Nut Blaster
Marine/Ocean
- Oct 3, 2024
- 1
Just looking for some opinions in reference to ABS MVR Part 4, Chapter 8, Section 2, 7.3.1
Basically my question is in regards to local grounding of EGC's on a 480V system with HRG. It seems to specifically prohibit this.
An example is running a 3C (no grounding conductor) cable to a motor from an MCC and then using a bonding jumper from the frame of the motor directly to hull steel(typically some steel structure immediately adjacent to the motor)
We have an NRG sized for 5 amps and to me they should be running a 4C cable, landing the EGC on the ground lug in the peckerhead and the other end to the ground bus in the MCC. If there is a fault it will be 5A(potentially) flowing which is way more than 30mA.
Anybody have any opinions or other interpretations?
It states:
ABS MVR part 4, Chapter 8, Section 2
7.3 Hull Return Systems
7.3.1 General
A hull return system is not to be used, with the exception as stated below:
● Impressed current cathodic protection systems;
● Limited locally earthed system, provided that any possible resulting current does not flow
through any hazardous locations;
● Insulation level monitoring devices, provided the circulation current does not exceed 30 mA under all possible conditions.
● Current-carrying parts with potential to earth are to be protected against accidental contact.
Basically my question is in regards to local grounding of EGC's on a 480V system with HRG. It seems to specifically prohibit this.
An example is running a 3C (no grounding conductor) cable to a motor from an MCC and then using a bonding jumper from the frame of the motor directly to hull steel(typically some steel structure immediately adjacent to the motor)
We have an NRG sized for 5 amps and to me they should be running a 4C cable, landing the EGC on the ground lug in the peckerhead and the other end to the ground bus in the MCC. If there is a fault it will be 5A(potentially) flowing which is way more than 30mA.
Anybody have any opinions or other interpretations?
It states:
ABS MVR part 4, Chapter 8, Section 2
7.3 Hull Return Systems
7.3.1 General
A hull return system is not to be used, with the exception as stated below:
● Impressed current cathodic protection systems;
● Limited locally earthed system, provided that any possible resulting current does not flow
through any hazardous locations;
● Insulation level monitoring devices, provided the circulation current does not exceed 30 mA under all possible conditions.
● Current-carrying parts with potential to earth are to be protected against accidental contact.
