Supply to shipping container

[jibjob]

Hi all,

A local restaurant has been having problems with intermittent tripping of RCBO supplying a metal shipping container which they use for storing frozen food etc. I've identified the fault which I won't go into as it's not really relevant.
The system is TT, & currently there is 4mm SWA running to the container from the CU protected by a single pole 32a RCBO with a DP main switch isolator up front (as opposed to a time delay RCD).
The SWA emerges from the ground about 6" from the edge of container, goes underneath it & appears at the rear of the container in 2.5mm T&E (don't ask) which then passes through the container by means of what looks like some sort of ventilation duct to a metal clad CU which bizzarely has been mounted upside down.
Two circuits to lights & sockets, T&E cable haphazardly draped around the container, no main bonding, all n all a total mess.
I've proposed to break into the exising SWA where it emerges from the ground, not sure whether I'll joint it under or overground yet, it will depend on how much cable I have to play with & continue to CU in SWA around the outside of the container to CU. Will install main bonding & rewire the container in PVC conduit & metal clad accessories.
I was thinking that I should also sink a spike local to the container (container is approx 25m from main building) & stick a 100mA time delay RCD on the front of the main board in main building. All circuits on main board have 30mA protection by means of single pole RCBOs.
Any thoughts would be most appreciated

Cheers

 

[shanky887614]

Hi all,

A local restaurant has been having problems with intermittent tripping of RCBO supplying a metal shipping container which they use for storing frozen food etc. I've identified the fault which I won't go into as it's not really relevant.
The system is TT, & currently there is 4mm SWA running to the container from the CU protected by a single pole 32a RCBO with a DP main switch isolator up front (as opposed to a time delay RCD).
The SWA emerges from the ground about 6" from the edge of container, goes underneath it & appears at the rear of the container in 2.5mm T&E (don't ask) which then passes through the container by means of what looks like some sort of ventilation duct to a metal clad CU which bizzarely has been mounted upside down.
Two circuits to lights & sockets, T&E cable haphazardly draped around the container, no main bonding, all n all a total mess.
I've proposed to break into the exising SWA where it emerges from the ground, not sure whether I'll joint it under or overground yet, it will depend on how much cable I have to play with & continue to CU in SWA around the outside of the container to CU. Will install main bonding & rewire the container in PVC conduit & metal clad accessories.
I was thinking that I should also sink a spike local to the container (container is approx 25m from main building) & stick a 100mA time delay RCD on the front of the main board in main building. All circuits on main board have 30mA protection by means of single pole RCBOs.
Any thoughts would be most appreciated

Cheers

Dont need rcd/rcbo upfront for swa.

Get rid and have one inside unit

 

[Plonker 3]

Dont need rcd/rcbo upfront for swa.

Get rid and have one inside unit

Yrs it it does, it's a TT

 

[shanky887614]

Yrs it it does, it's a TT

Thats a time delayed. And in his case its off an rcbo


At the moment we are talking about a supply to a sub board.

The upfront device for this is the breaker that feeds this db which at the moment is an rcbo.

 

[Plonker 3]

It sounds a complete mess regardless, no RCD time delayed main switch, all circuits fed from SP RCBOs. The SWA still feeding said container still needs to be RCD/RCBO protected. With all,sub circuits in the container then just needing to be fed via a normal main switch and MCBs.

 

[jibjob]

It is a complete mess & in some ways I wish I'd never laid eyes on it. However, with a bit of work it can be sorted. My main concern is whether to put in another spike adjacent to container going back to sub board or whether to rely on the existing spike (Ra was 75ohms at main board).