Absurdly Simple Question II: Transformers

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For what its worth...

For what its worth...

in one form or other an "isolating means" has been a general requirement (including transformers) for over 600V equipment since I've been in the business. Currently, it's in Section 490.22. Technically, it may not be a "disconnecting means" because it isn't necessarily required to be capable of interrupting load currents.
 
iwire said:
It is a fact that the only reason offered for this code change was an opinion and not evidence of a problem with the previous code cycles
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Which is a poor reason for the change.

Roger
 
iwire said:
So in other words, 'Just because' without and real issue being used to substantiate the need.:roll:
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No...it means you are assuming on your own view versus knowing why it was added. What makes sense to one person who knows why it changed may not to someone who does not . I say submit a proposal and support your stance...otherwise accept it, teach it and embrace it.
 
roger said:
Which is a poor reason for the change.

Roger
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I disagree...not all CMP's work close together as changes take place (as you know) so sometimes it takes awhile for things that are common in one area of the code to migrate to others. As stated in my response of why it was proposed.....it is already common practice with motors and so on so it begs to wonder why everyone would be concerned over it.
 
radiopet said:
No...it means you are assuming on your own view versus knowing why it was added. What makes sense to one person who knows why it changed may not to someone who does not . I say submit a proposal and support your stance...otherwise accept it, teach it and embrace it.
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You should proably read the entire thread.

Can you explain why a transformer is more likely to need servicing than a panel?


BTW, What does it take for me to get my own thread on your forum questioning how long I have been in the trade?

I am very jealous that George gets special treatment. :grin:
 
radiopet said:
I disagree...not all CMP's work close together as changes take place (as you know) so sometimes it takes awhile for things that are common in one area of the code to migrate to others.
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There is no need for things to 'migrate' either a proposal has the ability to stand on it's own or it does not.

This one does not.


As stated in my response of why it was proposed.....it is already common practice with motors and so on so it begs to wonder why everyone would be concerned over it.
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Typical civil servant attitude.

It concerns me that the NEC is always getting more restrictive .... many times without good reason.
 
iwire said:
There is no need for things to 'migrate' either a proposal has the ability to stand on it's own or it does not.

This one does not.




Typical civil servant attitude.

It concerns me that the NEC is always getting more restrictive .... many times without good reason.
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Opinions are what they are.....I have no problem with that

Here is what was stated by NECPLUS and I have no problem with it....


This requirement is new in the 2011 Code to require a disconnecting means for a transformer. This requirement is intended to enhance safety for the qualified worker required to maintain the transformer. This enhanced safety is especially needed in installations utilizing the requirements of 240.21(B)(3) where there may be several transformers in different locations all tapped from one feeder and it may be impractical to de-energize the feeder to work on one of the transformers. The disconnect is required to be located within sight from the transformer, but may be in a remote location if it is lockable. The location of any remote disconnect is required to be marked on the transformer.
 
I read it...Did You?

