Taps

[hhsting]

Attached sketch shows 400A fused service disconnect feeding a trough which is tapped to tap conductors to 225A ATS and to fused disconnect to RTU. Load side of ATS is then fed thru another trough which is then tapped again to panelboard and to fused disconnect.

Questions are following:
1. Tap conductors to ATS does code require 225A breaker between trough and ATS? If yes then which code section.

2. Looks like tap of a tap but not sure since ATS comes in between. Is this tap of a tap? If yes then which section of 240.21 is violated?

3. Would it be tap of a tap if 225A breaker is provided between trough and 225A ATS

4. Is their any other code violation being done here?


Thanks for your input

 

[jap]

I'd be curious how the RTU Fused disconnect is tapped to the parallel conductors,
and
If the Transfer Switch incorporates any type of OCPD.

JAP>

 

[kwired]

Attached sketch shows 400A fused service disconnect feeding a trough which is tapped to tap conductors to 225A ATS and to fused disconnect to RTU. Load side of ATS is then fed thru another trough which is then tapped again to panelboard and to fused disconnect.

Questions are following:
1. Tap conductors to ATS does code require 225A breaker between trough and ATS? If yes then which code section.

2. Looks like tap of a tap but not sure since ATS comes in between. Is this tap of a tap? If yes then which section of 240.21 is violated?

3. Would it be tap of a tap if 225A breaker is provided between trough and 225A ATS

4. Is their any other code violation being done here?


Thanks for your input

if using 10 foot tap rule, you may be able to have the 225 amp TS in the tap, but pretty certain you can not split the tap afterward like is shown. (tapping a tap).

If using the 25 foot tap rule you must terminate the tap at an overcurrent device.

 

[Johnhall30]

This may be a violation of 240.21(B)(1)(2) -The tap conductors do not extend beyond the switchboard, switchgear, panelboard, disconnecting means, or control devices they supply.

Would the ATS be considered a control device?

 

[hhsting]

I am not sure how the taps are made to fused disconnect to RTU. The RTU disconnect is fused at 40 amps. So by #8 phase conductors tapped from 2 sets of 3/0AWG. Not sure where would you be getting from this??

Their is no OCPD in transfer switch. The trough to the ATS/RTU fused disconnect and transfer switch itself are within ten feet of each other. The question is if ten feet allows it without OCPD between the trough and transfer switch then what is protecting the ATS since upstream breaker is 400A?

 

[texie]

An ATS not only requires an OCPD, the type, size and sometimes brand is specifically spelled out on the ATS.

 

[hhsting]

An ATS not only requires an OCPD, the type, size and sometimes brand is specifically spelled out on the ATS.

What is the code section that requires ATS to be protected from OCPD upstream?

 

[jap]

I am not sure how the taps are made to fused disconnect to RTU. The RTU disconnect is fused at 40 amps. So by #8 phase conductors tapped from 2 sets of 3/0AWG. Not sure where would you be getting from this??

Their is no OCPD in transfer switch. The trough to the ATS/RTU fused disconnect and transfer switch itself are within ten feet of each other. The question is if ten feet allows it without OCPD between the trough and transfer switch then what is protecting the ATS since upstream breaker is 400A?

Just saying you would need to be sure that the single #8's are tapped to BOTH parallel conductors of each ungrounded conductors.
Some installers are guilty of only tapping onto one of them.

I've never been a big fan of connecting anything to a feeder that's above it's rating such as the 225a Xfr switch being connected to a 400a rated feeder in the sketch.

Regardless of whether a 10' tap rule allows it or not.

JAP>

 

[texie]

What is the code section that requires ATS to be protected from OCPD upstream?

Here is good article on this: https://www.csemag.com/articles/automatic-transfer-switch-protection/

 

[GoldDigger]

Once a tap conductor has reached OCPD appropriate to its ampacity, the output of the OCPD is no longer a tap and can itself be tapped.

 

[jap]

Once a tap conductor has reached OCPD appropriate to its ampacity, the output of the OCPD is no longer a tap and can itself be tapped.

That's the thing.
Without knowing the wire sizing at each location, it's hard to tell if this is even a tap situation to begin with.


JAP>

 

[hhsting]

That's the thing.
Without knowing the wire sizing at each location, it's hard to tell if this is even a tap situation to begin with.


JAP>

No no verfied twice these are taps not splice. Conductors are not 2 sets of 3/0 awg to Rtu disconnect, ATS and ATS load side trough.

 

[david luchini]

No no verfied twice these are taps not splice. Conductors are not 2 sets of 3/0 awg to Rtu disconnect, ATS and ATS load side trough.

Then you need an OCPD between the tap and the ATS

 

[kwired]

That's the thing.
Without knowing the wire sizing at each location, it's hard to tell if this is even a tap situation to begin with.


JAP>

It appears we have 8 AWG conductors with 400 amps overcurrent protection ahead of them, sounds like feeder tap rules need to be applied to them to me to keep it with 400 amps protection on supply side. Whether or not the ATS can be located within the tap is a valid question. 25 foot tap rule I don't think so. 10 foot tap rule or even outdoor tap of unlimited length, maybe, but will also need to consider listing of the ATS I would think.

 

[jap]

All I was getting at was the wire size is not shown beyond the first gutter.
by the drawing, we could assume no reduction in wire size, and, therefore not a tap situation at all.

JAP>

 

[david luchini]

10 foot tap rule or even outdoor tap of unlimited length, maybe,

I don't see how either of those would be applicable.