High Leg Dryer

[hillbilly1]

......................................................................

If the dryer had an internal 240/120v Transformer for the lights and the control power it would be a different story. Then it wouldnt matter if the Wild Leg was used on the primary side of the transformer, but that is not the case.

The lights and controls would not be the only problem, most dryers also use a 120 volt motor to drive the drum, apparently a design issue of some sorts.

 

[LarryFine]

The lights and controls would not be the only problem, most dryers also use a 120 volt motor to drive the drum, apparently a design issue of some sorts.

In every dryer I've seen, everything except the heater element is wired between L1 and N. That's what makes them "universal" as far as 240 vs 208 operation is concerned.

The issue here is that there's no way to be certain that every replacement will be wired with the correct internal conductors on the same lines. There are too many places they could swap.

Then, who says L1 on every dryer will be L1 in the cord or receptacle. And even then, that's assuming (uh-oh) every replacement will be done by someone who knows what's going on.

 

[hillbilly1]

In every dryer I've seen, everything except the heater element is wired between L1 and N. That's what makes them "universal" as far as 240 vs 208 operation is concerned.

I remember now that it was you, or maybe it was someone else had the answer to that question when we hashed this out before!

 

[hardworkingstiff]

A rhetorical question

A rhetorical question

Then, who says L1 on every dryer will be L1 in the cord or receptacle. And even then, that's assuming (uh-oh) every replacement will be done by someone who knows what's going on.

Seriously, would any of us really check to see if a high leg was present if we were changing a cord on a dryer? I don't believe I would.

 

[hillbilly1]

Seriously, would any of us really check to see if a high leg was present if we were changing a cord on a dryer? I don't believe I would.

Probably after the magic smoke was let out.

 

[kwired]

Whether you can justify this install with Code references, or not, I think that the probability of someone who is not qualified or experienced enough to get ahold of this and make a bad situation out of it is too high.

I've already seen enough high leg incidents with non qualified or inexperienced persons to agree with this statement.

Heck, I've seen high leg incidents with qualified persons but inexperienced with systems that have a high leg.

Seriously, would any of us really check to see if a high leg was present if we were changing a cord on a dryer? I don't believe I would.

Just changing a cord or replacing an existing dryer the first try, no.

After burning out the second controller, maybe depends how much suspicion of a voltage problem enters the mind.

After burning out a third controller, definately would be doing some voltage checks.

 

[Wire_nutz]

See Disadvantages

See Disadvantages

The reference and supporting documentation sure would be helpful.

http://en.wikipedia.org/wiki/High_leg_delta

 

[kwired]

The reference and supporting documentation sure would be helpful.

http://en.wikipedia.org/wiki/High_leg_delta

Do you put a lot of faith in a reference that anyone is allowed to edit?

In the disadvantages they state:

Since one phase-to-neutral voltage (phase 'B') is higher than the others, no single phase loads can be connected to this phase

True you can not use it for 120 volt single phase loads, but you can use it for 240 volt single phase loads. The question in this thread is can you use it for 120/240 volt loads if you are careful to not place portions of the load requiring the neutral on the wild leg.

I run into hard wired equipment on the farms quite often that have three phase motors and 120 volt control circuit tapped off the line side of motor controllers. You have to watch where you connect the wild leg here, but is not quite the same thing as a cord and plug connected range or dryer, I would leave the wild leg out of these circuits no matter what - those items are often serviced or replaced by people that have no idea what three phase means and would be totally confused by a conductor that is 208 to ground, which they would not find out until after burning something up.

 

[Wire_nutz]

Answer

Answer

FYI,

I finally received an answer from NEMA and UL.

As most of us already have known this as professional electricians, finding the supporting documentation is the problem.

NEMA & UL stated the 120/250 volt, ?/? 120 volts maximum LINE-TO-Neutral and 250 volts maximum LINE-TO-LINE.

The 208 volts to Neutral does not meet the NEMA standard and the manufactures recommended use of the dryer receptacle.

 

[LarryFine]

- those items are often serviced or replaced by people that have no idea what three phase means and would be totally confused by a conductor that is 208 to ground, which they would not find out until after burning something up.

Unless they understood why the conductor was orange, which it's supposed to be when the neutral is present.