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Retrofitting SPDs - Industrial Environment

Elliot0114

Hi, apologies if this has been discussed previously but I’m after advice on retrofitting SPDs onto an existing installation which doesn’t currently contain any in an industrial environment. The installation is a 400V DNO supply to a main MCCB switch in one building which then supplies a large 400V Panel in a separate building, which contains multiple existing supplies and a spare switch which I am planning to use to supply my new equipment.

 

The DNO and MCCB switch don’t have anywhere practical to connect the SPD device which would mean amending the supply arrangement so the SPD can be added in.

 

Is it as simple as If I am not amending the existing supply arrangement, I just need to add a Type 2 SPD to protect my new supply and a potentially a Type 1 SPD onto the Panel for additional protection if it is easy to do so?

 

In the regs it says the SPD should be installed ‘as close as possible to the origin of the electrical installation’ but the SPD manufacturer stated it should be as close as ‘practicable’. Is the practicable statement correct or is that just a common sense approach?

 

Thanks in advance for any advice. 

  • 0

    This might be one to check with the manufacturer.

    I have been advised that if the distance from the first SPD is > 20 m, another may be required because whatever slips past the first one can resonate. So you put another one at the next DB.

    It seems to me that if there is nothing to protect until final circuits are reached, one SPD at each final DB should suffice.

    As with the OP's installation, it is not possible for me to add an SPD at the origin without installing a larger DB and that would be too much effort.

    Type 1 SPDs go with lightning protection systems.

  • 0

    ‘as close as possible to the origin of the electrical installation’

    To my mind there's a correlation between SPDs and bonding - after all it's no good shorting live conductors to c.p.c.s if the extraneous-conductive-parts some of your equipment is in contact with are at some completely unrelated potential. Given that where a single installation spans several buildings,  we repeat main bonding at the intake of each building, it makes sense to me to repeat the "origin" SPDs at that position too. The flipside of that argument coin is that if you've already put origin style SPDs in your local building (to cover all your new work), is there any immediate need to do the same at the official "origin" of the installation in a different building?  I'd suggest (from the point of view of physics rather than the lettter of the regs) probably not.

       - Andy.

  • 0
    Elliot0114 said:
    Is it as simple as If I am not amending the existing supply arrangement, I just need to add a Type 2 SPD to protect my new supply and a potentially a Type 1 SPD onto the Panel for additional protection if it is easy to do so?

    Not always.

    It may require the installation to be assessed as a whole.

    Don't forget also, switching transients as well as indirect lightning transients in this type of environment.

    Most importantly, though, does the building have an LPS (or is it adjacent to another building with an LPS)? If so, this would have to be assessed under BS EN 62305 series and not BS 7671.

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