breaker lock for dishwasher

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Old 07-21-08, 08:01 PM
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breaker lock for dishwasher

I put in a new line to a new dishwasher. 20 amp service. The dishwasher was installed by the people who did the kitchen cabinets and sink-faucet. I think they used a plug provided so it is not direct/hardwired. The inspector asked and I was not sure. He said that I had to put a lock on the breaker. That is fine, but I would like to undertstand what is going on.

1. My understanding is that if the DW is plugged into the outlet behind it, this lock is not needed. Is that correct and why? But I also understand that the lock is still permisable and cannot hurt to have in either wiring configuration. yes/no?

2. How does the lock work? I imagine it lets you turn the breaker off or allows it to trip off, but not be simply switched back on.

3. My understanding of the purpose of the lock is so that if the breaker internally trips, a person in the house cannot simply turn on the circuit to restore power. This is important because if the breaker trips the circuit is not simply overloaded by too many "in use" devices. The circuit only services the dishwasher and has plenty of power to supply the machine acequately. If the circuit trips, then something is wrong that must be fixed before power is re-supplied. Is this the correct theory? If so, what is the issue being worried about esspecially--or exclusively-regarding the hardwiring method?

4. Furthermore, my attention has been drawn to nec 422.32. It appears to me that because the dishwasher does not have an "insight disconecting means," the breaker lock is an alternative means to do whatever the insight disconecting means would do. An answer to 2 would explain this "do whatever."


Thank you
 
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Old 07-22-08, 06:32 AM
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The purpose of the breaker lock is to ensure that no one restores power to a dishwasher that someone could be working on. A repairperson would install a padlock through the breaker lockout and keep the key in their pocket. When they are finished the padlock is removed. This is designed so that someone unaware that working is being performed and restores power to the dishwasher and does not electrocute the worker.

The plug can serve as the disconnect if the motor is small enough and because to restore power most likely you would need to step over the worker.
 
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Old 07-22-08, 06:50 AM
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Ha. The last time I had a DW installed, the "installer" didn't even shut off the power.
 
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Old 07-22-08, 07:00 AM
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I understand the logic here but why would this be different then any other circuit? Someone could restore a breaker on any circuit you were working on, not just a dishwasher. With this logic you would need a lockout on anything permanently wired, like a stove? But why would they be more likely to be falsely re-energized then any other circuit?

Just wondering....
 
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Old 07-22-08, 07:30 AM
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Originally Posted by dsc3507 View Post
I understand the logic here but why would this be different then any other circuit? Someone could restore a breaker on any circuit you were working on, not just a dishwasher. With this logic you would need a lockout on anything permanently wired, like a stove? But why would they be more likely to be falsely re-energized then any other circuit?

Just wondering....
Just wait. They change that thing every three years. They'll get to LOTO for everythign in a house eventually.
 
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Old 07-22-08, 07:34 AM
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I can't see the need either, but the Code is the Code and is meant to be followed. Even if I do not see the need I need to comply with the rules.

I had a builders grade DW in my first houser that lasted 15 years without problems. Most people, I would hope, would remember that the repair person was in the kitchen working on the DW and not flip the breaker on. Given the fact the typically the DW is a dedicated circuit turning it off would not affect anything else in the house.

If you went to run the dishwasher and it did not run would you not see the DW out of place and remember that repairs where under way?
 
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Old 07-22-08, 09:19 AM
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The NEC has required disconnects on motors over a certain size forever. The rule has always been that the disconnect must be in line-of-sight and less than 50 feet from the motor. The rule has been tweaked several times over the years. At one time the rule allowed the disconnect to be out of the line of sight if it could be "locked" yet it did not specify what "locked" meant. Now locked means with a padlock that only the worker (and maybe his supervisor) has the key.

This is also driven by workplace safety rules or OSHA. Sometimes the interpretation of the requirements goes really overboard. The stupidest I ever saw (in my opinion, of course) was a cooling tower installation that had a NEMA 3R panel containing the motor starters and circuit breakers for the fan motors located immediately adjacent and within the line of sight rules. The circuit breakers all had "approved" locking devices (could be locked on the off position with a padlock) yet the design engineer also specified safety lock out switches. The switches were located on the side of the cooling tower AWAY from the fan motors, out of sight of both the fan motors and the electrical source panel. There was no need for the safety switches and it was a colossal waste of money.
 
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Old 07-22-08, 07:16 PM
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Originally Posted by jam1jam1 View Post
I put in a new line to a new dishwasher. 20 amp service. The dishwasher was installed by the people who did the kitchen cabinets and sink-faucet. I think they used a plug provided so it is not direct/hardwired. The inspector asked and I was not sure. He said that I had to put a lock on the breaker. That is fine, but I would like to undertstand what is going on.

Are you saying the receptacle for the dishwasher is not accessible?


Here are the exact rules for an appliance motor,

422.32 Disconnecting Means for a Motor-Driven Appliance, if a switch or circuit breaker serves as the disconnecting means, it shall be located within sight.

Here are the exceptions:

422.33 Cord & Plug Connected Appliances, An accessible plug and receptacle shall be permitted to serve as the disconnection means.

422.34 Unit Switch, A unit switch that disconnects all ungrounded conductors shall be permitted as the disconnect. (very unlikely with newer dishwashers)

Motor disconnects are for one thing, and one thing only, safety for someone working on the appliance. Accidents happen and this is the end result, safety codes for appliances...
 
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