Disconnection time 120 volts Uo vs 150 volts Uo

[ProMbrooke]

Is there any real danger in using a 0.8 seconds as disconnection time for 150 volts line to ground? Or would a sweet spot at 0.7 seconds work? Call me cheap but I don't want to use 0.4 seconds unless I really have to.
 

 

[Andy™]

well table 41.1 requires 0.4 for TN or 0.2 for TT (both AC), so if you want to deviate then you would have to justify that and mark it int he deviations box on your EIC/MWC

 

[Tony S]

@ProMbrooke is American, test certificates don't exist.

 

[Andy™]

@ProMbrooke is American, test certificates don't exist.

neither does any form of testing

 

[kerching]

neither does any form of testing

Switch on

listen

nothing?

jog on

bang?

get someone in

jog on

 

[ProMbrooke]

But is there really any danger Andy? I don't see a huge increase in danger between 120 and 150 volts line to ground.

Switch on

listen

nothing?

jog on

bang?

get someone in

jog on

Lets stick to electrical theory here please

 

[kerching]

But is there really any danger Andy? I don't see a huge increase in danger between 120 and 150 volts line to ground.

Lets stick to electrical theory here please

Oh I think you would be unpleasantly surprised at the number of people who subscribe to the aforementioned testing procedure 

 

[ProMbrooke]

Perhaps. But I more interested in the theory.

 

[binky]

OK, in the UK on building sites we use a lot of 110V tools, which gives an RMS value of 50V ish. 50v is regarded as a 'safe' touch voltage, under fault conditions. Clearly the higher the voltage the more risk people are at, but how much difference say an extra 10V adds I don't know. 

 

[ProMbrooke]

True, but remember that in place like the Republic of the Philippines, Saudi Arabia and South America power is distributed line to line. So its 127 to 138 volts line to ground.

 

[binky]

then you need to work with regs pertenent to the country concerned. I'm only familiar with UK regs. 

 

[ProMbrooke]

UK regs are based off of IEC-60364. Same disconnection time is in the IEC. My question is- does a 0.8 second disconnect time really pose any hazard at 150 volts to ground? If so would a 0.65 second timing be ok? 0.4 seems like extra material.

 

[binky]

I'm trying to remeber what the disconnection times were before it all went 0.4?  We suppossedly work on 230V which is roughly 115V to ground and certainly hurts! 

 

[ProMbrooke]

I'd be curious to know. 138 volts is 69 volts to remote earth so I'm not that concerned going over 0.4 seconds.

 

[binky]

it doesn't sound like armeggedon to me 

 

[Andy™]

OK, in the UK on building sites we use a lot of 110V tools, which gives an RMS value of 50V ish. 50v is regarded as a 'safe' touch voltage, under fault conditions. Clearly the higher the voltage the more risk people are at, but how much difference say an extra 10V adds I don't know. 

but 110v site supplies are 55v to earth single phase, 63.5v 3 phase. not his 150v to earth

 

[ProMbrooke]

Neither to me.

 

[binky]

but 110v site supplies are 55v to earth single phase, 63.5v 3 phase. not his 150v to earth

is it 150V or 75V ? 150V will kill.

 

[Andy™]

is it 150V or 75V ? 150V will kill.

150v is the voltag the OP is on about. not sure where it comes from

 

[binky]

150v is the voltag the OP is on about. not sure where it comes from

likewise, sounds like foreign places to me