Tap connection

[DARUSA]

I was on a new job yesterday and saw something that was not set correctly to me.My boos says it was fine but I'm a little confuse.
The tap for the 400amps combo was made on the 2000 DS lugs. I mean the 500 kcmil wire was connected directly from the 2000 DS lugs. and from the same lugs is 5sets of 600 kcmil wire running to the wire-way were there is the taps connections for the other 800 amps services. My question is! The wire for the 400 amps service can be connected on the 2000 amps DS lugs? or should be the tap made on the 600kcmil sets of wire?

 

[LarryFine]

Doesn't the 10' tap rule apply here? If so, and the conductprs have their own lugs/holes, why not?

If you had the right lugs, I would think every feeder could land directly on the main.

 

[DARUSA]

Doesn't the 10' tap rule apply here? If so, and the conductprs have their own lugs/holes, why not?

If you had the right lugs, I would think every feeder could land directly on the main.

What you says is that everery set can come off the DS lugs . 1 set of 500 (400amps office),2 sets of 500kcmil for each 800 service all connected to the lugs but what about if one of the service is 200amps the 3/0 wire can be connected to the lugs too?

 

[ohmhead]

Well its fine one thing to remember is when you tap a sevice in your gutter you must tap all the phases not just one or two .


Meaning if you had a 400 amp added service tapped on to a 1200 amp main all the feeders in that gutter feeding each other meter or disconnect must be tapped to each and every phase or neutral in that gutter all of them .


So each parallel main feeder is connected to your 4 wire tapped 3 phase connection you made.

Ive seen people just tap one phase here and one phase there this will overload that single phased hot conductor of the paralled group and create a unbalanced hot thats why your boss said to do it that way .


Your last question is YES thats protected by its own disconnect so its fine .

 

[iwire]

What you says is that every set can come off the DS lugs.

Yes.

1 set of 500 (400amps office),2 sets of 500kcmil for each 800 service all connected to the lugs

Yes.

but what about if one of the service is 200amps the 3/0 wire can be connected to the lugs too?

Yes, if the taps are 10' or less in length.

If the tap is longer than 10' the 25' tap rule 240.21(B)(1) requires the tap condutors to have a rating of at least 1/3 the rating of the feeder.

2000/3= 667 amps so 3/0 would be to small.

 

[DARUSA]

Yes.



Yes.



Yes, if the taps are 10' or less in length.

If the tap is longer than 10' the 25' tap rule 240.21(B)(1) requires the tap condutors to have a rating of at least 1/3 the rating of the feeder.Both sets come from the 400amps DS lugs.

2000/3= 667 amps so 3/0 would be to small.

OK! what about if I have 400 amps DS and 2 separate panel in different location.Can I connect my two sets of 3/0 and run one to each panel in separate raceways to different locations?.Each 200 amp panel will have a Main breaker.

 

[iwire]

OK! what about if I have 400 amps DS and 2 separate panel in different location.Can I connect my two sets of 3/0 and run one to each panel in separate raceways to different locations?.Each 200 amp panel will have a Main breaker.

Yes, within 25' of conductor length, which if complied with keeps things pretty close together.

 

[DARUSA]

Ok is clear now Thanks everybody !!!

 

[ohmhead]

Well heres kinda the best gutter tap box ever stainless encloser & silver plated buss and you cant make a mistake .

 

[infinity]

Since you cannot go up to the next largest size OCPD on tap conductors your one set of 500' is not good for 400 amps and the same would be true for two sets of 500's on the 800 amp. 240.21(B).

 

[iwire]

Since you cannot go up to the next largest size OCPD on tap conductors your one set of 500' is not good for 400 amps and the same would be true for two sets of 500's on the 800 amp. 240.21(B).

That is a good point, his drawing shows 600s but his text says 500s.

 

[Smart $]

That is a good point, his drawing shows 600s but his text says 500s.

Sounds like a botched design with some field adjustment.

Could have just run 2 sets of 600s to each of the 800A disconnects and one set of 600s to the 400A disconnect, thereby eliminating all the wire taps...

 

[DARUSA]

500 kcmil !! Next side up not apply

500 kcmil !! Next side up not apply

Sounds like a botched design with some field adjustment.

Could have just run 2 sets of 600s to each of the 800A disconnects and one set of 600s to the 400A disconnect, thereby eliminating all the wire taps...

Yes you right.,In my diagram I sized the service feeder based on the 2000 amps OP (5 sets of 600) later I size the sts based on each OP an I don't make attention on the tap rules!! But my question was based on were I can make the tap if I can make one directlly on the lugs ( 2000 amps DS lugs) or I have to make all the taps togheter inside of the wire way )