# Useful websites for electrical work



## Pudsey_Bear (Sep 25, 2008)

I've been doing a bit of electrical work on the MH for a while now, and have had some good advice of some of the members, but sometimes you get conflicting advice, so I then need to find confirmation of what I've been told.

My biggest problem is a lot of the time I just don't know enough, so need to read up on it.

Here are a few websites which might help others to help them selves, meanwhile I'll struggle on.

This one has some downloadable software (not free)

 this one does it online, Wire calculator

Wire Gauge and Current Limits

Wire size calculator

Another wire gauge calculator

and another

not sure if this is useful

always wondered what those sizes meant, here's the answer

more useful for MH calculations

Low Voltage Lighting Cable Selector

I hope some of you find at least some of the above web sites of use, maybe not now but for a later project.

It is my way of putting a little back into the site which has helped me so much since I joined, I have no link with any of the above sites, and I advise double checking any information or calculation given by them.

Kev.


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## clodhopper2006 (Aug 13, 2006)

Be a bit careful with these wire calculators. There are many factors you have to apply that are not considered and these make a big difference to the correct cable selection.

Factors often not included are:

ambient temp
instalation method (clipped to surface, conduit etc)
any thermal insulation in the route.
grouping
volt drop

To name just a few.

http://www.bellissimalingerie.com/catalogue/brasize.asp

That one was facinating though 

Bob


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## Pudsey_Bear (Sep 25, 2008)

It's a minefield, I'm still trying to work out the cables I need, as it appears the ones I have are not up to the job, but no one seems to be able to give me a cable size so far, I thought it was quite straight forward, but would appear not to be so.

Glad you found one you liked though.

Kev.


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## clodhopper2006 (Aug 13, 2006)

Kev_n_Liz said:


> It's a minefield, I'm still trying to work out the cables I need, as it appears the ones I have are not up to the job, but no one seems to be able to give me a cable size so far, I thought it was quite straight forward, but would appear not to be so.
> 
> Glad you found one you liked though.
> 
> Kev.


What is it you're doing Kev? Tell me about the circuit. What is the overcurrent device going to be(fuse or breaker)? What is the equipment you're supplying (important as diversity may apply)? What wattage is the load? Describe the cable route ie how the cables are concealed and ambient temp. Will the cables be by themselves or grouped. If grouped with how many? What is the cable type (copper, single core, twin/earth etc)?


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## Pudsey_Bear (Sep 25, 2008)

Hi bob,

*Overcurrent device*
is going to be a fuse, but not sure of the size.

*Equipment I'm supplying*
will be an inverter initially to power just TV, DVD, a coffee grinder, plans possibly include a small microwave and an electric percolator rated at 300 watts. possibly a low powered toaster

*Wattage load*
up to 1000watts I should think, I'm trying not to take more electric gubbins that I need, and won't be using them all at the same time

*Cable route and how the cables are concealed*
as short as possible, down to the bottom of the seat bases, then under a section of floor, which is not sealed, I could run them down through the floor I suppose, which would assist in keeping the temp down.

*Ambient temp*
not a clue, but oven is immediately behind front seats, however, I don't think I'd be using much if any current whilst using the oven, otherwise, I'd say 18 to 24 degrees at head height, not sure about floor level.

*Will the cables be by themselves or grouped. If grouped with how many?*
I assume just two to connect the batteries plus two more for the inverter. so I would prefer four single cables, not as neat but easier to route and fit.

*What is the cable type* 
hopefully copper singles.

That got my brain going.

Thanks for asking questions that make sense, even to me.

Kev.

PS I currently have already 1 x 16mm2 and 1 x 20mm2 cables, these were purchased to connect the two batteries,
I intend to fuse all cables, inc negs and for batt to batt, but not sure what fuse rating to use, some one suggested getting a small consumer unit and fitting breakers, but that's out of my budget at the mo, but sounds like a reasonable idea to me.


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## CliveMott (Mar 10, 2008)

More directly Motorhome related oddments here.

http://www.motts.org/MOTORHOMES.htm

If there are any other topics that I should add please say so and I will do my best.

