disconnecting means quest?

[wireman1]

article 422.31(a)states that motors rated at not over 300volt-ampers or 1/8 hp the branch circuit overcurrent device can service as the disconnectingmeans.it does not mention it has to be in sight of the appliance. yet 422 (b)appliances rated over 300 volt-ampers or 1/8 hp the switch or circuit braker must be within sight from the appliance or is caple of being locked out in the open position . there is a new paragraph in the 2005 code starting with the provisionfor lockingor adding a lock etc . this mainly applies to dishwashers wich do not have a on or off switch.ques? what is the reason in (a) becuse the motor is not over 300 volt _ ampers or 1/8 hp it does not have to be in sight or locked in the open position .yet in (b) because it is over the 300 va and over the 1/8 hp it has to be in sight or locked out. the motors both operate at the same voltage 120 volts .what is the main main difference that makes the requirments different between (a) and (b)

 

[George Stolz]

what is the main main difference that makes the requirments different between (a) and (b)

I don't know. I just looked at the ROP from the 2005 that generated the change:

17-24 Log #1690 NEC-P17 (422-31(B))
Final Action: Accept
Submitter: James T. Dollard, Jr., IBEW Local 98

Recommendation:
Revise section 422.31(B) with new text as follows:
422.31(B) Appliances Rated Over 300 Volt-Amperes or 1/8 Horsepower. For permanently connected appliances rated over 300 volt-amperes or 1/8 hp, the branch-circuit switch or circuit breaker shall be permitted to serve as the disconnecting means where the switch or circuit breaker is within sight from the appliance or is capable of being locked in the open position. The provision for locking or adding a lock to the disconnecting means shall be permanently installed on or at the switch or circuit breaker used as the disconnecting means.
FPN: For appliances employing unit switches, see 422.34.

Substantiation:
The problem with the present wording of this section is that the disconnect in many appliance applications is a circuit breaker in a panelboard or a switch that is not made with permanent provisions for locking the circuit breaker or switch in the open position. This clearly does not meet the requirements of 422-31(B). This section states "capable of being locked in the open position." With lock in hand an installer/maintainer can apply it and work safely. This language does not include "through the use of a device which will permit
a lock to be utilized."

However, the onset of circuit breaker & toggle switch locking devices have given the impression that any circuit breaker or switch is capable of being locked in the open position. Existing circuit breaker/toggle switch lockout devices are not permitted by OSHA.

OSHA requires that they be approved (listed by National Recognized Testing Laboratory). None are listed. If these devices were recognized by OSHA then the NEC would expect that every installer/maintainers in the United States and Internationally would each carry dozens of different accessory devices to safely lockout motor power sources. This is not practical. Permanent provisions for making circuit breakers and switches capable of being locked in the open position are readily available from manufacturers today. This proposal does not represent a large increase in the cost of an installation but will result in a dramatic increase in safety. Where appliances are involved we know that regular maintenance will take place, we must ensure that only a lock is needed by an installer/maintainer to work safely. The practical safeguarding of persons from electrical hazards as detailed in the scope of the NEC must not be permitted to hinge on whether or not an installer just happens to have enough different types of devices and hopefully one that that happens to fit the circuit breaker or switch in an installation.

Where appliances are involved we know that regular maintenance will take place, we must ensure that only a lock is needed by an installer/maintainer to work safely. Note that this language was accepted by CMP-11 and is a present requirement, in the 2002 NEC, when a circuit breaker or switch is used as a disconnecting means not within sight of a motor. The same level of safety is needed for these disconnecting means for larger appliances.

Panel Meeting Action: Accept
Number Eligible to Vote: 12
Affirmative: 12 Ballot Results:

James Dollard believes this is because larger appliances are more prone to servicing. That could be the reasoning for the requirement, I don't know.

 

[dcspector]

George, Interesting. I had a call regarding water heater disconnects in a hi rise condo. Each unit has a typical 40 gal. 4.5 kw water heater in it's mech. room and the unit panels (sub panels with mains) are not within sight of the appliance (the other end of each unit in the Den) 422.31(B) would be the correct call. Thoughts?.....Install lock outs on the 2p 30amp breaker? Also, 422.31 when calculating the 1/8 th HP can one use the 746 watts per HP? to use this article 422.31(B) ?

"Needy aren't I" ?

 

[George Stolz]

422.31(B) would be the correct call. Thoughts?.....Install lock outs on the 2p 30amp breaker?

Agreed.

Also, 422.31 when calculating the 1/8 th HP can one use the 746 watts per HP? to use this article 422.31(B) ?

I think that HP or VA is determined by the rating of the appliance. If the rating is in VA, use the 300 VA number. If it's in HP, use the HP number.

 

[dcspector]

Thanks George.

 

[Pierre C Belarge]

George

Not bad for an "all-around Hack" :wink:

 

[George Stolz]

I'm answering this question on the thread, as I'd feel more comfortable with the scrutiny of the forum on my answer. Sorry for the delay, that time of year.

The question I would like answered is that Article 422.31(a) states that motors rated 300 VA or 1/8 horsepower or less do not need another disconnect or a lock out for the breaker. If the breaker supplies a dishwasher not in sight does this still hold true? Some inspectors are now saying that you must use the new paragraph in 422.31(b) to comply with code. What are your thoughts on this?

There are two aspects to this, IMO. A dishwasher is almost guaranteed to draw more than 2.5 amps, and it also contains a motor.

Since it contains a motor, then we must look at the motor and see if it is greater than 1/8 HP, as outlined in 422.32. If 422.32 requires the disconnecting means, it's also required to be within sight. (With a nod of the head to Iwire for recently reminding me of this section. )

I doubt most residential dishwashers have a motor larger than 1/8 HP.

If the motor is less than 1/8 HP, then we turn back to 422.31. Is the dishwasher rated at over 300 VA? Looking at my little dishwasher behind me, the tag reads

Motor: 5.2 Amps
Heater: 4.4 Amps
Total Current: 8.6 Amps​

Since it draws more than 2.5A @ 120V, it's too big for 422.31(A) to apply to it.​

With any non-motor permanently-connected appliance, if it is less than 300 VA or 1/8 HP, then you are permitted to assume that the person going to service the equipment will have a breaker lock of their own to lock out the equipment. Greater than that, you assume all they have is a padlock. At least, that's my read on this section.​

Hope that helps.​