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2007 Fiat Ducato Ace Siena 2.2 100 Multijet, Keighley, Still in Gods County.
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Discussion Starter · #1 ·
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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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 :D

Bob
 

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2007 Fiat Ducato Ace Siena 2.2 100 Multijet, Keighley, Still in Gods County.
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Discussion Starter · #3 ·
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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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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2007 Fiat Ducato Ace Siena 2.2 100 Multijet, Keighley, Still in Gods County.
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Discussion Starter · #5 ·
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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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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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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Discussion Starter · #14 ·
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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Discussion Starter · #15 ·
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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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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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.

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.
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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Discussion Starter · #18 ·
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"

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
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. :oops: :oops: :oops:

Kev.
 

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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.

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.
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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