Electrical Enclosures

[keithc]

I have just had a quote through from a prospective supplier for some LV (415v) distribution panels. He has quoted for the panels to be type 'form 4', which I believe is something to do with the internal make up of the panel to allow for access whilst other parts of the panel are live. Does anyone have an idea where I can find more info about this, as I do not think I need it to be that critical, i.e. if I'm working on it , I'll turn the whole thing off.
Cheers,
Keithc

 

[jbartos]

Suggestion: Please, could you reveal more info about those panels, e.g.
NEMA enclosure type (there are NEMA enclosures 4 and 4X)
Manufacturer data
Catalog numbers
Etc.

 

[guthrie]

IEC439-1: Type tested and Partially Type tested Assemblies specifies the following;
Form 1 No Separation.

Form 2 Separation of busbars from the functional units.

Form 3a Separation of busbars from the functional units and separation of all functional units but not of their terminals for external conductors, from one another. The terminals for external conductors need not be separated from the busbars.

Form 3b Separation of busbars from the functional units and separation all functional units from one another. Separation of the terminals for external conductors from the functional units, but not from each other.

Form 4 Separation of busbars from the functional units and separation all functional units from one another, including the terminals for external conductors which are an integral part of the functional units.

Typical examples of the arrangement can be found in the IEC439-1.