EPO disconnecting means?

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jasonconner

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Does the code consider an EPO switch a disconnecting means?

In my opinion the NEC's definition of "disconnecting means" could allow an EPO switch to be classified as such. The definition reads:

"A device, or group of devices, or other means by which the conductors of a circuit can be disconnected from their source of supply."
 
Re: EPO disconnecting means?

Are you trying to qualify a disconnect means for IT equipment? If so, I believe a typical EPO would qualify per the requirement of 645.10
 
Re: EPO disconnecting means?

No. I am using this for an indoor hot tub. An EPO is required by code, and the disconnecting means is required to be within sight of the equipment per the 2005 code.

I would like to locate the disconnect in another room.
 
Re: EPO disconnecting means?

EPO = Emergency Power Off
Term was born in the early days of computer rooms and the disconnect requirement. It might have been or is being applied elsewhere.

I don't have a 2005 (were on the '99), so I won't go there.

It is interesting that the Code recognizes a pushbutton as a disconnecting means in 645.10 (last sentence).

Does that mean we can use one to meet the the disconnect req's of 430 and 440?
 
Re: EPO disconnecting means?

I don't know if he is right, but our local inspector won't allow it. We often draw plans for the installation of medical imaging equipment (CT's, MRI's, Xray units). The vendors all show a circuit breaker disconnect in the equipment room, and an EPO in the control room. We always add another circuit breaker disconnect in the control room per our inspector's requirement.

Edit: But on second thought, those E stops the equipment vendors always show are shunt trips. Not as fail safe as using an EPO and a control relay.

Steve

[ February 22, 2005, 12:49 PM: Message edited by: steve66 ]
 
Re: EPO disconnecting means?

In my opinion, a control switch of any type is not a disconnect switch. A disconnect switch must directly disconnect the power conductors.
Don
 
Re: EPO disconnecting means?

I think the pushbutton EPO should work with a shunt trip circuit breaker supplying power to your hot tub. You may need a relay inbetween to maintain an open circuit to the shunt trip, depending on how you design it. You may just get away with a regular unfused switch, similar to a light switch rated to cover the input current and volatage of the hot tub.
 
Re: EPO disconnecting means?

Larry,
It is interesting that the Code recognizes a pushbutton as a disconnecting means in 645.10 (last sentence). Does that mean we can use one to meet the?disconnect req's of 430 and 440?
Click to expand...
The power shut off for an Article 645 room is not required to be a disconnect in the normal sense of the word. Article 645 requires an emergency shut down switch. This could be a disconnect, but most likely would be some control device such as a pushbutton operating a remote contactor or other such device. The disconnects required in 430 and 440 are for maintenance lockout purposes. They must disconnect the power circuit conductors to allow safe servicing of the equipment. A pushbutton or other type of remote operator is not suitable for use as a service disconnect.
Don

[ February 22, 2005, 03:51 PM: Message edited by: don_resqcapt19 ]
 
Re: EPO disconnecting means?

The Idea for the EPO switch and a contactor should meet code. The definition of a disconnecting means per article 100 is
"Disconnecting Means. a device, or group of devices,or other means by which the conductors of a circuit can be disconnected from their source of supply." and article 230 even mentions a remote control device to actuate the service disconnecting means (just for comparison) A disconnecting means should be able to be a plug, switch, disconnect, breaker, shunt trip, contactor as long as the device disconnects the source of supply. Shouldn't it?
 
Re: EPO disconnecting means?

Originally posted by don_resqcapt19:
Click to expand...
The power shut off for an Article 645 room is not required to be a disconnect in the normal sense of the word. Article 645 requires an emergency shut down switch. This could be a disconnect, but most likely would be some control device such as a pushbutton operating a remote contactor or other such device. The disconnects required in 430 and 440 are for maintenance lockout purposes. They must disconnect the power circuit conductors to allow safe servicing of the equipment. A pushbutton or other type of remote operator is not suitable for use as a service disconnect.
Don [/QUOTE]

Don
I agree, however the term used in 645 is disconnecting means. It's the title of the section. My point is clarification is needed here.
An EPO does meet the definition in 100.

Perhaps the same clarification is needed in 430, 440 and 680 for the disconnecting means as is found in 230.
 
Re: EPO disconnecting means?

I don't agree that an EPO meets the rule for a disconnect.
Disconnecting Means. A device, or group of devices, or other means by which the conductors of a circuit can be disconnected from their source of supply.
Click to expand...
I read this as saying that the operating device itself must directly open the circuit conductors. Some device that causes a second device to open the circuit conductors is not a disconnect.
PS...I think this is also involves an OSHA rule.
Don

[ February 22, 2005, 07:37 PM: Message edited by: don_resqcapt19 ]
 
Re: EPO disconnecting means?

Don
OSHA rule aside, the EPO would be "other means"

btw, personally I agree that a disconnecting means should be a manually operated switch not relying on any electrical components which could fail or be mis-wired.
 
Re: EPO disconnecting means?

Larry,
I don't agree that the "other means" would permit the EPO as the requied disconnect. The device that you physically operate, must directly open the circuit conductors.
Don
 
Re: EPO disconnecting means?

Originally posted by don_resqcapt19:
Larry,
I don't agree that the "other means" would permit the EPO as the requied disconnect. The device that you physically operate, must directly open the circuit conductors.
Don
Click to expand...
Don
"other means" leaves it wide open. Anything that accomplishes the task.

Am I missing something?
 
Re: EPO disconnecting means?

Larry,
It is my opinion that the "means" no matter what is used, must directly open the circuit conductors, not cause a second device or means to open those conductors.
Don
 
Re: EPO disconnecting means?

In general terms, ?means? is a description of ?what? is to be acheived as an end result, rather than ?how? it is achieved. CMP 11 thinks so too because they want Don to be right with respect to motors. This is why they have specific declarations of intent in 430.110 and 440.11 and their own definitions of ?controllers? in 430.81(A).
 
Re: EPO disconnecting means?

Ok
As Bob pointed out, I spoke w/out looking in regards to 430 and 440. Don, I concede.
Section 680-12, however, leaves it wide open as to the type of disconnscting means.
 
Re: EPO disconnecting means?

Larry,

Just so you know - you are "generally" right. "Means" is whatever achieves the stated result. Don is right that many CMPs want that result achieved in specific ways; or, in some cases, they augment the "intended result" with additional requirements that limit the "how."
 
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