9-175 Log #659 NEC-P09 Final Action: Accept in Principle in Part
(450.14)
_______________________________________________________________
Submitter: Harold F. Willman, Colorado Code Consulting
Recommendation: Add new text to read as follows:
450.14 Transformer disconnecting means. Transformers shall have a
disconnecting means located within sight of the transformer.
Substantiation: In larger commercial buildings and multistory buildings, many
transformers have the overcurrent protection and the disconnecting means for
the transformer at the main distribution center. This main distribution center is
normally located on the bottom floor of the multistory building or in an
electrical room of a large commercial building. Transformers are scattered
throughout the building without signage on the transformer indicating the
location of disconnecting means for the transformer. By installing a
disconnecting means within sight of the transformer, maintenance and
modification of the primary and/or secondary side of the transformer would be
safer for the electricians working on the transformer. The lock out-tag out
method is not always available in the main distribution center.
Panel Meeting Action: Accept in Principle in Part
CMP-9 accepts in principle the concept of a disconnect provision for
transformers. CMP-9 rejects the requirement that this disconnecting means
must be located within sight of the transformer.
Panel Statement: See the action on Proposal 9-176 for the final requirement
that addresses the concept in this proposal that is being accepted.
Number Eligible to Vote: 12
Ballot Results: Affirmative: 12
_______________________________________________________________
9-176 Log #3821 NEC-P09 Final Action: Accept in Principle
(450.14)
_______________________________________________________________
Submitter: James J. Rogers, Bay State Inspectional Agency
Recommendation: Add new text to read as follows:
450.14 Disconnecting Means. Transformers other than listed class 2 or class
3 transformers shall have a disconnecting means located either in sight of the
transformer or remotely provided the remote disconnect is capable of being
locked in the off position. When the disconnecting means is located remote
from the transformer the locking means required shall remain in place whether
or not the locking means is installed.
Substantiation: Requiring a disconnecting means for a transformer is intended
to enhance safety for the qualified individual that is required to work on the
transformer. This is especially true in installations utilizing the requirements of
240.21(B)(3) whereby there may be several transformers in different locations
all tapped from one feeder and it may be impractical to de-energize the entire
feeder system to work on one of the transformers.
Panel Meeting Action: Accept in Principle
Revise the rule to read as follows: ?Transformers, other than Class 2 or Class
3, shall have a disconnecting means located either in sight of the transformer or
in a remote location. Where located in a remote location, the disconnecting
means shall be lockable, and the location shall be field marked on the
transformer.?
Panel Statement: CMP-9 has made editorial changes to avoid a run-on
sentence, used ?open? instead of ?off? for the disconnect position in
accordance with customary code usage, used ?where? instead of ?when?
because it is a question of place and not time, and removed the listing
limitation on the Class 2 and 3 transformers because it has no bearing on
whether a disconnecting means needs to be installed. The lockable wording
correlates with the task group results reported in Proposal 9-201.
Number Eligible to Vote: 12
Ballot Results: Affirmative: 12
Comment on Affirmative:
YOUNG, R.: The disconnecting means should be lockable in the open
position whether or not the disconnecting means is mounted either within sight
of the transformer or in a remote location.
 
I agree with the others on here making safe, safer with this transformer Disconnect is rediculas.

I worked around dry type transformers in commercial ,industrial and residential for 35 yrs.and never had to service them. And when we did we just blew the dust out of them.When they went bad they usually trip the OCP and maybe a few sparks now if the reason is maybe to save equipment from single phasing and burning up, well shouldn't they at least give this as a reason?

I thought the NEC had the bases covered pretty good as far as accidents and fires by requiring 112.5 KVA and above Dry types and flamable oil types to be located in a separate fire proof vaults when installed indoors.

Just my two cents worth.
 
radiopet said:
Opinions are what they are.....I have no problem with that

Here is what was stated by NECPLUS and I have no problem with it....
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Which is just an opinion.

I am looking for any sort of fact that shows the lack of a disconnecting means has been a problem.
 
The rule really doesn't require anything new, other than the label telling you where the remote disconnect is located.
 
don_resqcapt19 said:
The rule really doesn't require anything new, other than the label telling you where the remote disconnect is located.
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I disagree....the entire 450.14 is new and the lockable disconnect for remote is new. Other than the label issue are you saying that on all transformer primary OCPD's you made sure it was lockable?
 
radiopet said:
Probably right next to the facts that require the same for motors....;)
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I have seen plenty of pictures of people caught up in machinery, never seen or heard of anyone caught up in a transformer. Or I am sure it happens just not very often at all. When it does happen it is because someone chose to work it live.

Motor circuits are also commonly remotely controlled ....again not so often with the supply to a transformer.



But be that as it may, can you explain why a transformer is more likely to requires servicing and less likely to be impracticable to shut off than a panelboard?
 
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