Clive


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## Fatalhud (Mar 3, 2006)

Kev_n_Liz said:


> It's a minefield, I'm still trying to work out the cables I need, as it appears the ones I have are not up to the job, but no one seems to be able to give me a cable size so far, I thought it was quite straight forward, but would appear not to be so.
> 
> Glad you found one you liked though.
> 
> Kev.


That's because people were trying to steer you in the right direction but you blanked there suggestions as you said your experts knew best, Plus one minute you where quoting 2.2kw inverter then a few posts later it went down to 1.1kw

http://www.motorhomefacts.com/ftopic-65016-days0-orderasc-10.html

Alan H


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## pippin (Nov 15, 2007)

http://www.bellissimalingerie.com/catalogue/brasize.asp

_Under *wire* digging in _

Not entirely off-topic!

Incidentally, whenever I have calculated low voltage (and therefore usually high-current and voltage drop significant) wire sizes I have invariably gone for the next size up to that given by the calculation.


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## clodhopper2006 (Aug 13, 2006)

Hi Kev just need to check a point with you. Do you know that 1000w is going to pull 83A from your battery?

Bob


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## Fatalhud (Mar 3, 2006)

No problem Bob It didn't phase him when I told him 2.2kw was going to pull around 180amp :twisted: :twisted: 

Alan H


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## pippin (Nov 15, 2007)

Falathud - nice technical typo there:

_It didn't *phase* him when I told him 2.2kw _

I assume the circuit will be single *faze*?!!!!!!!!


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## Fatalhud (Mar 3, 2006)

I'm even funny went I don't mean to be 8O 8O 8O 

Alan H


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## clodhopper2006 (Aug 13, 2006)

Fatalhud said:


> No problem Bob It didn't phase him when I told him 2.2kw was going to pull around 180amp :twisted: :twisted:
> 
> Alan H


Right then to answer Kev

I've had a look at table 4D1A in BS7671/2008 method B assumed. Now 25mm2 will carry the 83A however volt drop would exceed 6% and so would not be recomended. The next size up is 35mm2 and as no other rating factors make any significant difference in this case then this is the correct cable to use.
35mm2 cable carries a maximum of 125A so you may use overcurrent protection of any amperage you like so long as it is higher than the load current 83A and less than the cable rated current 125A

NOTE: You will need good quality batteries ie with low internal resistance or you may find when you draw a heavy load your voltage falls off sharply and your inverter will shut down.

Bob


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## Pudsey_Bear (Sep 25, 2008)

I'd happily, take advice from you, once you all say the same thing, I posted the link to the inverter, but you only saw it as a 1100 when it's clearly a 1100/2200 surge, is it my fault that some don't read and others give conflicting advice, and also ask questions I haven't a clue how to answer, is it any wonder I don't know who's advice to take.

Bob today asked clear concise questions, which I answered to the best of my ability, he now has another and again I'll give any information I have.

I wasn't sure exactly how many amps it would pull as I've not seen it as a figure which makes sense to me, IE Fatalhud said "2.2kw was going to pull around 180amp" is that per minute, hour or what, there is no point in giving half the information is there, it's not as if I'm standing up and saying I know it all, if you give info to someone give it all, not half of it, if it's going to use 180amps in an hour at 2200watts so what, that's a surge of 2200watts, I'm not going to at that for an hour, only a few seconds.

The boffins in the know I mentioned in the crimper post, were the people who are supplying the inverter, who it turns out had asked the manufacturers, who's credentials, I did not question, would you?

As for Clive comments, if your info was so good, why didn't you say so in reply to the two very polite PM's I've sent to you over the last few days, no you though,t he doesn't know what he's talking about I'll ignore him, which is fine, but don't come on here playing clever, as it's not very impressive.

If you want to help someone, then take a look at the way Bob is trying to help me, he asked specific questions, and got as near specific answers as I could give, not difficult to do, it just takes a little patience and understanding, but if you just want to be clever, well that's really hard isn't it.

I've learned a lot from some of you on here, and I've been grateful for the chance to pass some of it on to other newbies, in my view that's what this site is about, and we have a laugh of course, but I don't take the mickey out of people just because they are ignorant of some of the finer points of a topic, I might sometimes take a friendly poke at someone, who says something daft, as we all do sometimes, but only in fun, and it's usually obvious, and I have had the odd member make some comical comment when I've screwed up.

