Dr Glover provides expert electrical evidence on the fridge-freezer fire initiation, discussing wire crimp analysis, overheating mechanisms, and protective measures in domestic appliances.
00:00:07 you
00:07:22 you
00:13:47 isn't
00:14:09 do sit down Gila yes we're just gonna thanks dr. Glover thanks so much for coming back we were discussing why MJS
00:14:21 coming back we were discussing why MJS won before the break can we return to that in particular referred to a photo met quadruple zero nine zero seven seven
00:14:37 now can you just confirm for us of what this photograph shows this is the remains of the compressor from the fridge freezer in flat 16 and in on the
00:14:50 fridge freezer in flat 16 and in on the front view this would actually be the left side of the compressor review of behind the fridge looking at it but you're looking at the compressor relay compartment the remains of it and components within it and as we're
00:15:03 components within it and as we're looking on it is the looking at it rather is the wire on the left 6e oh yeah I think I cannot answer that again I didn't I was not present during
00:15:14 again I didn't I was not present during when when when the compressor components were still affixed to the compressor I only saw them in separate bags so I
00:15:28 only saw them in separate bags so I cannot tell you which is six B or six C I don't have a scale to measure things there so I could try to do an analysis in the future but I can't identify which
00:15:39 in the future but I can't identify which which is 6 B which is 6 C okay now if the one on the left is 6 e for the purposes of a hypothesis would the arc
00:15:51 purposes of a hypothesis would the arc damage part of MJS worn need to be located at the end of 6 C it's a hypothetical question given you a
00:16:02 hypothetical question given you a previous antigen
00:16:07 well 6c is approximately 7 centimeters in length and could you repeat that
00:16:18 in length and could you repeat that question yes of course it's on the hypothesis that the wire on the left is 6c okay would the arc damage part of MJS
00:16:29 6c okay would the arc damage part of MJS warm be located after the end of 6c yes it would but can I ask you to turn back to your addendum and figure 7 which is
00:16:41 to your addendum and figure 7 which is at page 13 now if the the path of the
00:16:53 at page 13 now if the the path of the short-circuit is illustrated with the red zigzag and the bottom right hand corner I think is that right yes sir and otherwise that participate in the short circuit that you say was caused by the
00:17:04 circuit that you say was caused by the overheated crimp located inside the compressor relay or not yes yeah they were located inside the compressor relay compartment
00:17:15 compartment yes I'm looking at figure 7 itself where would you place MJS one considering the
00:17:28 would you place MJS one considering the number of wire strands in MJS 124 strands per wire okay which is consistent with the line capacitor wires okay you have the run capacitor okay
00:17:41 okay you have the run capacitor okay here's one capacitor run capacitor wire here another one here now these look like short sections do you remember that the run capacitor is not within the relay compartment this over here no okay
00:17:54 relay compartment this over here no okay so you pull this run capacitor out and bring these two wires his one here's two both of which in his and a continuation of it bring these two wires out and then
00:18:06 of it bring these two wires out and then bring them into the compressive compartment and then hook them up to these two locations nicely said can you help um to an extent apology this may be me but you've got
00:18:17 apology this may be me but you've got the part of the short circuit shown by means of the zigzag on the left-hand side yes if you place MJS worn in or near the wrong capacitor which is how it
00:18:29 near the wrong capacitor which is how it what I understood you were saying yes why is the puff the short circuit not near the wrong class again this is just a circuit diagram okay these two wires the run capacitor wires extend out so
00:18:42 the run capacitor wires extend out so even though I'm showing the short circuit here if I if I could run this over here I'm just trying to illustrate here a short circuit that bypasses the
00:18:54 here a short circuit that bypasses the clicks on overload relay and the compressor itself now again these two wires for the run capacitor are running out of the relay compartment so if you
00:19:08 out of the relay compartment so if you wanted to I could bring this over here okay and you get the same effect understand could I now deal with the far initiation scenario itself and looking
00:19:21 initiation scenario itself and looking at the mechanism of overheating what testing have you done to ascertain the electric current that flows through 6b Bravo
00:19:31 Bravo when fridge/freezer is running normally that would be below the compressor load now we'll start with thee with the power
00:19:45 now we'll start with thee with the power supply cord for the fridge freezer has 813 ampere fuse on it so we're talking about a normal load current for the entire fridge freezer of let's say 10
00:19:58 entire fridge freezer of let's say 10 amperes just to give you a rough number approximately now when the compressor is on okay
00:20:06 on okay I would estimate that and it's my estimate of in the range of 5 to 10 amperes for the compressor load current under normal conditions when it starts up it's it's much higher a compressor
00:20:19 up it's it's much higher a compressor motor when it starts could be 5 or 6 times that but after it gets into the normal running current I would estimate the the compressor load current in the inner age
00:20:30 compressor load current in the inner age of 5 to 10 amperes were you able to measure the post-fire electrical resistance of the connection within six bb4 Bravo no I did not do that would
