Disconnects

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jog

Member
I am doing a ductless heat pump job where my disconnects are 9 feet off the ground do I have to use Non-fused disconnect, I am wondering if this falls under the main disconnect rule which the main disconnect cannot be over 6 foot seven inspector told me I would have to go with nonfused if I went over 6 foot seven and I am not able to find that in the codebook
 

augie47

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Location
Tennessee
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State Electrical Inspector (Retired)
Keep in mind there are exceptions to the 6'7" rule in 404.8 (especially exception #2).
I know of no rule that disconnects above the 6'7" point need be unfused.
 

augie47

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Tennessee
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State Electrical Inspector (Retired)
The only other consideration I can think of is the fact that NF disconnects are rated 10k AIC so one needs to be aware of the available fault current.
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
Some AHJ's feel that 110.26 working spaces is applicable to fused disconnects. That is probably the issue here.
 

kwired

Electron manager
Location
NE Nebraska
Some AHJ's feel that 110.26 working spaces is applicable to fused disconnects. That is probably the issue here.
Yet some of those same guys will allow disconnect with overcurrent protection within suspended ceiling space for an AHU but absolutely won't allow outdoor unit disconnects that don't have full clearances mentioned in 110.26:roll:
 

augie47

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Tennessee
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State Electrical Inspector (Retired)
Yet some of those same guys will allow disconnect with overcurrent protection within suspended ceiling space for an AHU but absolutely won't allow outdoor unit disconnects that don't have full clearances mentioned in 110.26:roll:

raises hand, "Me":bye: Thankfully the '17 Code addressed that to some degree.
 

infinity

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Location
New Jersey
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Disconnects for specific equipment is permitted to be adjacent to the equipment even if it's 9' in the air. Not sure what code section would disallow fused disconnects.
 

kwired

Electron manager
Location
NE Nebraska
Disconnects for specific equipment is permitted to be adjacent to the equipment even if it's 9' in the air. Not sure what code section would disallow fused disconnects.

I believe there is wording something like "accessible from the equipment", though that still can lead to some misunderstanding of what is allowed.
 

infinity

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Location
New Jersey
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Journeyman Electrician
I believe there is wording something like "accessible from the equipment", though that still can lead to some misunderstanding of what is allowed.

Every Home Depot that I have been in has a ceiling mounted transformer with an adjacent disconnect 15'-20' above the floor. This is a pretty common installation practice. :)
 

augie47

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Location
Tennessee
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State Electrical Inspector (Retired)
We agree height is not normally a problem due to the exception in 404.6, but I concur with kw that the other requirements of 110.26 are often questionable.
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
We agree height is not normally a problem due to the exception in 404.6, but I concur with kw that the other requirements of 110.26 are often questionable.

Personally, I think fused disconnects shouldn't be covered by 110.26, but I think the code needs to be more explicit about that. A fuse can be checked with an ohmmeter, and there is no other reason to enter the disconnect while hot so it should have no different rules than a non-fused disconnect has.
 

infinity

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Location
New Jersey
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Journeyman Electrician
Personally, I think fused disconnects shouldn't be covered by 110.26, but I think the code needs to be more explicit about that. A fuse can be checked with an ohmmeter, and there is no other reason to enter the disconnect while hot so it should have no different rules than a non-fused disconnect has.

I agree, in fact you first need to physically need defeat the safety feature that prohibits the opening of the disconnect when it's energized.
 

Strathead

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Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
I agree, in fact you first need to physically need defeat the safety feature that prohibits the opening of the disconnect when it's energized.

To play devil's advocate though, you need to delete the safety for the typical industrial control panel as well, but I wouldn't be for eliminating 110.26 for that.
 

busman

Senior Member
Location
Northern Virginia
Occupation
Master Electrician / Electrical Engineer
Unfortunately, in my opinion, 110.26 makes very little sense in light of NFPA 70E requirements. Because it requires the following process before something can be considered de-energized, I believe all equipment that could be energized requires the 110.26 clearances since it would need to be tested before being considered de-energized.