But today, a few of you have taken it upon yourselves to try and ridicule me, for what, just because I maybe being a bit over cautious about something which could be potentially life threatening, or at least setting fire to my motorhome, by making sure that I got the right information well shame on you, I hope it made you feel good, because it certainly made me see that some people are just not worth a light.

To answer your question Bob, no I didn't know it drew 83amps, the figure which was previously given was 180amps for 2200watts, so assumed it would be half at 90 amps, this is what I meant about conflicting figures, not a huge numerical difference true, but electrically it seem a lot at 7amps, incidentally, could you tell me just what 83amps actually means in real terms, as it doesn't mean a great deal at the moments.

Thanks again Bob.

Kev.


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## Pudsey_Bear (Sep 25, 2008)

Hi Bob,

So 35mm2 cable which is good for a 125amp loading, so a fuse of around 90 to 100amps would be OK then, or as you say in my words 83 to 125 amps fusing, to be fair I remember someone suggesting 35mm cable, but other suggested bigger others smaller.

If I might ask, what sort of fuses would be best as my knowledge of fuses stops at about a 30amp blade type, or std domestic stuff, so have no idea of where to get they sizes you reccomend.

Thanks again Bob.


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## pippin (Nov 15, 2007)

Sorry Kev, but I wonder if you should be tackling this work on your own at all, even with assistance of members here on MHF.

My father used to say "the importance of any question lies in the consequences of getting the *answer wrong*"

None of us who are qualified to actually do this sort of work can know all the precise details of what is required - there is simply not enough information available to us.

If we had your van in front of us and all the specifications of all the equipment then we could specify exactly what is required and also how to do it.

We don't, so we can't, other than to best guess and give general guidance, with the usual disclaimers.

Some of the information seems to be scattered across more than one thread, which makes things even more difficult for us.

You wrote, in answer to a helpful reply:
_"2.2kw was going to pull around 180amp" *is that per minute, hour or what*_
Well, that will have made every one of us with knowledge of electrical 
theory just cringe.
There is such a fundamental difference between amperes and ampere hours that it has us all wondering if we should even be advising you on how to approach the job rather than suggesting that you get the work done by a professional.

Harsh words, I know, but said with the best intent - with your safety in mind. 
Left unsaid, well it might result in you doing something that sets your van on fire.

E&OE


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## clodhopper2006 (Aug 13, 2006)

Kev_n_Liz said:


> Hi Bob,
> 
> So 35mm2 cable which is good for a 125amp loading, so a fuse of around 90 to 100amps would be OK then, or as you say in my words 83 to 125 amps fusing, to be fair I remember someone suggesting 35mm cable, but other suggested bigger others smaller.
> 
> ...


Hi Kev,

To help your understanding, amps are the engineering unit for the measurement of the flow of electical charge (current). In other words if you have a tube station with a full platform (battery) and the train comes along. The doors will open (switch) and a given number people will be able to enter until either the train is full or the station is empty.
You can think of the platform as being the positive and the train as being negative. The flow rate of people you can think of as current (amps) and this is dependent on how much they are pushing (volts) and the resistance/impedance caused by the crush in the doors (ohms).
So a current flow of 83A is a constant if the resistance and voltage stay the same (leaving asside an initial inrush). An Amp hour is a flow of a given current for one hour so a 100A/h battery will deliver 83A for just over an hour and would then be flat.
Power is the current in amps multiplied by the voltage so if you know the power and the voltage you can work out the current. In this case 1000w divided by 12v = 83A. The other value of 2200w again divided by 12 = 183A.
Fuses are available from elctrical suppliers such as RS Components. Here's an example of a fuse that would meet your needs.

http://uk.rs-online.com/web/search/...&binCount=103&selectAttribute=100A#breadCrumb

Cheers,

Bob


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## Pudsey_Bear (Sep 25, 2008)

pippin said:


> Sorry Kev, but I wonder if you should be tackling this work on your own at all, even with assistance of members here on MHF.
> 
> My father used to say "the importance of any question lies in the consequences of getting the *answer wrong*"
> 
> ...


Thanks for that Pippin, and I do appreciate the sentiments with which you said, and I do understand, but there are always going to be variables.

