Oversize breaker with adjustable trip

[dema]

I personally believe that a contractor had a bad transfer switch that he unloaded on one of my customers. He put in a Siemens 3200A transfer switch on a 1200A application. Currently the application is not code, he put in a 2000A trip plug but there is no lock on the door so I don't believe that adjusting an adjustable trip meets NEC 240. However, the switch has not worked properly during testing, the CT's look old and in general I don't like the installation. The transfer switch is breaker based and I prefer double throw. In general I don't like having a bigger breaker than what is called for and I don't see why anyone would do it for a good reason.

Please comment. Help me to get this bad installation completely ripped out instead of having the contractor come back and mess with it and mess with it like he has for six weeks or more. The building is dark.

As many of you know I am a design engineer. Feel free to disagree with me - I would love to be prepared for whatever arguments I may receive. Thanks.

 

[jumper]

What did the contract spec?

 

[jim dungar]

...there is no lock on the door so I don't believe that adjusting an adjustable trip meets NEC 240. ...

A lock is not required. 240.6(C)(1) can be met with nothing more than a 'wire tie', the requirement is for removable and sealable covers.

 

[dema]

The original design wasn't by me, but was exactly like I would do it - a service entrance disconnect and an ASCO transfer switch - 1200A. The original switch was damaged, and the contractor brought in this 3200A breaker based ATS.

 

[dema]

They are using this breaker based transfer switch as their service entrance disconnect.

 

[Jraef]

If the original specification called for the ATS to be listed under UL1008, chances are about 99% that the scheme using the Siemens power breakers was not listed as such. People make ATS units from CBs all the time and get them listed under UL1008, but they are SOLD as listed Automatic Transfer Switches. People also "roll their own" transfer switches by using breakers and Transfer Controllers, but those are NOT listed as official Automatic Transfer Switches for use in "Emergency Systems" as defined in Article 700 of the NEC.

 

[iwire]

The transfer switch is breaker based and I prefer double throw. In general I don't like having a bigger breaker than what is called for and I don't see why anyone would do it for a good reason.

This work was not done for you, or paid for by you, so I am at a loss why what you like has anything to do with it. :huh:

It really comes across to me as sour grapes. Maybe I am mistaken.

 

[dema]

I have been hired to do a job. I am being paid to make it my business.

I have great respect for electrical contractors and for the fact that I do not know everything that a contractor knows. The two professions should be symbiotic - not competitive. We should play on a team, not as adversaries.

 

[dema]

A winner

A winner

If the original specification called for the ATS to be listed under UL1008, chances are about 99% that the scheme using the Siemens power breakers was not listed as such. People make ATS units from CBs all the time and get them listed under UL1008, but they are SOLD as listed Automatic Transfer Switches. People also "roll their own" transfer switches by using breakers and Transfer Controllers, but those are NOT listed as official Automatic Transfer Switches for use in "Emergency Systems" as defined in Article 700 of the NEC.

Thank you. I appreciate the input. I checked and cannot find any listing as a transfer switch on the equipment.

 

[dkidd]

If it is an Article 702 system, the switch is not required to be listed.

 

[mpoulton]

Plans and specs?

Plans and specs?

This doesn't sounds like a code problem or even a functional problem to me, only a matter of personal preference. Does the new installation comply with the plans and specs? If not, then that's your out. It's non-compliant and you can make them do it according to plan. If it does comply though, then I think you may need to take a look at exactly why you don't like this solution even though it matches your design docs. Does the customer care? Enough to pay more to have it done the way you want?

 

[dema]

The customer has various issues which I am not free to discuss further. We are never truly anonymous. I was contacted to help with the issues. My main argument was that the original plans and specs were not followed. The UL1008 argument was also very helpful.

Thank you for your input.