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Cable tray
Posted: Tue Nov 10, 2020 7:41 pm
by DougP
Does it need to be earthed?
Re: Cable tray
Posted: Wed Nov 11, 2020 5:34 am
by gregmcc
for double insulated conductors no, but for good practice yes, the photo is a good example
Re: Cable tray
Posted: Wed Nov 11, 2020 8:41 am
by DougP
gregmcc wrote: ↑Wed Nov 11, 2020 5:34 am
for double insulated conductors no, but for good practice yes, the photo is a good example
That's not going to help the guy on the forklift if he gets off it when the forklift is live though. The cables were only damaged on the forklift side, not the back.
And any electrical worker getting up there to repair, should be isolating it before working on it. With that number of circuits, the only option was isolating the whole building.
Re: Cable tray
Posted: Wed Nov 11, 2020 4:33 pm
by gregmcc
What it comes down to is installing to the conditions, we all know that things like cable tray and switchboards are targets for forklift drivers and it's just a matter of time before they get hit. I have in the past insisted on bollards (which are also a target for the forklift drive) which have proved effective
Re: Cable tray
Posted: Wed Nov 11, 2020 8:07 pm
by t92300
DougP wrote: ↑Wed Nov 11, 2020 8:41 am
That's not going to help the guy on the forklift if he gets off it when the forklift is live though. The cables were only damaged on the forklift side, not the back.
And any electrical worker getting up there to repair, should be isolating it before working on it. With that number of circuits, the only option was isolating the whole building.
The edge of the tray looks damaged by the forklift. The forklift could have been in contact with the tray and live copper at the same time.
The guy on the forklift would have reversed back so that he could inspect the damage wouldn't he? The mast would have been blocking his view of the tray.
Re: Cable tray
Posted: Thu Nov 12, 2020 9:20 am
by AlecK
Earthing the tray would need to be done based on size of largest conductor present.
And even so wouldn't necessarily do any good; as the forklift (or whatever) that caused the damage could be livened without bridging to the tray.
Our rules are designed around dealing with single-fault situations that are "likely"; and as far as this sort of damage goes avoiding is preferable to dealing with the consequences. As Greg said; install for the conditions.