If I had the money I would get this done by a professional, but from where I'm sitting, that is just not possible hence me wanting to go a little over the top, IE when doing my solar panel I have gone to 5mm2 cable, not 4mm as a precaution, I have got smaller fuses in than recommended, to be on the safe side, so I take none of this lightly, I fully realise the harm that could be caused, by a silly mistake, honest I do, I made one this morning, it was called getting up, but it's the way I am I guess, I assemble as much info as possible, then I act on it as I did with my solar panel, it's in it's working, it's safe.

I appreciate with the battery/inverter job the currents are much higher, which is the reason for the caution, and I will have to do it myself, as I have no option.

I'm sorry I made you cringe with my amps query, :lol: but to a non sparky, it doesn't actually say much, however from your response I might make a best guess, but would still like to have it confirmed , that 180amps is just that if I use 2.2kw I will be using 180amps at the same time continuously until I stop using 2.2kw, so would I be using 90amps if I drop to 1.1kw?

It is through the knowledge of others that I learn, I was sh1te at skool, but I've been on a school of life since then as I like to learn, but reading is a real chore for me, I read Ok and my spelling is Ok most of the time, but I do seem to have some difficulties picking some stuff up, and I'm largely a monkey see monkey do kind of learner, but I am slowly getting to grips with the terminology of these jobs, and I am getting there always erring on the side of caution, If I'm not certain of something I come and ask someone, I may be a bit dim on some stuff, but stupid I ain't.

I've learned a lot today, best thing I learned today was think before you put the wires from a solar panel in your mouth to lubricate it before pushing it through a grommet, dumb or what, in my defence I'd already done it with dead wires, but the grommet slipped through the hole, and the panel was upside down then, but this time it was in glorious sunshine, fortunately on a 40watt panel, I learned a lot from that.   

Kev.


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## Fatalhud (Mar 3, 2006)

Kev_n_Liz said:


> I'd happily, take advice from you, once you all say the same thing, I posted the link to the inverter, but you only saw it as a 1100 when it's clearly a 1100/2200 surge, is it my fault that some don't read and others give conflicting advice, and also ask questions I haven't a clue how to answer, is it any wonder I don't know who's advice to take.
> 
> Bob today asked clear concise questions, which I answered to the best of my ability, he now has another and again I'll give any information I have.
> 
> ...


It was you who quoted the inverter as 2200watt which I said would need around 50mm/2 cable, Then about 4 posts later you posted a link then said it was 1100watt

It is you that keep giving different information,

In this link you are now saying it has a load of 1000watt

If you want the correct answer stop moving the goal posts and stop getting arsey with others because you don't know what your on about

In my post on the other thread I was all the time trying to put you off the route you where taking, 
You say you where being over cautious, Using a blow torch in the confines of a small box filled with batteries is not over cautious,
People tried to steer you in the right direction using the differing information being given, But they are not your boss so cannot simply say STOP don't do that

Thankfully Bob has stepped in to help you, as I know from previous posts on Electrical issues his knowledge on the regs and good working practices are far better than mine and most others on this forum , Although I'm not sure about the Train mallarky

Alan H

ps can we swap dummies yet :?


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## Pudsey_Bear (Sep 25, 2008)

Alan.

Gizakiss.

Kev.


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## pippin (Nov 15, 2007)

Glad you took it on the chin Kev, none of it was meant in a nasty sort of way.

Your "experiment" with the solar panel wires in your mouth reminds me of an old saying:

"It's volts that jolt but mills (milliamperes) that kills."

25,000V with microamps available (due to a high resistance source) will not kill - unless the jolt sends you backwards off the ladder!

However, try to do that with just 240V with the full might of the national grid behind them will kill.

In fact anything above 55V(ish) is dodgy.

Anything above 30mA(ish) is dodgy.

Below both of those and you will likely survive, above the odds are you won't.

Well, you might with AC but definitely not with DC.

Keep on asking away - eventually you will get there!


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## Pudsey_Bear (Sep 25, 2008)

Oh no,. not Thomas the tank engine Bob, please.

