AMD 3 and "non-combustible" CUs...
- Thread starter ban-all-sheds
- Start date
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It does look faulty.
It'll need more than a bit of WD40...
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Yes, but it is a DB …….
DS
It is, but ...Yes, but it is a DB …….
In 421.1.201 Mr BS7671 said:
Kind Regards, John
I liked this bit "The affected connection in the distribution board was found to be considerably tighter than others on the same component which caused a deformation of the wiring and over time caused the connection to loosen and generate considerable heat, according to the report."
Interesting! Does this mean that we should leave all connections loose, so that they can tighten up over time and thus be safer?I liked this bit "The affected connection in the distribution board was found to be considerably tighter than others on the same component which caused a deformation of the wiring and over time caused the connection to loosen and generate considerable heat, according to the report."
Kind Regards, John
I also noticed that a member of the museum staff opened what they referred to as a "fuse board", so when open it wouldn't have been enclosed!
Full report here:
http://www.surreycc.gov.uk/__data/a...2/Fire-investigation-report-Clandon-Park-.pdf
Has photos of the DB pre fire, also the the problem neutral connection - looks to me like it might have been tightened to the point that the brass connection bar fractured on one side resulting in a loose connection.
http://www.surreycc.gov.uk/__data/a...2/Fire-investigation-report-Clandon-Park-.pdf
Has photos of the DB pre fire, also the the problem neutral connection - looks to me like it might have been tightened to the point that the brass connection bar fractured on one side resulting in a loose connection.
It looks as though the db had no front cover :s
Interesting, I'm surprised that short factory connection was a 7 strand wire. I would have expected a solid formed bit of copper, or a fine stranded length of wire.
It might mean that there are recommended torque values for good reasons.
Maybe simple semantics but for a guy with all those training tickets he should have referred the neutral bars as serving circuits rather than "fuses"
As per freddo's comment the main neutral connection onto bars is always a physical weak point that manufacturers need to address by beefing up that particular connection point
As per freddo's comment the main neutral connection onto bars is always a physical weak point that manufacturers need to address by beefing up that particular connection point
If it had been smouldering inside the metal case then opening the case would have allowed more air to reach the smouldering items and then they would have ignited into flame and spread.
The report says """He went to the fuse board to investigate the loss of power and on opening the cupboard discovered that there is a fire inside. """
Cupboard or distribution box door ? ( was there a door on this type of distribution board ).
If there was no door on the distribution board then other material in the cupboard could have been ignited by burning debris dropping from the distribution board. That might not have happened if the distribution board was fully enclosed. ( as required for domestic consumer units by ammendment 3 ).
That said a prolonged intense electric arc inside a closed steel box can raise the external surface temperature high enough to ignite any paint on the surface and maybe hot enough to ignite material close the the box. A loose Live wire fused at 100 amps bouncing around inside an earthed metal box will create a lot of arcs and heat. The same Live wire loose in a plastic box is not going to arc unless it touches metal that is either Earth or Neutral.
The report says """He went to the fuse board to investigate the loss of power and on opening the cupboard discovered that there is a fire inside. """
Cupboard or distribution box door ? ( was there a door on this type of distribution board ).
If there was no door on the distribution board then other material in the cupboard could have been ignited by burning debris dropping from the distribution board. That might not have happened if the distribution board was fully enclosed. ( as required for domestic consumer units by ammendment 3 ).
That said a prolonged intense electric arc inside a closed steel box can raise the external surface temperature high enough to ignite any paint on the surface and maybe hot enough to ignite material close the the box. A loose Live wire fused at 100 amps bouncing around inside an earthed metal box will create a lot of arcs and heat. The same Live wire loose in a plastic box is not going to arc unless it touches metal that is either Earth or Neutral.
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