00:20:43 bb4 Bravo no I did not do that would that be possible well you could certainly pull out a
00:20:51 device and electronic leader to try and measure resistance but how meaningful that would be I would question you have a connector that has gone through a fire
00:21:04 a connector that has gone through a fire it's heavily fire damaged and then after the fire it was exposed to moisture and the possibility of additional corrosion rust so in my opinion that would be it
00:21:18 rust so in my opinion that would be it certainly could be tried but I wouldn't find that too meaningful
00:21:24 thank you turning now to the wire crimp just understanding that it's basic design does it include internal serrations on the barrel of the crib yes
00:21:39 serrations on the barrel of the crib yes yeah I wouldn't call them serrations I call them ribs perhaps and these are used to clamp the wire strands together in the electrical connector just to understand excuse me the basic crimp
00:21:51 understand excuse me the basic crimp design has serrations is that right yes yeah and the purpose of those serrations is to clamp the wire strands together in the connector yes and clamp them to the
00:22:03 the connector yes and clamp them to the barrel the wire barrel itself and looking at 6a and 6b are they two different crimp designs do you think we should see them yes I'm just trying to come he said that now try to remember
00:22:14 come he said that now try to remember what what the reference would be there I'm a puppy that you don't need it just to deal with 6a and 6b the only difference be as I mentioned has 14 plus
00:22:28 difference be as I mentioned has 14 plus 23 that's 37 wire strands in it 6a has 20
00:22:34 20 Austrians so whether they're the identical connectors I can answer that they look very similar in design but they may have different model numbers in
00:22:46 they may have different model numbers in order to accommodate different sized wire strands but they are similar in design oh if we go back in your addendum
00:22:58 at page six does this provide any help it may not actually to illustrate the
00:23:10 it may not actually to illustrate the point you've made again they look very similar however I would have to do a dimensional analysis perhaps even look I
00:23:22 dimensional analysis perhaps even look I don't know if you could find some model numbers on the remains of these crimps they're very very similar but I can't say they're identical of the identical model now staying with this page and
00:23:36 model now staying with this page and looking in particular the figure to the top suite of pictures is it fair to say
00:23:47 top suite of pictures is it fair to say there are multiple points where the Y's and 6b are tightly clamped just looking at what we see in these cross-sectional
00:23:58 at what we see in these cross-sectional slices there okay so we're looking within the wire barrel itself yes and now we have to look at cross-sections
00:24:11 now we have to look at cross-sections yeah so and that's where we're looking about the clamping my opinion looking at the shape of the connector not projecting not the curved portion of the barrel projecting inwards also looking
00:24:25 barrel projecting inwards also looking at this space which is wide over here and then narrows down I believe that the space you referred to there again is spatially referring to earlier on the space between the two wire barrels illustration at the top of yes yes so I
00:24:37 illustration at the top of yes yes so I don't consider this a tie connection so now what was your question exactly well the question is really are there multiple points illustrated by
00:24:48 there multiple points illustrated by these cross-sectional slides where the wires are tightly clamped is that a proposition you'd accept or not I would not use the word tightly clamped there our location where wire strands are in
00:24:59 our location where wire strands are in contact with each other and there are other locations where there are void spaces I would not consider this a tight clamp I would not consider any of these a tight clamp because of the the lack of
00:25:16 a tight clamp because of the the lack of the curvature portion of this barrel projecting more into the strands which you can compare with the lower figure for 3a and looking going back to the top
00:25:28 for 3a and looking going back to the top of figure 2 looking at the wild wire barrel itself there appear to be looking at the top wire two or possibly three ribs is that correct reading of that
00:25:39 ribs is that correct reading of that there are red sections yes now are you able to say whether there's a correlation between the location of the ribs and the location of the voids illustrated in the cross-sectional slices below there are 88 0 slices here
00:26:00 slices below there are 88 0 slices here that the CT scan gave us and there are voids in every slice there would you're going to have some slices in between ribs some slices under ribs both of
00:26:12 ribs some slices under ribs both of which have voids so I'd say there's no correlation there however I would say that the slices that have large voids such as this Center 1 are likely
00:26:25 such as this Center 1 are likely correlated with the ribs and to some extent can we draw any reassurance from the fact if we're looking at the center cross-sectional slice yes there's a green line an arrow immediately above it if we follow the line up does that reach
00:26:38 if we follow the line up does that reach a rib in the lowest wire wire barrel I does now
00:26:44 does now I have to be careful here I selected a
00:26:50 cross-section more or less in the middle of the wire barrel and that I drew a line from what I considered to be the middle of the wire barrel down to this I
00:27:01 middle of the wire barrel down to this I can't say that that is aligned with a rib so it even though I'm showing it like that
00:27:07 like that I didn't honest I did not specifically say yes this came from that rim this cross-section came from more or less the center of the barrel this cross-section