I'm thinking either

BF2 miniature fuse link,100A 32Vdc

or 

BF1 miniature fuse link,100A 32Vdc

I'd rather go for the CF8 battery fuse link,100A 48Vdc the Battery pole one but just not sufficient height to get it in unfortunately.

I notice they're 32volts dc, I assume that's Ok for me to use.

Thank you very much Bob for your patience, kindness and understanding, and the remarkable way you have of getting and giving information, you should teach this stuff.

Kev.


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## Fatalhud (Mar 3, 2006)

Kev_n_Liz said:


> Alan.
> 
> Gizakiss.
> 
> Kev.


No tongues


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## pippin (Nov 15, 2007)

32V is OK - that is the maximum voltage that can appear across the terminals of the fuse when it has blown.

Higher voltages could arc across even when the fuse has blown.


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## Pudsey_Bear (Sep 25, 2008)

I just didn't think, famous last words, hence the amount of thought with this one.

Just looking at the fuses Bob recommended, They look like good gear, but the dims don't look very huge 29mm high	67.3mm overall height	16.3mm widf

Kev.


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## Pudsey_Bear (Sep 25, 2008)

Yes I read the spec, and sussed that bit out.

current (get it) job is to determine all the various dimensions of all 4 cables batt to batt and inverter to batt.


That's the easy bit, although it would be a lot easier if the damn battery terminal clamps were all the same thread size for the ring terminals. one size on 1 batt, but 2 on the other. grr, still I'll get there in the end, I think, thanks for your help too pippin, watch out for them sheep, saw some cute lambs on Arran, they'd have taken your breath away.  

Kev.


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## Fatalhud (Mar 3, 2006)

Just be aware Kev that if you order from RS you have to order a minimum of 5

Alan H


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## bigbazza (Mar 6, 2008)

I'm definately not getting involved with this thread but I just wondered which tact and diplomacy school did you pass out from Kev?


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## Pudsey_Bear (Sep 25, 2008)

Good evening Bigbazza.

Have you come to contribute anything useful? hope so.

Kev.


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## Pudsey_Bear (Sep 25, 2008)

Bob, Alan, Fatalhud,

These fuses I understand it's a packet of 5 (used to be three when I was a lad)   anyway, these fuses, just one point I'm not to clear on, obviously I'll need to fuse the positive between the two batteries, and also the positive from the inverter, but will they both need to be 100amp ?? :? :? just so I don't have to trail down to RS twice.

Also, I can't find who said it now, but I was advised to run the positive inverter cable to one battery, and the neg to the other to spread the load, but someone else said I didn't need to, I don't care which as the difference is 1 mtr of cable, but if there is some advantage, I'd like to use it, any ideas anyone.

I found the post 


Camoyboy said:


> When 2 batteries are connected together, it is best to both charge and draw current equally from both. Therefore it is best to connect to the + on one battery and the - on the other.


Kev.


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## clodhopper2006 (Aug 13, 2006)

Kev_n_Liz said:


> Bob, Alan, Fatalhud,
> 
> These fuses I understand it's a packet of 5 (used to be three when I was a lad)   anyway, these fuses, just one point I'm not to clear on, obviously I'll need to fuse the positive between the two batteries, and also the positive from the inverter, but will they both need to be 100amp ?? :? :? just so I don't have to trail down to RS twice.
> 
> ...


No Kev the output from the inverter will be 230V I would have thought the inverter would have it's own inbuilt protection for over current. If not you again do the calc. P/V so 1000/ 230 =4.33A. Thats your output current so a fuse just larger than that is required.

Also when two batteries are connected in parallel then the + on both batteries are electrically the same so it makes absolutely no difference which one you connect to. Same goes for the -

Bob


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## Zebedee (Oct 3, 2007)

clodhopper2006 said:


> P/V so 1000/ 230 =4.33A. Thats your output current so a fuse just larger than that is required.
> Bob


Glad you said that Bob.

I was beginning to think I had completely lost the plot when I read "_100 Amp fuse_".

I don't think I'd want one of those anywhere near my truck!!!! 8O 8O

(I was still working on 2kw (Dohh), which would suggest a 10amp fuse.)

