Transfer Switches

[frankelectric]

Hello Mike:

I am planing to install an automatic transfer switch next to the service entrance disconnect. I need to know if there is any violation if i use the same raceway for the load and normal power source wiring.

Your response will be apreciated.

Regards; Frank Rodriguez
Frank Electric Services,Inc.

{Moderator's Note: Edited to remove personal contact information. If you wish to contact this person, please send a Private Message.}

[ September 29, 2005, 03:32 PM: Message edited by: charlie b ]

 

[iwire]

Re: Transfer Switches

It depends, is this truly a required emergency generator or is it an optional stand by unit?

By the way you need to remove your email address from your post.

Bob

 

[charlie b]

Re: Transfer Switches

You will have to deal with the impact of more than three current-carrying conductors in the same raceway. But what is the purpose of the "other" power source? Is it "emergency," or "legally required standby," or "optional standby"?

 

[frankelectric]

Re: Transfer Switches

Originally posted by charlie b:
You will have to deal with the impact of more than three current-carrying conductors in the same raceway. But what is the purpose of the "other" power source? Is it "emergency," or "legally required standby," or "optional standby"?

 

[frankelectric]

Re: Transfer Switches

Originally posted by frankelectric:

Originally posted by charlie b:
You will have to deal with the impact of more than three current-carrying conductors in the same raceway. But what is the purpose of the "other" power source? Is it "emergency," or "legally required standby," or "optional standby"?

 

[iwire]

Re: Transfer Switches

Frank, use this

button located at the bottom of the page to post more information.

 

[frankelectric]

Re: Transfer Switches

The generator will be used as a stanby power source in a residential unit.

 

[iwire]

Re: Transfer Switches

As it is an optional standby unit it is covered in Article 702 which dose not prohibit mixing the normal and generator power in the same conduit.

I am not sure if you have to worry about derating.

If only one set of conductors can be carrying current at one time you can forget the derating.

 

[roger]

Re: Transfer Switches

Frank, as Iwire says, you will find your information in 702.9 to be exact.

702.9 Wiring Optional Standby Systems
The optional standby system wiring shall be permitted to occupy the same raceways, cables, boxes, and cabinets with other general wiring.

Roger

 

[frankelectric]

Re: Transfer Switches

Remember that both sets of wires would be carrying current while you are connected to the normal utility power source.

My concern is; in case of a short circuit in the raceway; it may damage the insulation of the wires causing a direct contact between two wires and if the generator is running while in a utility power failure, it may energize the normal power lines provoking a fatal accident to people working on the lines.

The probabilities of this problem are very minimum or maybe never happens but we never know.

The practice of this type of installation is being doing very often in my country (PR)Including commercial and residential applications.

This concern may be is not a NEC violation but the probabilities exists.

Please; correct me if i am wrong.

Thanks.

 

[iwire]

Re: Transfer Switches

No doubt Frank, 'stuff' happens.

Generally I believe they make code sections for hazards that are happening not necessarily for what may happen.

90.1 Purpose.
(A) Practical Safeguarding. The purpose of this Code is the practical safeguarding of persons and property from hazards arising from the use of electricity.

 

[stevearne]

Re: Transfer Switches

This is a Code topic, non an Instructor topic, so I am moving this Please feel free to continue the discussion in the appropriate code forum



[ October 05, 2005, 12:09 PM: Message edited by: stevearne ]