00:27:18 center of the barrel this cross-section came from the left end this cross-section came from the right end so when I drew this I was not thinking of ribs I was just picking five cross
00:27:29 ribs I was just picking five cross sections that were broadly scan the entire length of the barrel understood now can I turn to the
00:27:44 understood now can I turn to the hypothesis on on the spread on the fire spread the initial fire spread insofar as it concerned MJS warned now is it a is it a correct assumption that the
00:27:55 is it a correct assumption that the snorer you've set out in the addendum report is based upon the fire starting within the real a compartment of the fridge/freezer yes yes now if MJS one
00:28:07 fridge/freezer yes yes now if MJS one was located outside the relay compressor how did overheating in jdg six be caused arcing on MJS one did you say the
00:28:18 arcing on MJS one did you say the diffused section of mgesa one is located outside the relay compartment no simply if MJS one was located I put it more generally than Mercer the important part is the fused section
00:28:32 the important part is the fused section of MJS one I'm sure that again I have concluded that MJS one was associated with this fridge/freezer and ran into the relay compartment but certain part
00:28:46 the relay compartment but certain part of that ten centimeters must have projected outside of the relay compartment heading towards the run capacitor
00:28:54 capacitor and can you help us with it how the the fire would have traveled from within - without the compartment before the
00:29:07 without the compartment before the short-circuit or after the troll festival so you're placing just want to get your premise you're assuming that the fused section is outside of the relay compartment if we assume it's
00:29:18 relay compartment if we assume it's within well then your your you don't need the fire doesn't need to travel outside but a fuse section is within the relay compartment and that's my opinion as my conclusion and the the line to
00:29:30 as my conclusion and the the line to neutral short-circuit that gives you the arc damage to MJS one is all within the relay compartment now in relation to the
00:29:43 relay compartment now in relation to the scenario you've postulated in the addendum report are you able to identify which two wires touch each other in the short circuit that you've set out and illustrated in Figure 7 yeah well one of
00:29:55 illustrated in Figure 7 yeah well one of them had to be an energized wire that would be jdg 6b or an extension remember we've only got about seven centimeters of it and then it ends so you could
00:30:06 of it and then it ends so you could think of the end of that six B Bravo bridging across the run capacitor wires in causing a line to neutral short-circuit no this may follow from a
00:30:18 short-circuit no this may follow from a question I asked before lunch but are you able to assist us with what you think came first was it the short circuit or the overheating connector the overheating connector in my opinion was
00:30:30 overheating connector in my opinion was the first event that started burning the insulation on the wires that led to a short circuit now if that's so with the full path of the current through that
00:30:41 full path of the current through that connector during normal operations would it operate at about maximum of 0.4 amps or there abouts point 4 amperes yes I
00:30:52 or there abouts point 4 amperes yes I don't know where you got that number I maybe I don't understand the question repeat that yes of course what I'm if you say which you do that the overheating connector came first do you
00:31:05 overheating connector came first do you accept the full path of the current through that connector during normal operations would be a maximum of 0.4 amps no could you give the reason why you don't excel at well you just we need
00:31:17 you don't excel at well you just we need to know what the compressor load is and I have not calculated that but I I'm assuming that it's more than that okay
00:31:31 now would you agree with the proposition that there were additional wires in the exemplar compressor relay compartment that you reviewed compared to the flat 16 fridge/freezer
00:31:42 16 fridge/freezer and by way of example do you agree that there was a jumper relay system the exemplar but not in the flat 16 fridge/freezer okay I think I understand your question
00:31:53 okay I think I understand your question but if you could repeat that one more time yes of course do you agree with the proposition that there were additional wires in the exemplar compressor relay compartment compared to the flat 16 fridge/freezer
00:32:04 compared to the flat 16 fridge/freezer and by way of example there was a jumper relay system in the exemplar but not in the flat sixteen fridge/freezer yes that's a possibility the exemplar exact
00:32:18 that's a possibility the exemplar exact design and manufacture may have some differences including as I as you say I observed some small jumper wires it's in one of my figures in the report within
00:32:30 one of my figures in the report within the relay compartment of the exemplar fridge/freezer which may not be associated they may not have those jumper wires within the subject
00:32:43 jumper wires within the subject fridge/freezer with that difference have any material impact on the reasoning you set out in your addendum on the hypothetical and can you help us why not
00:32:56 hypothetical and can you help us why not because I am associating the short circuit with 6 B which has no that has 23 strands and 14 strands in it and that
00:33:08 23 strands and 14 strands in it and that would have been energised when the compressor is on and and that's where the overheating crimp is and that is what would have arced to the run capacitor wires thank you and