Dave


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## Fatalhud (Mar 3, 2006)

I think Kev is still talking about the 12v side

In my van the 2 batteries are next to each other so there is very little chance of a short circuit
I think Kevs batteries are under driver and passenger seats about 1m apart, so it may be worth protecting the link cable against short circuit

When Kev said the positive from the inverter, I took it that he meant the 12v cable feeding the inverter

Alan H


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## Zebedee (Oct 3, 2007)

Hi Alan

You think *you're *confused by this thread! 8O 8O 8O

I think I need to go and let me brain cool down!!

Dave


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## clodhopper2006 (Aug 13, 2006)

Fatalhud said:


> I think Kev is still talking about the 12v side
> 
> In my van the 2 batteries are next to each other so there is very little chance of a short circuit
> I think Kevs batteries are under driver and passenger seats about 1m apart, so it may be worth protecting the link cable against short circuit
> ...


Yes I see. I saw the word "from" and translated to "output" . If it's a meter apart I'd be inclined to bung one of your fuses in there too. May as well as you'll have five. Generally though if the batteries are close together there's no need to bother fusing the wire between the battery. Basically what your doing is protecting the wire with the fuse, nothing else so use your judgement to decide if the wire might get damaged. If so then fuse it.

Bob


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## Pudsey_Bear (Sep 25, 2008)

It's so easy to be confused innit, and you lot know yore stuff (I hope) :lol: :lol: :lol:



Kev_n_Liz said:


> obviously I'll need to fuse the positive between the two batteries, and also the positive from the inverter, but will they both need to be 100amp ?? just so I don't have to trail down to RS twice.


I'll ask again, without complicating it this time.

I need a 100amp fuse to protect the batteries from short circuit as they're going through the floor. yes or no

I need a 100amp fuse on the 12v side of the inverter. yes or no.

Kev.


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## clodhopper2006 (Aug 13, 2006)

Kev_n_Liz said:


> It's so easy to be confused innit, and you lot know yore stuff (I hope) :lol: :lol: :lol:
> 
> 
> 
> ...


Kev you should know by now things are never that simple 

Your 100A fuse is not to protect the battery from short circuit, it is to stop the 35mm sq cable melting or catching fire in the event of a short circuit. So yes you need a fuse between the battery and the load irrespective of whether the wire goes through the floor or not. You don't need another fuse at the inverter end of the 35mm sq cable.
If you have two batteries in parallel and they are seperated by more than a foot or so you need another 100A fuse between the two batteries to protect this cable too. If they are close together you don't need a fuse between the two positives at all.

Bob


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## Fatalhud (Mar 3, 2006)

Bob, do you not think that there should be a fuse at each battery protecting the link cable 

Alan H


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## clodhopper2006 (Aug 13, 2006)

No you only need one and then only if it's mor than a foot or so apart


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## Fatalhud (Mar 3, 2006)

clodhopper2006 said:


> No you only need one and then only if it's mor than a foot or so apart


But that leaves 1 battery unprotected
You cant count on the fuse protecting the inverter because that would mean the inverter is then protected by 2 fuses in parallel giving a much higher fuse rating

See crap drawing for how I think it should be

Alan H


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## clodhopper2006 (Aug 13, 2006)

let me emphasise this point.

The job of the fuse is NOT to protect the battery. The battery can look after itself and can deliver far in excess of 100A if it needs too.

the fuse is to protect the wiring and nothing else. One fuse on the wire between the batteries will protect that wire from burning in the event of a short between the wire and earth. If they are so close together so that they will not short then no fuse is needed between the batteries 

the inline fuse between the battery and the inverter covers this wire.

neither fuse protects the battery only the wiring nor does it protect the load


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## Fatalhud (Mar 3, 2006)

Yes I know it is to protect the cable (used the wrong term to explain my point)
The link cable is connected to the + of both batteries
How can you protect the cable against short circuit with 1 fuse
where do you put the fuse
If the cable had a fault you need to be able to isolate both ends

Where's Frank when you need him :? 

Alan H


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## clodhopper2006 (Aug 13, 2006)

Fatalhud said:


> Yes I know it is to protect the cable (used the wrong term to explain my point)
> The link cable is connected to the + of both batteries
> How can you protect the cable against short circuit with 1 fuse
> where do you put the fuse
> ...


Yes I see what your saying. If either end was groundedit could draw current from either battery so yes point conceded.


