200a Disconnect and feeder Tap question

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mannyb

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Florida
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Electrician
1.I have a 225a breaker feeding a large condenser unit. Near the Unit there is a 200a non fused disconnect for servicing. Should the disonnect be larger or is the 200a disconnect suffcient for service disconnect at unit?

2. The feeder to Unit is damaged and needs new feeder run. The Location is an old parking garage at apartment complex. The feeder leads into a mech room that feeds another gutter where all the controls are located and then from that gutter feeds over to Condenser Units. I would like to run a new feeder to Unit first and use the undamaged or existing going back to Mech room to feed the equipment for the condenser units. My question to this problem Can I TAP off feeder to feed the equipment and controllers in mechanical room. Using the 10' tap rule i can install a fused disconnect then run existing undamaged feeder back to mechanical room. The distance between the Condesners and the mechanical room is about 100' inside mechanical room also located in parking garage. ALSO if I am able to TAP into the feeder. do i need a OCPD to condenser units from the point where i seperate the feeder one side condenser units and other controllers. Is there anything I should be concerned when deciding to do this? The feeder is damaged and because it ran underground inside parking garage we cant follow same feeder path. We basically need to take the conduit a little longer distance around for clearance.
 
I read some of the previous post on 200a NF disconnect with 225a breakers in line so i go that question answered and basically no

I am still need help with the feeder tap. I want to bring a new feeder 4/0 copper to a new 400a non fused disconnect for the 225a per condenser Unit MOCP specification because I cant use the 200a NF disconnect because the MCA us 194amps on unit. I want to run the 4/0 copper feed to a gutter near the condenser unit. I would then run feeder into the 400a NF disconnect and tap a 60a fused disconnect to supply the equipment in the mechanical room for control equipment for condenser. Does that look like a problem or a way i could do better?
 
mannyb said:
I read some of the previous post on 200a NF disconnect with 225a breakers in line so i go that question answered and basically no

I am still need help with the feeder tap. I want to bring a new feeder 4/0 copper to a new 400a non fused disconnect for the 225a per condenser Unit MOCP specification because I cant use the 200a NF disconnect because the MCA us 194amps on unit. I want to run the 4/0 copper feed to a gutter near the condenser unit. I would then run feeder into the 400a NF disconnect and tap a 60a fused disconnect to supply the equipment in the mechanical room for control equipment for condenser. Does that look like a problem or a way i could do better?
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Looks like the #4/0 (230A) will be slightly undersized when you add load for the Mechanical room.
 
Dale001289 said:
Looks like the #4/0 (230A) will be slightly undersized when you add load for the Mechanical room.
Click to expand...

The feeder to mechnical room supplies little to no power but Your right. What do you think about the feeder tap. once we determine usage in mechanical room. could I install a 60 disconnect with 10' then feed the mechanical room about 100' away?
 
mannyb said:
The feeder to mechnical room supplies little to no power but Your right. What do you think about the feeder tap. once we determine usage in mechanical room. could I install a 60 disconnect with 10' then feed the mechanical room about 100' away?
Click to expand...

Since you're not downsizing the cable it shouldn't be a problem. You may have trouble landing the #4/0 cable on 60A Disconnect lugs.
 
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mannyb said:
we plan on using polaris taps or quick taps for smaller wire to 60a disconnect.
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I am not clear on exactly what you are proposing but:
1. You cannot tap a tap, you have to land on OCPD first.
2. Unlike reducing conductors that were oversized for voltage drop, you cannot arbitrarily reduce conductor size below upstream ampacity except by invoking a tap rule.
I suspect your proposed connection to the 6OA disconnect may not be allowed

Sent from my XT1585 using Tapatalk
 
GoldDigger said:
I am not clear on exactly what you are proposing but:
1. You cannot tap a tap, you have to land on OCPD first.
2. Unlike reducing conductors that were oversized for voltage drop, you cannot arbitrarily reduce conductor size below upstream ampacity except by invoking a tap rule.
I suspect your proposed connection to the 6OA disconnect may not be allowed

Sent from my XT1585 using Tapatalk
Click to expand...

Could I run 250MCM CU to a gutter then tap (1) 400a switch with 225a fuses and (1) 30a disconnect for the misc that basically controlls Hvac controls. The whole lenght with hvac and controlls less than 150'.
 
mannyb said:
Could I run 250MCM CU to a gutter then tap (1) 400a switch with 225a fuses and (1) 30a disconnect for the misc that basically controlls Hvac controls. The whole lenght with hvac and controlls less than 150'.
Click to expand...
All that matters here is the length of the feeder tap. If you keep it to 10 feet or less you can have 10 AWG taps to a 30 amp disconnect off a 225 amp feeder.

Whether or not your 200 amp non fused switch would have been acceptable depends on some information that hasn't been provided, as well as max Hp rating of the non fused switch. However it also sounds like you don't have a branch circuit device for the HVAC unit but rather a feeder that ultimately will be supplying other "branch circuits".
 
kwired said:
All that matters here is the length of the feeder tap. If you keep it to 10 feet or less you can have 10 AWG taps to a 30 amp disconnect off a 225 amp feeder.

Whether or not your 200 amp non fused switch would have been acceptable depends on some information that hasn't been provided, as well as max Hp rating of the non fused switch. However it also sounds like you don't have a branch circuit device for the HVAC unit but rather a feeder that ultimately will be supplying other "branch circuits".
Click to expand...

can a 200a non fused be acceptable for service switch for HVAC. with a 225v breaker? what info is needed to determine that ?
 
mannyb said:
can a 200a non fused be acceptable for service switch for HVAC. with a 225v breaker? what info is needed to determine that ?
Click to expand...
Gets a little more complex with HVAC because they are not rated in HP.

I have many times put 30 amp non fused safety switch on 20 hp 480 volt motors with 60 amp breakers. The Safety switch (Square D heavy duty 600 volt) is rated for the HP, but if I were to use a fused switch would need to be a 60 amp switch, not so much because the switch rating itself but the fact that the 20 HP motor would need 40 amp fuses to assure starting without blowing the fuses.

The details are going to depend on the ratings of the switch you select. Chances are a "heavy duty" will be rated for this when a "standard duty" switch may not.
 
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