Cover does not open when in on position

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JustWork

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Hello to you all that view this post. We have been doing alot of elevator related work and I have always knew that the disconnect door for the disconnect that feeds the elevator could not open while the switch was in the on position. Until just now I never looked for it in the code book or had a need to. Would anyone know if this is listed in the NEC? I thought it would have been listed in 430.109 or 110 or even 620 Any information would be greatly appreciated.
 
There is no listing for Disconnect in the Index, while Disconnecting means is.

Remember that a "Switch" is a "Disconnecting Means"(which are both listed), Article 404 and (through) especially 404.6
is about the closest to your orginal OP but not an exact match as asked!
 
I've searched NEC and UL and can not find the reference that is in my head. Some switches have the door interlock and some do not and I can't recall the particulars as to why but I think it has to do with voltage ratings.
We encountered this as a question on AC disconnects and the fact that some general duty fusible safety switches allow entry and others don't and research reveled why there was a difference but that reason escapes me.
Hopefully someone will enlighten us.
 
augie47 said:
I've searched NEC and UL and can not find the reference that is in my head. Some switches have the door interlock and some do not and I can't recall the particulars as to why but I think it has to do with voltage ratings.
We encountered this as a question on AC disconnects and the fact that some general duty fusible safety switches allow entry and others don't and research reveled why there was a difference but that reason escapes me.
Hopefully someone will enlighten us.
Click to expand...

this is what your looking for:)


NFPA79 and UL508A
Industrial Machinery Operating Handle Requirements
NFPA79 - 6.2.3.1 Door interlocked with operating mechanism in “ON” position.
UL508A - 66.1.5 A door of an enclosure that gives access to uninsulated live parts operating
at 50 volts rms ac or 60V dc or more shall be interlocked with the disconnecting means
such that none of the doors can be opened unless the power is disconnected.
ABB flange solution: Operating handle provides door interlock when the switch is in the
“ON” position. Available for non-fusible switch products from 30-1200 amps and for fusible
products from 30-800 amps.
ABB rotary solution: Door mounted operating handle provides door interlock when the
switch is in the “ON” position.
Flange Through the Door
Door Closed Door Open Door Closed Door Open


Its on page 5 or 6 on this link...http://www.abb-control.com/pdf/white/LV080.pdf
 
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Leo,
Both NFPA 78 and UL508A apply only to industrial control panels per their scope statements. Those rules do not apply to the typical disconnects installed by electricians under the rules found in the NEC.
 
I would be looking into just the 3 phase disconnect that we would install for the feed to the elevator controller. Not the the elevator controller itself. Our issue is that the elevator inspector is requesting that this disconnect not be operable, able to switch it on and off with the door open. Thanks
 
JustWork said:
I would be looking into just the 3 phase disconnect that we would install for the feed to the elevator controller. Not the the elevator controller itself. Our issue is that the elevator inspector is requesting that this disconnect not be operable, able to switch it on and off with the door open. Thanks
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I would say that your inspector is asking for something improbable. I should not admit this, but in general, I am able to defeat most safety interlocking devices.
 
There is no general Code requirement that a disconnecting means may only be operated with its enclosure closed. (Some disconnecting means may not have an enclosure at all.) However, depending on the application, the rules may dictate that disconnecting means are only accessible to qualified persons. For elevators those rules are in 620.51.
 
I understand section 620 and we all can defeat an interlocking device, as for the inspector asking for something improbale, The disconnect that he is requesting is and has been out there for many years. Most elevator and some electrical inspectors have considered this a violation should the enclosure door open when switch is on. I am just trying to locate this requirement in print some where. I look at it this way if the interlock is and has been installed on three phased fused disconnects why are they installed and who is instructing or recommends that they be installed because the manufacturer wouldnt put them in if they didnt have to. :-?
 
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JustWork said:
... I look at it this way if the interlock is and has been installed on three phased fused disconnects why are they installed and who is instructing or recommends that they be installed because the manufacturer wouldnt put them in if they didnt have to. :-?
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Perhaps NEMA...???
 
A little off subject but never defeat a kirk key interlock they are aways there for a reason.