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## Fatalhud (Mar 3, 2006)

I knew what I was trying to say but i'm crap at putting it into words

Are you still with us Kev   

Alan H


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## Pudsey_Bear (Sep 25, 2008)

This is why I get confused, I now have two people, who seem to know this stuff, and you two end up having to discuss the finer points of if a fuse is even needed.

I've read and re-read the last few posts and come up with the following.

The fuse is a simple device to stop the wiring becoming an electric heater by placing a lighter wire in the electrical path, that bit is a huge simplification, but a good illustration of the purpose of a fuse I think.

I need to place a 100amp fuse in the positive lead in the batt to batt link.

I need to place a 100amp fuse in the positive lead in the batt to Inverter link.

The fuses in the Inverter itself 3 x ???amp will protect the inverter from overloading from appliances plugged into it.

For Freds sake, please say that's what you have been saying, I understand when it's put simply, put i can't be sure when you get all tech with equations n stuff although P/V is OK that means Petrol/Velocity dunnit.

Kev.


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## Pudsey_Bear (Sep 25, 2008)

Fatalhud said:


> Yes I know it is to protect the cable (used the wrong term to explain my point)
> The link cable is connected to the + of both batteries
> How can you protect the cable against short circuit with 1 fuse
> where do you put the fuse
> ...


I see, (I think) if the S/C occurs between the pos pole and the chassis, but here is no fuse in that portion, we have an electric heater, so if that's true, it would make sense to have a fused link as close as possible to each pos pole on each battery. not a problem as I'll have some to spare.

Kev.

PS, Sorry Bob, I answered Alans post before reading on, so I didn't know you had concurred.


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## Fatalhud (Mar 3, 2006)

Hi Kev
click on the crap drawing I did a few posts earlier this is what you want

3 fuses
One at each end of your battery link as close to the batteries as possible and 1 as close to a battery for the feed to the inverter

The trouble is you stick a few blokes in a room and show them a job, each one will come up with a different way of achieving it, It doesn't mean 1 of them is wrong its just how they interparate what the person wants with the info given

The next issue will be cable size

I would advise you use the same size cable throughout the job
If the inverter has 35mm tails then that is the size I would use

I prefer to use Tri-rated cables for this type of job because they are very flexible, Solid cables could be prone to snapping because of all the vibration going on in a motor home, plus Tri-rated is easier to work with

Never use domestic twin and earth cables in a motor home for this reason

Alan H


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## Pudsey_Bear (Sep 25, 2008)

Maybe this will show how I think it should be done, see drawing, just a quickie nowt special.

Click it to make it more readable.


Kev.

PS Thanks for the help.


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## Fatalhud (Mar 3, 2006)

Looks good to me

Not as good as my drawing though :wink: 

Crimp them don't sweat them (solder)
If your torch does not get the joint really hot really fast then the heat will dissipate up the cable with a good chance of it damaging the insulation and also if you get a dry joint with those high currants you could be in right trouble

"in my opinion"
Alan H


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## Zebedee (Oct 3, 2007)

Stone me Kev - there must be an easier way! 8O 8O 8O

_*(And don't get stroppy with me. This is not a criticism - just an alternative way of meeting your needs!   )*_

You want to rig up an inverter to power, " _just TV, DVD, a coffee grinder, plans possibly include a small microwave and an electric percolator rated at 300 watts. possibly a low powered toaster_"

This is not the advice you are looking for (obviously :roll: ) but it does sometimes pay to step back and ask yourself some very fundamental questions. It's so easy to get one idea fixed in your mind and ignore the other possibilities. :? 

The TV/DVD is easy - use a 12 volt one.

Hand powered coffee grinders are cheap, and look quite decorative on the work surface. They also grind better than some electric ones as the size of the grounds is far more even.

The microwave is not so easy, but 12 volt ones do exist, if you can't live without one. :?

Those hexagonal shaped Italian coffee percolators that go on the gas ring are almost standard fittings in Italian caravans and motorhomes - and there has to be a reason why they are so popular. :wink:

Making the toast - under the grill, or one of those little gadgets that sit on the gas ring. Have never used one, but people on here say they are brilliant.

Just a few random thoughts.

