tony suggested, they must be drilling the things every day anyway!! Not as if the rods, couplers, etc, are going to be wasted, as you just pull the things out of the Bentonite soil enhancer when your done with the temporary lighting installation...

You could well be surprised by the value you obtain, going down 10 metres as Tony suggested. Limestone can be full of fissure's that hold ground water and dissolved conductive sulphates and chlorides etc .. lol!!

 

[Bobster]

Eng 54 - the company wouldn't spend money on an earth mat as suggested before. The drilling rigs moving round for Friday .

 

[Engineer54]

Eng 54 - the company wouldn't spend money on an earth mat as suggested before. The drilling rigs moving round for Friday .

Errr!! One/single earth rod position does not constitute an earth mat, not under any stretch of the imagination.. lol!!!

 

[Bobster]

Think there's been a miss understanding.

The company wouldn't fund an earth mat. Not for something so temporary.

Im going to instead put two earth rods in as per Tony's suggestion. Test and see if there suitable.

 

[Knobhead]

How far away is the 3.3KV header main? You could earth to that if the cable can be protected.

 

[Engineer54]

Think there's been a miss understanding.

The company wouldn't fund an earth mat. Not for something so temporary.

Im going to instead put two earth rods in as per Tony's suggestion. Test and see if there suitable.

Errr.... isn't that what was suggested to you in the first place?? Who has mentioned anything about Earth Mats?? Your not going to bang earth rods into limestone, it's going to need drilling mate, which was also suggested to you early on in this thread!!! And if drilled and installed with a soil conditioner (say Bentonite), the rods are fully retrievable after use, you just pull them up out of the bore holes!!!

 

[Bobster]

Post 6 an earth mat was suggested and I said the post after I couldn't do that.

Im not sure where you got that I dismissed Tony's idea at all? I knew I couldn't just drive earth rods into limestone hence the thread.

 

[Engineer54]

Eng 54 - the company wouldn't spend money on an earth mat as suggested before. The drilling rigs moving round for Friday .

Sorry, i was meaning that i hadn't mentioned anything about an earth mat!! lol!!

 

[Bobster]

No worries think we had a wire crossed.