Form of Separation in Panels 1

[NickParker]

What is the criteria for deciding the form (Form-1, Form-2, Form-3, Form-4) of separation of panels (MCCs, LV Switchgears, LV Switchboards)?

Does it have any relation with total power consumption of the panel, draw in-out construction etc?

I always mention as Form-1 when there is no such specification written in the contract and will only change it when the owner/consultant ask us to change it

I understand that form of separation is associated with the IEC standard, but I also wonder how is it followed in NEC land too

 

[ScottyUK]

Generally down to customer preference over in the metric world, but Form 4 Type 7 designs are certainly prevalent at the heavy end of the market. I'd be pretty vocal in opposing an MCC or switchboard with a lesser degree of segregation due to operational difficulties it would present in an increasingly risk-averse society where work in or around energised conductors is already hard to justify - and rightly so.

At the smaller scale where you're maybe considering an MCCB panelboard or similar then a lesser degree of segregation is expected, but an occasional board outage is more easily tolerated when necessary.

 

[che12345]

Dear Mr NickParker,

Q1. What is the criteria for deciding the form (Form-1, Form-2, Form-3, Form-4) of separation of panels (MCCs, LV Switchgears, LV Switchboards)?
A1. The main criteria are a)dependent on the competency of the maintenance staff b) how important is the board C) can the board be [switched off] for fault finding d) current rating etc...
A1.1 The higher the form of separation the higher the cost and physical size. Larger breakers, components and busbar size etc., due to higher temperature-rise.
A1.2 The local regulations/standards compliance. My understanding is, IEC treats the Form of separation as an [optional item to be agreed upon between the user and the builder]. It is [not] a Standard. Therefore, it is [not] a mandatory requirement.

Q2. Does it have any relation with total power consumption of the panel, draw in-out construction etc?
A2. It is [independent] of the power consumption/current rating, fixed or drawout construction/design.

Q3. I always mention as Form-1 when there is no such specification written in the contract and will only change it when the owner/consultant ask us to change it.
A3. For commercial/price reasons, Form 1 is usually offered {unless written in the contract and agreed upon] (see above A1.2).

Q4. I understand that form of separation is associated with the IEC standard, but I also wonder how is it followed in NEC land too
A4. The term "Form of separation" appears in IEC Standards publication (IEC 61439-...). It is neither mentioned nor practiced in the NEC land.
A4.1 FYI IEC Standards covers very comprehensively in "degree of protection" (e.g. IPnn-xy) etc. A different classification system is being used in the NEC land.
Che Kuan Yau (Singapore)

 

[FreddyNurk]

I agree with ScottyUK, higher forms of separation for equipment for me are effectively mandatory unless there are mitigating circumstances. The 61439 series appears to be more comprehensive than what 60439 was in terms of type testing / design verification, at least from what I've seen from the manufacturers, but then again I'm used to seeing Partially Type Tested Assembly where the only thing that had actually been tested was the busbar.

How that applies to NEC I can't comment on.

EDMS Australia