Regulation 543-2.4 and Type B Merlin Boards

[KiltedSparky]

Hi All,

Only my second post so please be easy on me lol

looking for a bit of clarification/help here, i have just checked a number of Merlin Gerin DBs which have the Main earth bolt installed direct to the metal enclosure and in some cases four earth bars in different places fixed to the same Metal enclosure via pot rivets and without any flying leads linking them to main earth is this a substantial means of earthing or can the pot rivets not be guaranteed by anyone/installer to withstand mechanical,chemical or electromechanical deterioration .

Thanks in advance for any help

 

[IQ Electrical]

A quick earth loop impedance test from line to each earth terminal block will give you an idea of the integrity.

It is good practice to link the earth terminal blocks.

 

[mogga]

IMO a flying lead from earth bar to Main earth even if its one fly lead (16mm) from bolt to bar to bar Unless the earth bar is Insulated from the body in which case it may be a clean earth

 

[malcolmsanford]

It's not unusual for Merin Gerin to have a large earth bolt with U type washers as their main Terminal espicially on TPN+E boards. What they normally do though is have a long earth bar coming off the bolt as a fixed attachment, I'm wondering if someone as removed the long single bar and fitted these 4 smaller to make indentifying which earth is associated to which circuit and Phase.

I know that some earthing points are riveted in, but normally you find that on the internal side of the rivet there is what I would could a nip washer which is fitted over the rivet before that are gunned. I personally don't like this, but as long as you can confirm continuity then really there is no problem.

 

[KiltedSparky]

A quick earth loop impedance test from line to each earth terminal block will give you an idea of the integrity.

It is good practice to link the earth terminal blocks.

Thanks IQ , it is a new install and the company have claimed the Pot Rivets are all that is required but i am in disagreement but also struggle to find a good argument apart from good practice

 

[malcolmsanford]

Yes, I would say she did the right thing. Instead of "hogging" you, she felt she did what she could and refer you to another professional. I do not know what the problems are, but I feel that if she lets you go like that and is being very frank and honest about it with you, then I guess she is being very professional. You don't have to take it personally at all.

I see that someone opened the doors again.

 

[KiltedSparky]

I see that someone opened the doors again.

Thanks Malcolmsanford, all these DBs appear to be designed the same way and all the earth bars have a connection big enough for a 16mm flying lead but agree good practice does not always mean that it has to be installed that way so will have to accept that if continuety is good then so be it .

Not sure how to reply too Mnerobi 15 though lol

Thanks again

 

[KiltedSparky]

IMO a flying lead from earth bar to Main earth even if its one fly lead (16mm) from bolt to bar to bar Unless the earth bar is Insulated from the body in which case it may be a clean earth

cheers Mogga , i agree totally but dont have regulations to back it up