  1. Determine all possible sources of electrical supply to the specific equipment. Check applicable up-to-date drawings, diagrams, and identification tags.
  2. After properly interrupting the load current, open the disconnecting device(s) for each source.
  3. Wherever possible, visually verify that all blades of the disconnecting devices are fully open or that drawout-type circuit breakers are withdrawn to the fully disconnected position.
  4. Apply lockout/tagout devices in accordance with a documented and established policy.
  5. Use an adequately rated voltage detector to test each phase conductor or circuit part to verify they are de-energized. Test each phase conductor or circuit part both phase-to-phase and phase-to-ground. Before and after each test, determine that the voltage detector is operating satisfactorily.
  6. Where the possibility of induced voltages or stored electrical energy exists, ground the phase conductors or circuit parts before touching them. Where it could be reasonably anticipated that the conductors or circuit parts being de-energized could contact other exposed energized conductors or circuit parts, apply ground connecting devices rated for the available fault duty.
 

kwired

Electron manager
Location
NE Nebraska
Personally, I think fused disconnects shouldn't be covered by 110.26, but I think the code needs to be more explicit about that. A fuse can be checked with an ohmmeter, and there is no other reason to enter the disconnect while hot so it should have no different rules than a non-fused disconnect has.
An example that has been brought up here many times in the past - Air conditioner not working, HVAC tech gets called, first thing he does is check for voltage at the disconnect. No voltage? tell them to get an electrician.

How does that not fit into "likely to require examination, adjustment, servicing, or maintenance while energized" mentioned in 110.26?

Since NEC is pretty vague in not telling us what is "likely" to have those requirements - if taken to an extreme there is very little that has access to conductors that this doesn't apply to. How many times when troubleshooting does one take voltage readings at locations that don't have 110.26 working space? Is somewhat unavoidable with a lot of applications.
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
An example that has been brought up here many times in the past - Air conditioner not working, HVAC tech gets called, first thing he does is check for voltage at the disconnect. No voltage? tell them to get an electrician.

How does that not fit into "likely to require examination, adjustment, servicing, or maintenance while energized" mentioned in 110.26?

Since NEC is pretty vague in not telling us what is "likely" to have those requirements - if taken to an extreme there is very little that has access to conductors that this doesn't apply to. How many times when troubleshooting does one take voltage readings at locations that don't have 110.26 working space? Is somewhat unavoidable with a lot of applications.

I don't disagree with your scenario nor your interpretation. What I was stating at the time was that a fused disconnect or a nonfused disconnect have the same function and merely having fuses shouldn't raise a disconnect to the level of 110.26
 

MAC702

Senior Member
Location
Clark County, NV
To use examples I see every day in an attic crawl space, where I'm often on my knees or sitting down:

1. single-pole snap switch used as disconnect to furnace.
2. cord-and-plug connected furnace.
3. NF pull-out (or breaker-style (no OCP)) disco.
4. Fused (up to 60A) pull-out (or breaker) disco.

In the real world, I see them all, in the exact same conditions. I'll let the engineers figure it out.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
An example that has been brought up here many times in the past - Air conditioner not working, HVAC tech gets called, first thing he does is check for voltage at the disconnect. No voltage? tell them to get an electrician.

How does that not fit into "likely to require examination, adjustment, servicing, or maintenance while energized" mentioned in 110.26?

Since NEC is pretty vague in not telling us what is "likely" to have those requirements - if taken to an extreme there is very little that has access to conductors that this doesn't apply to. How many times when troubleshooting does one take voltage readings at locations that don't have 110.26 working space? Is somewhat unavoidable with a lot of applications.

Here in NJ the State (something that I disagree with) has ruled that the 30" and 36" clearances do not apply to AC unit disconnects.
 
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