Backward switch

[Gaffen99]

I have encountered a lot of roof top A/C units that are factory wired with the load wires connected to the L1,L2, &L3 terminals of the factory disconnect. This was brought to the manufactures attention and they replied that the switch will work both ways. That wasn't really my point, more that if the switch is in the off position the what should be load side is actually still live. At 480 volts, I see a problem with this. Is there a code article I can use for my argument, as to the proper wiring of a switch?

 

[ceb58]

I have encountered a lot of roof top A/C units that are factory wired with the load wires connected to the L1,L2, &L3 terminals of the factory disconnect. This was brought to the manufactures attention and they replied that the switch will work both ways. That wasn't really my point, more that if the switch is in the off position the what should be load side is actually still live. At 480 volts, I see a problem with this. Is there a code article I can use for my argument, as to the proper wiring of a switch?

If it were wired the other way it still would be live. Unless the switch is marked line-load then ether way will work.

 

[480sparky]

........... Is there a code article I can use for my argument, as to the proper wiring of a switch?

110.3(B) perhaps.

 

[Gaffen99]

The switch is marked L1, L2, L3 and T1, T2, and T3. I just think that if the swicth is in the off position that T1, T2, and T3 should be de-energized. This is not the case if you wire the switch backwards. I think it is a safety issue.

 

[hillbilly1]

Be careful in manufactured panel/contactor assemblys too, I've seen them feed the line in at the bottom and load out of the top on large contactors. I don't think there is any code issue preventing them from doing this as it is a manufactured assembly. It can screw you up troubleshooting though.

 

[kwired]

Be careful in manufactured panel/contactor assemblys too, I've seen them feed the line in at the bottom and load out of the top on large contactors. I don't think there is any code issue preventing them from doing this as it is a manufactured assembly. It can screw you up troubleshooting though.

As with a switch or circuit breaker same is true with a contactor, if it is not marked "Line" and "Load" then you can use either end for either purpose. Fused switches must disconnect the fuse so you can remove the fuses deenergized. Most other devices will not care which side is supply and load and will work the same either way.

Many people think line side has to be on top. NEC does not require this. It is common for that to be the case many times. When a piece of equipment is fed from the bottom why should you have to bring conductors around to the top of the device in question, and then sometimes feed the load conductors out the top. If you are dealing with large conductors it is easier to land the supply on the bottom and the load on the top in these cases.

We then have all those that complian about codes being made to protect those who are not necessarily "qualified persons". A qualified person will have no trouble figuring out which side is the supply and which side is the load - that is what your meter is for - and you should be making sure there is no voltage before performing tasks that may subject you to contact with energized parts anyway.

 

[jim dungar]

L1, L2, L3 and T1, T2, and T3 markings are not the same as the required Line and Load wording.

To assume the bottom of a switch is always de-energized when the switch is off is a dangerous act.

 

[kwired]

110.3(B) perhaps.

If the switch is part of listed equipment 110.3(B) does not apply to this particular switch in the listed equipment.

 

[kwired]

L1, L2, L3 and T1, T2, and T3 markings are not the same as the required Line and Load wording.

To assume the bottom of a switch is always de-energized when the switch is off is a dangerous act.

And a switch installed horizontally can with no question be fed from either side unless marked LINE and LOAD.

 

[macmikeman]

If somebody ever was left laying dead at the front of one of those units where the terminals were wired up with the line side reversed with the load side, marked or unmarked, line and load, or t1,t2,t3, L1,L2,L3, etc, the attorneys would have a field day with it, proper lock out tag out and other safety issues be damned. The AC unit maker is putting something out in the wind with this.

 

[hurk27]

We had a case a few years ago, where the manufacture turned the contactor up side down and T1, T2, T3, was one top, and our guy didn't catch it, the problem wasn't that it was on top, the problem was they also had the compressor connected to these terminals, but had the condenser fan connected to the bottom L1, L3 so if our guy would had landed the feed on the bottom the fan would have ran as soon as power was applied, but instead as it was done the compressor would run as soon as power was applied, and after three of the HVAC guys tried to figure it out, and two of our guys, the HVAC boss, started accusing our guys of burning something up as to why it was doing this, so I was called and found the problem immediately and showed them it was a manufacture mistake, the bad thing was that all six units was wired the same way. we wound up back charging the HVAC company and they back charged the manufacture for the trouble shooting.

 

[kwired]

If somebody ever was left laying dead at the front of one of those units where the terminals were wired up with the line side reversed with the load side, marked or unmarked, line and load, or t1,t2,t3, L1,L2,L3, etc, the attorneys would have a field day with it, proper lock out tag out and other safety issues be damned. The AC unit maker is putting something out in the wind with this.