Depending on the application sometimes switches are not rated for load break duty.
 
JustWork said:
... Most elevator and some electrical inspectors have considered this a violation should the enclosure door open when switch is on. ... :-?
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If they believe it to be a violation, they should also be able to cite their source.
 
Smart $ said:
Perhaps NEMA...???
Click to expand...
This is a good point. The relationship between the product standards bodies, say NEMA or UL, and the NEC is not always clear cut. NEMA and UL will usually alter their manufacturing or test standards to match the NEC (often kicking and screaming) but there is no mechanism for making an NEC installation match the product standards other than a reference that a product must be listed or labeled.

I happened to be at one NFPA Tech Committee meeting, where the "end-users" were complaining that various safety features were permitted to have defeaters for certain product lines. The UL representative basically said - "It was you guys that demanded it."
 
Ok everyone and thank you for the help. After a very interesting search here is the answer to my question. The switch design and construction is covered as we know by NEMA andlisted as NEMA KS1 and also UL 98. Disconnect switches shall be classified as general duty(gd) and heavy duty (hd)

GD= the voltage, amperes, and horsepower ratings of GD switches at 60 hz are up to and including 240 volts, 600 amperes, and 200 hp.

HD = the voltage, amperes, and horsepower ratings of HD switches at 60 hz are up to and including 600 volts, 1200 amperes, and 50 hp.

So as for NEC requirement we would naturally install the the disconnect switch that is required by voltage, amperes, and horsepower and in doing so this would dictate the mechanical interlock for the door. Here are a couple of links that I used and are very informative. http://ulstandardsinfonet.ul.com/
http://www.nema.org/stds/ks1.cfm this site you have to register with but was worth the time. Please let me know what you think of them.:cool:
 
jumper said:
[/color][/b]I should not admit this, but in general, I am able to defeat most safety interlocking devices.
Click to expand...
Agreed. Most can be opened when on, although sometimes it's not so obvious, and just about any can be switched on when open, if you manually move whatever the door closing does.
 
JustWork said:
Ok everyone and thank you for the help. After a very interesting search here is the answer to my question. The switch design and construction is covered as we know by NEMA andlisted as NEMA KS1 and also UL 98. Disconnect switches shall be classified as general duty(gd) and heavy duty (hd)

GD= the voltage, amperes, and horsepower ratings of GD switches at 60 hz are up to and including 240 volts, 600 amperes, and 200 hp.

HD = the voltage, amperes, and horsepower ratings of HD switches at 60 hz are up to and including 600 volts, 1200 amperes, and 50 hp.

So as for NEC requirement we would naturally install the the disconnect switch that is required by voltage, amperes, and horsepower and in doing so this would dictate the mechanical interlock for the door. Here are a couple of links that I used and are very informative. http://ulstandardsinfonet.ul.com/
http://www.nema.org/stds/ks1.cfm this site you have to register with but was worth the time. Please let me know what you think of them.:cool:
Click to expand...

I'm lazy :) Save me some work. Did you find a "key" where the requirement changes, for instance, GD does not requires interlock, HD does, etc. ?
 
Not lazy just working smart I would do the same :). In NEMA KS1 page 20 section 2.6.4 heading of Mechanical interlock states Heavy duty switches rated 30-1200 amperes and having type 1,3,3r,5,12,12k, or 13 enclosure shall have the box, cover, and switch operating mechanism mechanicaly interlocked so that the main cover of the cabinet(and, if provided an auxiliary cover giving access to the main fuses) (1) is normally prevented from being opened when the switch contacts are in the closed position, and (2) the switch contacts are normally prevented from being closed when the main or auxiliary cover of the switch cabinet is open. What I got from the classification of switches GD or HD, is a General Duty switch is only good for up to and including 240 volts. So if I had installed a 100 amp 3 phase 600 volt rated disconnect switch and it was being supplied by 3 phase 208 volts it would still require the mechanical interlock because of the rating of the switch I installed. Classification of switches is in section 4 GD is 4.1 HD is 4.2

Hope this works for you.
Tony
 
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