# Safe Use Of Electricty Under Water Flashcards

1
Q

What time frame must a protected circuit be?

A

20 milliseconds

30mA

2
Q

Irrespective of voltage,( 50v +) how many ohms is a typical worst case figure for limb to limb contact on a diver?

A

500 ohms

3
Q

If the voltage was 50v or less, what’s is the max amount of ohms considered safe for a diver?

A

750 ohms

4
Q

What voltage is considered to be classed as high voltage?

A) 750 V

B) 1000V

C) 1500V

D) 2000V

A

B) 1000V

5
Q

What voltage is considered to be classed as a low voltage?

A) any voltage up to 50V

B) any voltage up to 100v

C) any voltage up to 150v

A

A) any voltage up to 50V

6
Q

What are the voltage ranges, to be considered for medium voltage?

A

50v-1000v

7
Q

How many volts would be considered to be classed as ultra high?

A

30,000v

8
Q

In diving, what is considered to be a safe range of frequency for a diver?

A) 40-50 Hz

B) 50-60 Hz

C) 50-70 Hz

D) 40-100 Hz

A

B) 50-60Hz

9
Q

What is the maximum voltage for a diver on a dc circuit without a trip device?

A

30v

10
Q

What is the normal voltage for a diver on a dc circuit without a trip device?

A

24 volts

11
Q

What is the maximum voltage for a diver on an ac circuit without a trip device?

A

7.5 volts

12
Q

What is the normal voltage for a diver on an ac circuit without a trip device?

A

6 volts

13
Q

What is the maximum voltage for a diver on a dc circuit with a trip device?

A

285v

14
Q

What is the normal voltage for a diver on a dc circuit with a trip device?

A

250 Volts

15
Q

What is the maximum voltage for a diver on an ac circuit with a trip device?

A

250 volts

16
Q

What is the normal voltage for a diver on an ac circuit with a trip device?

A

220 volts

17
Q

A diver is using a welding/cutting tool under water. Is this tool the positive or negative side of the circuit?

A

Negative

Positive to be clamped to the cut/welded part of the metal.

18
Q

A welding cable should comprise of what?

A

Two fully-insulated conductors

19
Q

What is the typical instrument voltage inside hyperbaric chamber?

A

220 volts ac protected by an RCD

20
Q

What voltage is currently used inside a diving bell?

A

24 volt dc no active protection

21
Q

What are the external bell lights circuit set up?

A

220 v ac on an RCD protection

22
Q

What voltage circuit is used for internal lights on a welding habitat?

A

24v dc

23
Q

Preheat for a habitat runs on what voltage?

A

100Volts

24
Q

What percentage of ripple affect will dc be treated as ac?

A

5%