Dave


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## pippin (Nov 15, 2007)

Zebedee/Dave - those were my exact thoughts about a hundred posts ago, but I didn't think to post them!

If we all charged just the minimum wage for the time we have spent giving advice to Kev, well it would have been far cheaper for him to have got it done professionally in the first place!

Mark you, I am pleased to have got the part numbers of those 100A fuses ((and I have an RS account!) because I am fitting a second battery which will need appropriate fusing.


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## Fatalhud (Mar 3, 2006)

Totally agree with you Dave
I posted a few days ago about the power used by the 1.6kw inverter fitted in my van

It was installed as part of the Air con but seamed rude not to use it to power other items as we would not need air con very often

After discovering the extra power needed to run the big inverter I installed my old 300watt from my old van

http://www.motorhomefacts.com/ftopict-65158-.html

Alan H


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## Pudsey_Bear (Sep 25, 2008)

Zebedee said:


> You want to rig up an inverter to power, " _just TV, DVD, a coffee grinder, plans possibly include a small microwave and an electric percolator rated at 300 watts. possibly a low powered toaster_"
> 
> This is not the advice you are looking for (obviously :roll: ) but it does sometimes pay to step back and ask yourself some very fundamental questions. It's so easy to get one idea fixed in your mind and ignore the other possibilities. :?
> 
> ...


You're absolutely Right Dave, and this has been considered and in fact some have been done already, and as you well know I don't do stroppy, I reply in earnest. :lol: :lol: :lol:

We have a hand grinder, it makes nice grounds but is a chore, and messy, even if we're careful, getting a small leccy one.

We have a 12v hair dryer, it's rubbish but Does the job eventually

We got one of those coffee percs you mention, sorry but it's going in the bin, not had any decent coffee out of it, and it's bloody dangerous, if anyone wants it, it's yours, we have an old fashioned one which works better, but is too small, so needs replacing anyway.

We have a Smev oven, toast takes so long you forget it's in there and becomes a cinder, so need electric one, and yes we've tried the gadgets to use on the hob.

Microwave on 12v, may as well put food down me pants, so 230v needed.

12v TV is sometimes OK sometimes not, lot's of white noise etc, works OK on the little inverter, but the little inverter not big enough to run DVD player at the same time.

When I get time I'm disconnecting or maybe using a switch to connect all the sockets in the MH to run from the inverter, instead of the EHU side, as we don't use EHU, this will also have the advantage of not having wires running all over the place, as the previous owner fitted sockets in sensible places, unlike Laika who only fitted one

And although as you say it's not the answer I was looking for I thank you for putting it out there as it'll help others as well, as has the Fuse link to RS for Pippin.

I sometimes ask daft questions as do we all, but there will always be someone to say, oooh you don't want to be doing that, and remember, not everyone post a question, some just search and use the advice given.

Kev.


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## Zebedee (Oct 3, 2007)

Kev_n_Liz said:


> I thank you for putting it out there as it'll help others as well, as has the Fuse link to RS for Pippin.


That was part of the reason for posting it Kev. We are all here to help each other.  



Kev_n_Liz said:


> I sometimes ask daft questions as do we all, but there will always be someone to say, *oooh you don't want to be doing that*, and remember, not everyone post a question, some just search and use the advice given.
> Kev.


Which again is why I was careful not to be critical. 

It often helps to receive an alternative view - even if you've already considered it, or just plain don't agree.

I've had my mind changed a number of times by reading about what someone else suggests, different to my plans. :wink:

Great forum innit!!

Dave


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## Pudsey_Bear (Sep 25, 2008)

The biggest problems as far as I can tell with this type of post is, the reader needs to read the whole thread, and imperatively any links as well as the links give extra info, before posting a reply, but we are sometimes a bit lazy and skim the surface of the post, and get the wrong impression, I do it, you do it, we all do it.

Kev.


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## clodhopper2006 (Aug 13, 2006)

Can't fault your crap drawing Kev


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## Pudsey_Bear (Sep 25, 2008)

I love to do them, odd really as I was crap at tech drawing at skoooll.

Can't use cad though, I did that in publisher, very limiting, but it helped me see the layout so I didn't forget anything and it might prove useful for other peeps.

Kev.


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