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Plug in Galvanic Isolator.. which one


Sofia

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Interestingly BT have recently announced they will no

longer be using Huawei in their core network.  The yanks are definitely not happy with huawei either.

 

on the GI front gibbo used to argue that a GI was a switch and therefore was illegal in the earth. He was wrong.

 

I have safeshore GI but made sure I got one with a status indicator and test it regularly (which is very simple).

 

the issue which wotever and others have explained clearly, is the potentially very high fault current that could flow very briefly in the event of a fault to earth which may destroy the diodes in the GI disconnecting your earth which is not good...

 

so as long as you understand that and have a GI with a status indicator which you test from time to time and always after an over current trip then the AYBC spec is irrelevant. Although may be an indication of some testing against a standard (AYBC) which is not recognised in Europe but could offer you some reassurance around the quality of the device. 

Edited by jonathanA
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50 minutes ago, jonathanA said:

gibbo used to argue that a GI was a switch and therefore was illegal in the earth. He was wrong.

I’ve never heard him say such a thing and it’s in direct contradiction to what he writes on the SmartGauge site. Care to offer some proof of this?

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It’ll be on this site somewhere... ?

 

you don’t  tend to forget your run ins with  gibbo although it would have been a long time ago 

 

I had a quick search and couldnt find the post so maybe my memory is wrong and it was some one else. 

Edited by jonathanA
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5 minutes ago, jonathanA said:

care to prove he didn’t 

How can anyone prove a negative? 

 

He would never have said they were illegal to sell, it is a ridiculous statement. Is 2006 early enough for you?

 

11 minutes ago, jonathanA said:

it would have been a long time ago 

 

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2 minutes ago, ditchcrawler said:

I think what he said there is correct

Absolutely. And nowhere has he ever said that they’re ‘illegal’. That’s just wrong. 

Edited by WotEver
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Are you accusing me of lying then ? 

 

I Think ive been fairly reasonable although frankly I don't see what it's got do with you. What I recall him saying was they contravene the regulations. I never said he said they were illegal to sell, you decided to put that spin on it for whatever reason.

 

suspect the GI / IT argument will run and run like the PO vs cassette debate 

 

 

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8 minutes ago, jonathanA said:

I never said he said they were illegal to sell

 

2 hours ago, jonathanA said:

gibbo used to argue that a GI was a switch and therefore was illegal 

QED

44 minutes ago, ditchcrawler said:

I think what he said there is correct

I’ve just spent the last hour re-reading that thread. It’s still valid today. 

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Just now, Traveller said:

is there any downside protection-wise with the plug-in variety

Nope. The protection of a GI is offered by a few diodes and (usually) a capacitor. Whether that’s inline or inside the boat doesn’t affect its performance. 

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19 minutes ago, Traveller said:

Apart from the convenience of heaving a fixed GI is there any downside protection-wise with the plug-in variety. Plug-ins will not be earthed to the hull so I wonder if this has any impact on performance?

The earthling is still the same

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15 minutes ago, Traveller said:

On the basis that there is an earth from the consumer unit to the hull?

I’m not understanding this question. Adding or not adding a GI has no effect on bonding the hull. 

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4 minutes ago, Traveller said:

I always understood that a GI when installed inboard was earthed to the hull (mine is). As an in-line version will not be earthed to the hull I wondered if that would impact performance in any way.

The incoming earth must be bonded to the hull. Whether that incoming earth comes via a GI, IT, or direct has no effect on that bonding. 

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Where the physical bond is made (behind the shoreline socket, from the Consumer Unit, elsewhere) makes no electrical difference. If the bond is made from the CU (like in a house) then this is nice and logical for anyone working on the system, so I would always advocate that’s where it should be done even if it makes no difference electrically. 

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On 16/01/2019 at 23:00, TheBiscuits said:

 

 

You are doing what @Flyboy was doing earlier in the thread.

 

The 30A or 60A is the continuous current the GI can carry in normal usage.

 

The 5000A current is the current it can withstand long enough for the trip to blow in a catastrophic fault condition.

 

 

It wasn't me doing it. I knew intuitively that the 500 amp rating specified on some GIs couldn't be the same thing as the Safeshore 70 amp rating. The 70amp rating is continuous whereas the 500, 750, or 5000 amp ratings are max surge capacity so it's a bit misleading. Some people weren't comparing the same thing. The Safeshore 70 amp GI has a peak current rating of 500amps.

Edited by blackrose
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22 hours ago, Traveller said:

Apart from the convenience of heaving a fixed GI is there any downside protection-wise with the plug-in variety. Plug-ins will not be earthed to the hull so I wonder if this has any impact on performance?

Despite what others have said I think there may be but not on the protection side of things because you introduce two more points of potential failure in the supply, namely the two extra pos & neg connections in the two plugs. We have a very recent thread where this seems to have happened. I also wonder about the effect of the two extra earth connections corroding badly but anm not sure how this would affect the protection.

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On 16/01/2019 at 23:03, WotEver said:

Agreed, but a good 1960’s car wouldn’t be considered as a good car today. In the same way more is understood about failure modes of GIs and what used to be considered a good spec a few years ago wouldn’t be considered a good spec today. The IEE regs have now progressed to the 18th edition not for fun but because more is understood, better products are available, better working practices are mandated etc. Likewise a GI that can fail and give you no earth protection at all is obviously not a good idea, hence the AYBC guidelines. 

No. You either have a GI that fails ‘safe’ in accordance with the AYBC spec, or better, use an IT that doesn’t concern itself with such matters. 

No they don’t. It’s 5000A for the FS GIs. 

As you say, AYBC are guidelines not regs. I'm not quite sure why we're using American recommendations in this country anyway? Why don't we have our own?

 

You're still saying 5000A for the Sterling GIs but you said 70A for the Safeshore when in fact it's 500A FS. I accept it still doesn't compare so I'll probably upgrade, but you definitely were comparing two different things. 

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14 minutes ago, blackrose said:

 

 

It wasn't me doing it. I knew intuitively that the 500 amp rating specified on some GIs couldn't be the same thing as the Safeshore 70 amp rating. The 70amp rating is continuous whereas the 500, 750, or 5000 amp ratings are max surge capacity so it's a bit misleading. Some people weren't comparing the same thing. The Safeshore 70 amp GI has a peak current rating of 500amps.

Can you give a link to that please?  The sales literature linked above states 63A max continuous and 70A fault mode, and uses the 10% safety factor as a selling point.  I couldn't find anything suggesting it can handle 500A or 5000A fault current in their specifications. 

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2 minutes ago, TheBiscuits said:

Can you give a link to that please?  The sales literature linked above states 63A max continuous and 70A fault mode, and uses the 10% safety factor as a selling point.  I couldn't find anything suggesting it can handle 500A or 5000A fault current in their specifications. 

I've just spoken to them. 70amp is continuous and 500A peak. I don't have a link sorry. I never said 5000A?

Edited by blackrose
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