High leakage equipment?

[newfutile]

I have been asked to remove a 3 ph rcd from a vehicle entry gate, because they state it has an inverter power supply that can leak up to 160 ma .

this does not seem correct to me and i wonder of the implications of having no rcd if this leakage is to earth on touchable large metal gates.

any thoughts?

 

[Vortigern]

I would not do it. Let the people who are installing the inverter do it. If they are installing equipment that means compromising safety then they should take the risks associated with that.

 

[James]

why Is the rcd required?
and an extra word.

 

[newfutile]

why Is the rcd required?
and an extra word.

For additional protection i would imagine, the rcd is already existing , the company i work for has subbed the job to another company , who have asked us to remove the rcd due to likely tripping issues.
i wonder if a type B rcd would solve the problem?
the manual for the omron 3gmx2 mentions dual independent earths so its clearly a problem ,this supply also supplies 3 lifts and water pumps ,metal conduit to metal light switches on so on.

 

[timhoward]

If I have the right product, the manual also says:

Use an earth leakage breaker for circuit (wiring) protection between the power
supply and the main power supply terminals (R/L1, S/L2, T/L3).
An earth leakage breaker may malfunction at high frequencies as those generated
by an inverter. Use an earth leakage breaker with a large high-frequency
sensitive current rating.
When sensitivity of 30mA or even less earth leakage maybe required in certain
applications (e.g. domestic), short motor cable and convenient low-leakage
EMC filters should be selected. Check with your supplier for additional
indications.

It looks like not having one at all isn't an option.
As you said, selecting the right one seems to be the way forwards and I wouldn't be scared to phone them up and ask for advice.

 

[timhoward]

I've just also noticed this bit:

 

[pc1966]

For additional protection i would imagine, the rcd is already existing

Is "additional protection" actually needed?

If it is hard wired and using SWA or similar (i.e. no vulnerable buried cables near the surface) then I don't see any requirement for a RCD, other than high Zs in a TT case. More so if you have a CPC in the SWA as well, so dual earth paths (armour and copper CPC).

 

[newfutile]

I think additional protection is absolutely required , we know it may leak up to 160ma ,possible not all at 50hz it seems the manufacturers talk about special gfci which is an rcd by another name,it seems reckless to me to knowingly pass current down a cpc/earth

 

[pc1966]

I think additional protection is absolutely required , we know it may leak up to 160ma ,possible not all at 50hz it seems the manufacturers talk about special gfci which is an rcd by another name,it seems reckless to me to knowingly pass current down a cpc/earth

Almost all devices pass some current down the CPC, might be microamps, might be milliamps, might even be amps if you have a big enough installation. That is why RCDs come with all sort of trip thresholds depending on what they are protecting, with the fancy MCCB incomer types often being adjustable from 30mA to 5A or more, and delays from "none" to typically 1 second or more..

For sockets with high leakage current there is/was a recommendation in the regs for dual CPC so no single point of failure in the earthing arrangement to combat the risk of an open CPC under "normal" conditions, let alone having a L-E fault at the same time.

Here you could run a 2nd CPC in parallel with the feed cable if that risk is a concern. However, I would start by looking at how it is installed and if the existing arrangement looks reliable and is not in need of "additional protection" for and cable damage contact.

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