NEC 2008 Test Question. I have Searched all weekend to no avail.

[twistr2002]

What is the Maximum Voltage for an Isolated Transformer in a hospital's Anesthesiology Unit?

any help locating this in the 2008 NEC would be greatly appreciated, it has been bugging the heck out of me since thursday when I failed my test by 1 question. I spent way too much time looking for this.

Thanks in advance

Matt

 

[BSSTG]

Greetings

Tough one. How about 517.64(a)? 10 volts

BS

 

[north star]

= = =

See if Article 517.160(2), [ `08 NEC ] is the one for you......Max. 600 volts,

"if" designed & installed as a Hazardous location [ RE: Article 517.61(3) ].

The designation of "flammable" anesthetizing or "non-flammable" anesthetizing

room must be [ formally ] assigned so that construction methods can be installed.

= = =

 

[twistr2002]

north star

thats the answer i gave too. but they marked it incorrect. my only thought was that there was something reffering to the anesthetizing location that i was missing.

bsstg that was my answer off the top of my head but i could not see how it was refering to an isolated transformer

 

[codeworks]

thanks for the heads up! if it's 600 volts, it has to be above the class 1, div 1 location by a minimumn of 5 feet , correct ?

 

[north star]

=

codeworks,

Correct!

twistr2002,

The question may have been referring to "where" in the anesthetizing room,

...either below the 5 ft. threshhold, or above it!

=

 

[twistr2002]

That makes sense. i hate how they word the test questions just to confuse. hopefully this time I pass it. i am going again on thursday this time for both the plan review and commercial electrical inspector

 

[michaelj]

1200volts

517.61(A) (2)Design and Installation. Where an isolated power system

is utilized, the isolated power equipment shall be listed

as isolated power equipment, and the isolated power system

shall be designed and installed in accordance with 517.160.

517.160(A)(2) Circuit Characteristics. Circuits supplying primaries of

isolating transformers shall operate at not more than 600 volts

between conductors and shall be provided with proper overcurrent

protection. The secondary voltage of such transformers

shall not exceed 600 volts between conductors of each circuit.

 

[north star]

= = = >

twistr2002,

Good luck on your upcoming tests!.....FWIW, I would read & re-read

Article 517.60 for some clarity and familiarity......I have to read &

read & read & read, and sometimes, it still doesn't make any sense

to me.

< = = =

 

[michaelj]

sorry, should be 600 volts

 

[twistr2002]

thats the nec though. i am used to reading everything in that book about 5 times before it makes sense, and thats after jumping from section to section and forgeting where i started in the first place. i guess its just the nature of the beast, personally i like the way that icc sets up their book. much easier to navigate, at least for me any way.

 

[north star]

& &

twistr2002,

Do you remember what the choices were?

& &

 

[Dennis]

Well if 600v is not the answer then I don't know what it is. I wonder if they were thinking VA based on the fpn below. Do you know what the answer was? Fpn are not code either just a heads up so not sure.

(6) Wire-Pulling Compounds. Wire-pulling compounds that increase the dielectric constant shall not be used on the secondary conductors of the isolated power supply.FPN No. 1: It is desirable to limit the size of the isolation transformer to 10 kVA or less and to use conductor insulation with low leakage to meet impedance requirements.

FPN No. 2: Minimizing the length of branch-circuit conductors and using conductor insulations with a dielectric constant less than 3.5 and insulation resistance constant greater than 6100 megohm-meters (20,000 megohm-feet) at 16°C (60°F) reduces leakage from line to ground, reducing the hazard current.

 

[north star]

( * )

Dennis,

Thanks for the input!......That's what I would have selected on the

test also!

twistr2002,

"If" it were me, I would follow-up with ICC and ask them for the

correct answer and applicable NEC Article.......Missing the test

by only 1 question is too close not to ask for some clarity.

Besides, if you DID answer this one question correctly, you

wouldn't have to take the test again......Yeah, the Commercial

Electrical Inspector exam is a tough one!

FWIW, on another electrical forum, they are also saying

" 600 volts max. ".

( * )

 

[twistr2002]

120v 240v 480v and 600v.

the way that i determined this was my problem question. on the test report it told me there was 1 question on transformers on the test, and that i got it wrong.

it was at a prometric testing center so its not actually an icc test just an equivalent.

 

[north star]

> > >

twistr2002,

Can you go back to "Prometric " and ask for clarity, or even to ICC,

"if" this is one of their contracted testing centers?.......If not ICC,

is there someone that you can actually ask?

< < <

 

[BSSTG]

I was obviously wrong with the 10 volts not knowing the given answers. Yep, with those answers I would have put down 600 and wouldn't even look it up unless I had plenty of time. I have taken about a dozen ICC tests and on several tests that I did pass I know that there were some answers that were incorrect, as in the correct answer wasn't an option. However, I when I took the commercial elect. I found it to be a relatively easy test with most answers pretty straightforward. Just the luck of the draw I guess.

good luck Thurs.! You're a braver man than I.

BS

 

[Mule]

If you only need one question to get your certification what about the other questions you missed. Maybe you got that "one" question you are referring too right and it was another question in that category you failed to answer correctly? Just thinking.......

 

[twistr2002]

thats what my dad was saying too mule. he said maybe they classified that question as health care facilities. i dont think there was another transformer question though. Prometric said that i did get that question right. but they could not elaborate on the ones that i missed. I will do better thursday