Locked service disconnect

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smallfish

Senior Member
Location
Detroit
A fused service disconnect will be placed outside a medical clinic building nearest the point of entry (the inside is too cluttered). Is it permissible to lock "on" the service disconnect so vandals are not able to tamper with the operation of the disconnect? Downstream of the service disconnect, inside the building are electrical panels that the occupant has ready access to. I believe Sec. 230.92 permits this, and if so, I wonder in the back on my mind "Is it safe to do this?" Thanks
 

raider1

Senior Member
Staff member
Location
Logan, Utah
Yes it is permissible to lock a service disconnect.

Also, being locked does not neccessarly mean the service disconnect is not readily accessible. If the persons to whom the service disconnect is required to be readily accessible have the keys then by the definition in Article 100 the service disconnect would be readily accessible.

Here is a quote from teh 2005 NEC handbook:
The definition of readily accessible does not preclude the use of a locked door for
service equipment or rooms containing service equipment, provided those for whom
ready access is necessary have a key (or lock combination) available. For example,
230.70(A)(1) and 230.205(A) require service-disconnecting means to be readily
accessible. Section 225.32 requires that feeder disconnecting means for separate
buildings be readily accessible. A commonly used, permitted practice is to locate the
disconnecting means in the electrical equipment room of an office building or large
apartment building and to keep the door to that room locked to prevent access by
unauthorized persons. Section 240.24(A) requires that overcurrent devices be so
located as to be readily accessible.

You might also want to check with the local fire marshal, sometimes they have a local requirment to have an exterior means avaliable to them to disconnect the power in the case of a fire. I have installed lock boxes next to locked service disconnects. The fire department has the key to the lock box and inside of the box is a key to the service disconnect.

Chris
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
raider1 said:
You might also want to check with the local fire marshal, sometimes they have a local requirment to have an exterior means avaliable to them to disconnect the power in the case of a fire. I have installed lock boxes next to locked service disconnects. The fire department has the key to the lock box and inside of the box is a key to the service disconnect.

Chris


Wouldn't you think that the FD would have little trouble opening a locked disconnect switch in an emergency?
 

raider1

Senior Member
Staff member
Location
Logan, Utah
infinity said:
Wouldn't you think that the FD would have little trouble opening a locked disconnect switch in an emergency?

That's why I said to check with the local fire marshall.;)

I have installed lock boxes next to the disconnect that contain the key for the disconnect lock. The fire department has the key to the lock box.

I have also installed a shut trip switch at the exterior of a building where the service is installed within the building. This was not a NEC requirment but a mandate from the fire marshall.

Chris
 

raider1

Senior Member
Staff member
Location
Logan, Utah
Trevor, here is what I have installed next to the service disconnect.
43ow0.gif


The only difference was that it was keyed and not a pushbutton type.

Chris
 

iwire

Moderator
Staff member
Location
Massachusetts
Around here almost all commercial buildings get a "Knox Box" keyed to the local fire departments specs.

Inside then will be keys for building entry, fire alarm keys etc.

3200_SL_BK.gif
 

raider1

Senior Member
Staff member
Location
Logan, Utah
iwire said:
Around here almost all commercial buildings get a "Knox Box" keyed to the local fire departments specs.

Inside then will be keys for building entry, fire alarm keys etc.

3200_SL_BK.gif

Same around here. Your picture is more typical than mine, I just couldn't remember the name of the box so I just found a picture of a "lock box" :D

Chris
 

e57

Senior Member
Knox Box is an easy way - if required. If not just lock it... The FD has a few methods of their own to disconnect power - pulling meters, and I've seen them hot-stick overhead drops pretty lickity split...
 
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