00:33:20 the run capacitor wires thank you and are you able to say whether the length of the wires in the flat 16 fridge/freezer were longer or shorter than the wiring and the exemplar
00:33:36 we have to take the wires one at a time let's talk about the run capacitor wires the run capacitor is not within the relay compartment it's if you're behind
00:33:47 relay compartment it's if you're behind the refrigerator it's over to the left and so and the run capacitor as I understand it would be a separate component not necessarily supplied by
00:33:58 component not necessarily supplied by the compressor manufacturer that would be what the company that manufactured the fridge/freezer would be connecting with in the relay compartment I would
00:34:09 with in the relay compartment I would assume that the run capacitor wires would be similar for an exemplar or whether it be an embryo or to come so if they were shorter for example in the
00:34:21 they were shorter for example in the flat 16 fridge/freezer would that have any material impact on the reasoning you set out in the addendum no but again they can't be sure do they have to I know where the run capacitor is on the left end of the
00:34:34 capacitor is on the left end of the mounting plate for the compressor it's off to the left if you're behind and then these work wires run to the from the run capacitor to the relay compartment they have to be
00:34:46 to the relay compartment they have to be a similar length whether it be to come sir or an in record dr. klevor thank you I now come on to the my final topic which I'll deal with briefly now given
00:35:00 which I'll deal with briefly now given your experience of electrical fires in the United States can you help us with what protective measures are fixed the back of domestic fridges so as to contain fire yes this is an area that I
00:35:14 contain fire yes this is an area that I did not address in my important but the one difference that I've seen is in the United States the back casing the rear casing of refrigerators are required by
00:35:27 casing of refrigerators are required by underwriters laboratory standards to be manufactured of metallic steel let's say steel not plastic whereas here in the UK
00:35:38 steel not plastic whereas here in the UK and I think in Europe also that you are allowed to manufacture refrigerators with a back casing that is plastic are you able on the basis of
00:35:50 is plastic are you able on the basis of your experience give us any assistance how effective the the metal casing is in America to containing fires that's thought within a fridge just in a
00:36:01 thought within a fridge just in a general view again you're starting to get outside of my area of expertise I'm an electrical guy but you can imagine a fire starting within a refrigerator and with a steel backing now that backing
00:36:15 with a steel backing now that backing does not span the entire length of refrigerator there is an open space down below with where the compressor is located but that steel backing would help to contain an internal fire keep it
00:36:31 help to contain an internal fire keep it within the refrigerator for a longer time and also prevent and you have less combustible now instead of a plastic casing on the rear which is combustible contributing to the fire you know how
00:36:42 contributing to the fire you know how have a steel casing that is not but that's just so in a layman's terms again because I'm not a cause and origin person doctor cover I'm very grateful
00:36:53 person doctor cover I'm very grateful for your assistance sir may I ask for the usual five minutes or so to see if there are any points which I oughta have covered yes well we usually have a little break at this point Council thinks he's run out of ammunition but he
00:37:05 thinks he's run out of ammunition but he needs to just check that that's the case so we'll have just over five minute break and talk to an encore special evidence when you arrive to the room and
00:37:16 evidence when you arrive to the room and if you'd like to go in the action we'll come back at 25 to 3 thank you sir thank you very much
00:37:32 right 25 to 3 minutes thanks it
00:43:43 you
00:47:23 and asked mr. Kinnear whether he's got any more questions but I'd be surprised if he didn't have one or two should we just see so there are two unique events which have happened today one we finished before 5:00 and second
00:47:36 one we finished before 5:00 and second unique event is that there are no supplemental questions so leaves me simply say dr. Glover thank you very much for attending today to give evidence it's been very helpful indeed dr. Glover can I think you please on
00:47:48 dr. Glover can I think you please on behalf of the inquiry as oh I found your evidence really interesting and very useful and if I may say so very clearly put and thank you for giving us the benefit of your expertise very very
00:48:01 benefit of your expertise very very grateful to you my pleasure thank you very much indeed so that's it so if you'd like to go in the air she'll look after you and we can
00:48:13 the air she'll look after you and we can bring those out a few later on thank you very much
00:48:28 so there are two final points before we rise state and the first one of which is to thank mr. penfold who has been the documents director of a significant chunk of inquiry this is his last day
00:48:40 chunk of inquiry this is his last day assisting today so if I may on behalf of the entire CTI team plus on our thanks to him his patience has been exemplary I think well I think we all owe him a great debt of gratitude thank you very
00:48:51 great debt of gratitude thank you very much indeed and so the final matter is that concludes the evidence today right now that we have professor Nick Dade at 10 o'clock tomorrow oh good thank you very much well sir we all get
00:49:02 thank you very much well sir we all get an early afternoon but I'm sure you can make good use of it we'll break now and resume at 10 o'clock tomorrow with our next witness thank you very much