Means of isolation

[scratchy]

Hi Folks, Maybe a schoolboy issue, but, the scenario. I have a 3 phase cct for a car ramp. It's fed by a 4mm swa which comes off an MEM board via 3 pole MCB to a 32A TP&N MEM Fused (HRC) isolator. My question is: Does it need to be locally fused or can it just be a switch?

 

[Plonker 3]

No is the simple answer as long as manufacturers instructions are followed.

 

[uksparks]

As Dillb says more than likely no.

If the manufacturer data states that it needs to be fused locally then do so, but your circuit is protected appropriately anyway.

 

[Engineer54]

The commercial ramp still needs a means of Local Isolation though, just not necessarily a ''Switch Fuse''!!

 

[uksparks]

Sorry i was lost in the fusing of it, yes, it would need a local point of isolation, presumably is has one built into of part of the ramp does it not?

 

[Pete999]

Any item of equipment like the one you are describing needs a lockable isolator for maintenance purposes surely.

 

[GMES]

Sorry i was lost in the fusing of it, yes, it would need a local point of isolation, presumably is has one built into of part of the ramp does it not?

I get what your saying but, I would still want to see a local isolator to allow complete isolation so there is no voltage coming into the Ramp control panel. 100% safe then.

 

[Rockingit]

Surprised it doesn't need an E-stop as well, as it's a large moving part? Not that that's necessarily isolation in this sense, I know.

 

[topquark]

Agreed, any form of energy (elec/hydrolics etc) warrants a risk assessment and treating accordingly from an HSE perspective.

 

[GMES]

Agreed, any form of energy (elec/hydrolics etc) warrants a risk assessment and treating accordingly from an HSE perspective.

Hydraulics........Sorry :wink5:

 

[Knobhead]

Surprised it doesn't need an E-stop as well, as it's a large moving part? Not that that's necessarily isolation in this sense, I know.

If you introduce e-stops in to a propriety control system then you’d better be sure what you are doing. You could end up on a sticky wicket if anything goes wrong.

 

[Darkwood]

32amp fused up and downstream is not needed as this will give discrimination issues, If the car ramp has a lockable isolation and requires a tool to access thenyou don't even require an isolator, this applies if its an interlock where access to the electrics cannot be gained without the power been disconnected (except to the interlock supply side which will be marked and finger safe. If the isolator switch does not interlock with the access panel and you can gain access without switching off then all electrics internally will be required to a higher safety standards ....gaurds over terminals, finger safe, warnings etc.... this is usually done where access may be required by the operator to adjust or reset an item.
Regarding the above this applies if a tool is required to access the electrics ..when I say tool I don't mean another word for the operator either I mean a screwdriver or keylock etc.

All this been said its always best to have a separate isolator on the wall etc as this allows other service companies to completely isolate the ramp as some companies now won't service equipment where this is not the set-up.

 

[scratchy]

Thanks all. I just couldn't find anything to say either way. I will without doubt make sure there is local isolation as I would have. I just thought it a OTT to stick HRC on a cct protected by MCB.
Cheers again
Steve