The attorneys win $$$ even if they lose their case.

The service person is responsible for turning off and checking for voltage. If he has a need to do some testing while energized he is responsible to use proper protective equipment. The dead service person is always the loser, and the attorneys always the winner, anyone else involved is just somewhere in between.

 

[jim dungar]

If somebody ever was left laying dead at the front of one of those units where the terminals were wired up with the line side reversed with the load side, marked or unmarked, line and load, or t1,t2,t3, L1,L2,L3, etc, the attorneys would have a field day with it, proper lock out tag out and other safety issues be damned. The AC unit maker is putting something out in the wind with this.

There was a time, for sure in the 80's, when standard size 1 GE motor control center buckets were wired with the line on the bottom and the load (starter) on the top. There are plenty of instances where equipment has been built in this manner (i.e. bottom entry), it would be hard to prove 'poor design' on this reason alone.

 

[hillbilly1]

Many people think line side has to be on top. NEC does not require this. It is common for that to be the case many times. When a piece of equipment is fed from the bottom why should you have to bring conductors around to the top of the device in question, and then sometimes feed the load conductors out the top. If you are dealing with large conductors it is easier to land the supply on the bottom and the load on the top in these cases.

I'm not saying it cannot be done, I'm just saying to be carefull! Our industry standard is to put the line at top when possible, when you open a big contactor cabinet your first instinct is that line is at the top. Manufactures put it where it is most convienent. If you were wiring a cabinet full of small contactors, you would normally put line at top. To save 2" of wire, manufactures could possibly put it on the bottom. Testing will always show which way it is wired though.

 

[Gaffen99]

Does L1, L2, & L3 mean line to anyone? Or am I mistaken.

 

[kwired]

I'm not saying it cannot be done, I'm just saying to be carefull! Our industry standard is to put the line at top when possible, when you open a big contactor cabinet your first instinct is that line is at the top. Manufactures put it where it is most convienent. If you were wiring a cabinet full of small contactors, you would normally put line at top. To save 2" of wire, manufactures could possibly put it on the bottom. Testing will always show which way it is wired though.

Can you tell us where that standard may be published? Common practice, yes. Code requirement, no. How about the residential grade AC units that use a 2 pole contactor that only actually has a contact in one pole and the other side is just a buss from line to load side - I can't tell you how many times I have run into HVAC guys or others that can't understand why they still have voltage when the contactor coil is not energized.

Does L1, L2, & L3 mean line to anyone? Or am I mistaken.

Usually, how about the input leads on a motor often labeled T1,T2,T3...?

 

[hillbilly1]

Can you tell us where that standard may be published? Common practice, yes. Code requirement, no.

I didn't see anywhere in my post that I said it was a written standard or code requirement.

 

[jwelectric]

404.6

(C) Connection of Switches.​

​

​

​

​

Single-throw knife switches
and switches with butt contacts shall be connected such that
their blades are de-energized when the switch is in the open
position. Bolted pressure contact switches shall have barriers
that prevent inadvertent contact with energized blades.
Single-throw knife switches, bolted pressure contact
switches, molded case switches, switches with butt contacts,
and circuit breakers used as switches shall be connected so
that the terminals supplying the load are de-energized when​

the switch is in the open position.

 

[iwire]

404.6

(C) Connection of Switches.​

​

​

​

​

Single-throw knife switches
and switches with butt contacts shall be connected such that
their blades are de-energized when the switch is in the open
position. Bolted pressure contact switches shall have barriers
that prevent inadvertent contact with energized blades.
Single-throw knife switches, bolted pressure contact
switches, molded case switches, switches with butt contacts,
and circuit breakers used as switches shall be connected so
that the terminals supplying the load are de-energized when​

the switch is in the open position.

Does not apply to the internal parts of listed equipment does it?

As the poster stated, it is a factory installed disconnect.

 

[jim dungar]

404.6

(C) Connection of Switches.

Single-throw knife switches

and switches with butt contacts shall be connected such that
their blades are de-energized when the switch is in the open
position. Bolted pressure contact switches shall have barriers
that prevent inadvertent contact with energized blades.
Single-throw knife switches, bolted pressure contact
switches, molded case switches, switches with butt contacts,
and circuit breakers used as switches shall be connected so
that the terminals supplying the load are de-energized when​

the switch is in the open position.
​

There is nothing in this section about 'top or bottom' feed.
​