connection between neutral and earthing at load side

[engmsm5]

Greetings,
if the distance between transformer and load is 200m . what is the difference between :
1-connection between neutral and earth at transformer.
2- connection between neutral and earth at load.

Physically: neutral is connected to earth in two cases.so, can i consider that the earthing system in two cases is TNS??

 

[engmsm5]

No one can answer me??!

 

[Oldbull]

Yes, but do they want to?

Yes, but do they want to?

Yes, I can answer you.

Its the distance! ! ! The wires' resistance adds resistance to the circuit that allows for higher available current before the breaker trips. Therefore, A bigger explosion and ball of fire when you screw up and get killed. It could be the differance between a small burn and third degree burns all over your body.
Remember , the "Ground makes the breaker trip!"

 

[GoldDigger]

And yet a 25 ohm ground will not make the breaker trip nearly as fast as 1 ohm wire will.
"Ground makes the breaker trip" is a totally false and misleading saying that needs to be shot down at every opportunity.
"A solid fault current path makes the breaker trip" does not have the same ring to it, but is correct!
Also higher resistance allowing higher fault current before trip is exactly backwards.
Higher resistance means lower current which means more time before the trip. That in turn can mean more total energy and damage.

Tapatalk!

 

[Smart $]

...
"A solid fault current path makes the breaker trip" does not have the same ring to it, but is correct!

Solid is a bit ambiguous. Low-resistance is better. NEC uses the term effective...

 

[iceworm]

Greetings,
if the distance between transformer and load is 200m . what is the difference between :
1-connection between neutral and earth at transformer.
2- connection between neutral and earth at load.

Physically: neutral is connected to earth in two cases.so, can i consider that the earthing system in two cases is TNS??

eng - Where is Ksa?

The only reason I ask is: The term "TNS" is not normally used in conjunction with the NEC.

ice

 

[Smart $]

eng - Where is Ksa?

Kingdom of Saudi Arabia (KSA)

 

[Besoeker]

eng - Where is Ksa?

The only reason I ask is: The term "TNS" is not normally used in conjunction with the NEC.

ice

BS7671 "The Regs" uses it.

 

[iceworm]

Greetings,
if the distance between transformer and load is 200m . what is the difference between :
1-connection between neutral and earth at transformer.
2- connection between neutral and earth at load.

Physically: neutral is connected to earth in two cases.so, can i consider that the earthing system in two cases is TNS??

Under the NEC one would normally have an Over Current Protection Device, say a fused disconnect, between the transformer and the load. In some cases, the OCPD can be a long ways from the transformer. Per the NEC, the NG bond can be either in the xfm, or in the OCPD, or anywhere in between.

However, in case 1, you would also need an equipment bonding conductor from the load N-G connection back to the transformer case. If you are trying to save 200m of wire - you can't. Either case requires the same amount of wire.

As others noted, the earthing connection doesn't trip anything> The equipment bonding conductors conduct the fault current that trip the OCP

As for your third question: Under the NEC, TNS doesn't come up. Best information I have on this is from two Schneider Electric papers. Do a Google search on "ect173", and "ect172"or look here
http://www2.schneider-electric.com/...ility-safety/low-voltage-minus-1kv/ect173.xml

and here
http://www2.schneider-electric.com/...ility-safety/low-voltage-minus-1kv/ect172.xml

ice

 

[kwired]

Greetings,
if the distance between transformer and load is 200m . what is the difference between :
1-connection between neutral and earth at transformer.
2- connection between neutral and earth at load.

Physically: neutral is connected to earth in two cases.so, can i consider that the earthing system in two cases is TNS??
View attachment 10131

The difference is dependent on the voltage drop on the conductor between the two locations, plus you have to factor in the parallel earth path, which is considered to have no resistance but the resistance to earth of the electrodes used will vary depending on many different conditions.

 

[GoldDigger]

As far as normal operating conditions go, there will be no difference between the two as long as the neutral to earth connection is made only at one end.
In one case (bond at transformer) there will be a voltage between neutral and earth at the load resulting from the voltage drop in the neutral wire.
When the bond is at the load end there will instead be a voltage between neutral and earth at the transformer end.
But in both cases the voltage across the load terminals will be exactly the same.
Under NEC rules, neither one of the two options would be legal. And if the 200m run belongs to the utility, and so is not subject to NEC rules, there would normally be an earth bond at both ends instead. That would then bring into play the parallel paths mentioned in the previous post.
In the case of a fault to an exposed metal surface on the equipment or to an effectively earthed surface, there would be differences between the two cases, but again, in the US neither case would be allowed as drawn.

Tapatalk!

 

[kwired]

I am starting to see that a possible further explanation of items drawn may make some differences in answers to the question.

Biggest question is what is the load, and why would you earth the current carrying neutral point at the load and not somewhere near the beginning of the distribution like at the source or the first disconnecting means, maybe both which is common if it is a utility source?