2 or more switches of different voltages in the same metal box.

[tommy]

Benaround Thanks for that art. Makes sense

 

[Smart $]

Explain on how I can check as far as lead check Prmary (a) to Secondary (a) then Primary(a) to Secondary (b) and so on for each phases

Yep! Measure any one primary to each secondary, in succession of course: H1 to X1, H1 to X2, then H1 to X3. You should get three different voltages, close to the three in the diagram. Same if you measure H2 or H3 to each X in succession, but the voltages won't be in the same order.

 

[tommy]

Thanks Smart$ I'll check again

 

[celtic]

celtic,

250.146(A) , only refers to receptacles, in your 1900 box with Mulbury

cover, if cover is not listed for grounding,then a jumper would be required.

IMO a switch would not. I did mention that adding one would not hurt.

Check 404.9(B)




To simply say:

When useing metal boxes you do not have to ground to the switch,the 6/32 screws are allowed to ground the yoke. On the other hand, it will do no harm.

...is misinforming - 404.9(B) indicates when it is required and when it is not.

Also, the discussion at the time was talking about 'flush' type boxes and

barriers.

I never saw the word "flush" or even "surface" mentioned until now...

 

[benaround]

Celtic,

You are correct,I was a little to quick on the draw that time. I've never

used a 1900 with a barrier,my bad.

 

[celtic]

No big deal benaround

 

[dcooper]

barrier

barrier

Tommy I was always taught that you don't have to put a barrier between 120 and 277. just 277 and 277. i did most of my apprenticeship building schools. so there are usually multiple systems in the building.

 

[roger]

Dcooper, welcome to the forum. Now I must ask, what is your point? It has been shown in this thread that 120 and 277 volt switches can have above 300 volts between them and a barrier is needed per code.

Roger

 

[celtic]

Tommy I was always taught that you don't have to put a barrier between 120 and 277. just 277 and 277. i did most of my apprenticeship building schools. so there are usually multiple systems in the building.

Having multiple sources/supply in a junction box or raceway is not the issue.

The issue is when you have the potential for more than 300v between adjacent devices ~ 404.8(B)