Ground wire size

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Grouch1980

Grouch1980

Senior Member
Location
New York, NY
Hi,
In NYC, let's say i have 2 service switches that tap off from a Service End Box. on the load side of each switch, you would size the grounding conductor based on the fuse size of each switch (and then upsize for any possible voltage drop). however, how do you size the ground wire between the Service End Box and each switch (line side of the switch)?
 
Your terminology is confusing. Service end Box? Are you talking about an equipment grounding conductor or a grounding electrode conductor. My guess is you are asking about the grounding electrode conductor however you don't upsize the grounding electrode conductor for vd. Please clarify
 
Ok looks like you want the equipment grounding conductor. but I am still confused on the last part-- do you mean the grounded conductor-neutral
 
Grouch1980 said:
Hi,
In NYC, let's say i have 2 service switches that tap off from a Service End Box:

1) on the load side of each switch, you would size the grounding conductor based on the fuse size of each switch (and then upsize for any possible voltage drop).

2)how do you size the ground wire between the Service End Box and each switch (line side of the switch)?
Click to expand...

1) You would have an EGC on the load side of the OCPD so you would use T250.122 based on the size of the OCPD.

2) There is no "ground wire" between the service switch and the end line box. Every metal component ahead of the service disconnect is bonded directly to the neutral.
 
That's right! Thanks. I kind of realized that after i posted it lol. so if you have any ground fault current, it travels through all the metal components / EGC's throughout the system back to the main bonding jumper in the service switch, to the neutral in the service switch (via the main bonding jumper), and then travels through the neutral back to the end line box and back to the utility... did i say that right? so there is no need for that "ground wire" (or any type of grounding connection) between the service switch and end line box.
 
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We run into terminology issues with 'grounding' all the time...please look up the definition of ground.
"What color is it and what does it do"? Mike Holt
"We have met the enemy and it is us" Pogo
 
tom baker said:
We run into terminology issues with 'grounding' all the time...please look up the definition of ground.
"What color is it and what does it do"? Mike Holt
"We have met the enemy and it is us" Pogo
Click to expand...

i don't know... I said 'grounding'... not grounded. i'm talking about the green grounding system / metal enclosures. not the grounded / neutral system.
 
Hey guys,
Just a follow-up to my original post... I spoke to a colleague of mine who said that, if (just hypothetically speaking) you decide to use PVC conduits to connect the line side of the service switches back to the end line box, you still need to route an EGC / grounding wire along with your phase legs and neutral inside the PVC conduits. My question is, why would this grounding wire be needed? Wouldn't the main bonding jumper in the service switch take all ground faults back to the neutral wire?
 
Grouch1980 said:
Hey guys,
Just a follow-up to my original post... I spoke to a colleague of mine who said that, if (just hypothetically speaking) you decide to use PVC conduits to connect the line side of the service switches back to the end line box, you still need to route an EGC / grounding wire along with your phase legs and neutral inside the PVC conduits. My question is, why would this grounding wire be needed? Wouldn't the main bonding jumper in the service switch take all ground faults back to the neutral wire?
Click to expand...

You're colleague is incorrect and yes you're correct the MBJ will direct the fault current back to the neutral. Using PVC or metallic
raceways has no significance because as stated earlier there are no EGC's on the line side of the service disconnect.
 
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