Elevator step up transformer and disconnect location

[Tainted]

Building is upgrading their elevator and the new elevator will require 480V 3 phase. Building has 208V 3 phase so we will need to step up transformer.

Power will be obtained in the basement electrical room. Does the transformer and primary and secondary disconnect for the transformer must be located in the elevator machine room or can they be located in the basement? There is no room to install the primary disconnect and transformer in the elevator machine room. The elevator machine room is located on the roof.

we only have room for the tertiary disconnect to be in the elevator machine room where all the elevator equipment is.

 

[Tainted]

So in other words, would it be ok to have the elevator transformer, primary, and secondary disconnect to be in the basement as long as we install a tertiary disconnect in the elevator machine room?

 

[infinity]

We install the step-up in the service room. It doesn't make much sense to run 208 up to the roof and then step it up to 480 due to VD on the 208.

 

[Tainted]

We install the step-up in the service room. It doesn't make much sense to run 208 up to the roof and then step it up to 480 due to VD on the 208.

I agree. I was under the impression that all elevator equipment including power transformers must be located in the elevator machine room, but looks my impression was not correct, thank you.

 

[infinity]

I agree. I was under the impression that all elevator equipment including power transformers must be located in the elevator machine room, but looks my impression was not correct, thank you.

For a large building we would install a big 208-480 substation in the service room and feed a switchboard to power the elevators

 

[electrofelon]

So in other words, would it be ok to have the elevator transformer, primary, and secondary disconnect to be in the basement as long as we install a tertiary disconnect in the elevator machine room?

You need to make sure you understand what the disconnect requirements are in the first place. For the primary side, here is the requirement but as you can see it's typically just academic that it be located within sight:

450.14 Disconnecting Means. Transformers, other than
Class 2 or Class 3 transformers, shall have a disconnecting
means located either in sight of the transformer or in a remote
location. Where located in a remote location, the disconnect‐
ing means shall be lockable in accordance with 110.25, and its
location shall be field marked on the transformer.

There is no requirement for a transformer "secondary disconnect", but you will need some ocpd to comply with 240.21(C) and possibly for transformers secondary protection 450.3(B) (sorry if I am nitpicking your terminology a little )

 

[Tainted]

You need to make sure you understand what the disconnect requirements are in the first place. For the primary side, here is the requirement but as you can see it's typically just academic that it be located within sight:

450.14 Disconnecting Means. Transformers, other than
Class 2 or Class 3 transformers, shall have a disconnecting
means located either in sight of the transformer or in a remote
location. Where located in a remote location, the disconnect‐
ing means shall be lockable in accordance with 110.25, and its
location shall be field marked on the transformer.

There is no requirement for a transformer "secondary disconnect", but you will need some ocpd to comply with 240.21(C) and possibly for transformers secondary protection 450.3(B) (sorry if I am nitpicking your terminology a little )

A lot of engineers are actually afraid to do that. I've personally never seen a transformer without a secondary disconnect and not within sight. They usually overkill the design by adding primary and secondary within sight of the transformer. I guess that would be me lol

 

[electrofelon]

A lot of engineers are actually afraid to do that. I've personally never seen a transformer without a secondary disconnect and not within sight. They usually overkill the design by adding primary and secondary within sight of the transformer. I guess that would be me lol

IMO most engineers shouldn't be designing this basic electrical stuff as they often don't have field experience and don't know the best way to do it and often just end up wasting the client's money. A good "design-build" electrical contractor is a much better choice.

The rules in 240.21(c)will often make the "secondary disconnect" within sight.

 

[Tainted]

IMO most engineers shouldn't be designing this basic electrical stuff as they often don't have field experience and don't know the best way to do it and often just end up wasting the client's money. A good "design-build" electrical contractor is a much better choice.

The rules in 240.21(c)will often make the "secondary disconnect" within sight.

Usually 25 feet is not within sight. or are you referring to 240.21(c)(2)

 

[electrofelon]

Usually 25 feet is not within sight. or are you referring to 240.21(c)(2)

Sure, 25 ft may not be in sight. Why does it matter if it's in sight?

 

[Tainted]

Sure, 25 ft may not be in sight. Why does it matter if it's in sight?

This might be a stupid question but if I put the primary disconnect within sight of the transformer, does the secondary disconnect have to be within sight of the transformer too? I assume not. How far can the secondary disconnect be allowed to be?

 

[infinity]

The primary disconnect does not need to be within sight.

 

[Tainted]

The primary disconnect does not need to be within sight.

as long as the primary disconnect is lockable?

 

[jim dungar]

How far can the secondary disconnect be allowed to be?

This would be dependent on which subparagraph of 240.21(C).