Digital multi meter

cruisaderhilton · Senior Member

Digital multi meter

Old Col · Veteran Member

cruisaderhilton wrote:
n to see what state the old element was in ,, I want to check mine just as an interest but don't know what setting to put my multi meter, can someone tell me what position to set it .And yes I will disconnect the caravan from the 240v power lead before doing any work Thankyou.

only two states working or not working

if you do not know how to use a multi meter leave the 240 volt alone

Ondabeach · Senior Member

Hi Cruisader. If the element is kaput, it will be open circuit, which means you'll get no reading at all. If you get a low resistance reading, something in the order of 10 ohms approximately, then it's probably OK.

Disconnect the power!!!

Set your meter to the 200 ohm range, directly opposite the off position and put the leads on the element ends.

Here's a YouTube video of how to do it. The heater he's checking has 2 elements, just ignore the second one.

https://www.youtube.com/watch?v=XaDYpKvCSQ4

-- Edited by Ondabeach on Monday 15th of June 2015 01:12:21 PM

hako · Guru

I was going to post a simple english explanation on how to do this but decided against as I don't want aggro that would follow it. My suggestion is Google "how to use a multimeter for simple checks" and go from there otherwise you'll wish you never posted. There are some very simple lessons on there. Sorry.
Good Luck.

exa41 · Guru

you need a Megger not a Multimeter, because I multimeter is not sensitive enough to do insulation tests.

Phil C · Guru

Hi.

If you wish to read the state of your element the best I can think of is to use the 2M ohm position and have the black lead in common and the red in the socket to its right (volts ohms etc.) DO NOT use the amp socket.

RULES FOR YOUR PROTECTION do these first....

1. ENSURE ALL 240 is switched off by disconnecting your caravan from the mains at the entry point.
2. Disconnect the power leads from the element, there may be control circuits in parallel that will muddle the reading.
3. If there is an OL (overload) displayed you MAY have a blown element, decrease each step downwards in the ohms scale, if it is still OL its blown. If you get a reading on the low scales and you are not blowing the breaker inside the element may be OK, get a sparky to check the insulation resistance with a megger
3. Check the 240V TWICE at least before you play with this, if you are in the slightest doubt, call a sparky.

I know you have said you will disconnect the 240V, but Im a retired electrical trade teacher so im permitted to nag. Take care.
Cheers

Cloak · Guru

I'm with Hako

Silence is golden and stress free.

PeterD · Guru

The safe way to check quickly is to pull the HWS system plug out of the socket. If you remember to do that after disconnecting the power to the van it is perfectly safe. Then follow the method in the Youtube video link above. If you need it replaced then get an electrician to do it. If the element is OK then put the meter across the active and neutral pins on the plug. This will check the switching and the thermostat, again get a licensed tradesman to repair that. If that is OK then the problem is in the van wiring. By now you should know who to call.

03_Troopy · Guru

exa41 wrote:
you need a Megger not a Multimeter, because I multimeter is not sensitive enough to do insulation tests.

He needs to do a continuity check, not an insulation check. As has been already posted, use the resistance function in the 200 Ohms range.

oldtrack123 · Guru

03_Troopy wrote:
exa41 wrote:
you need a Megger not a Multimeter, because I multimeter is not sensitive enough to do insulation tests.
He needs to do a continuity check, not an insulation check. As has been already posted, use the resistance function in the 200 Ohms range.

Hi

Ditto

Plus, a megger in inexperienced hands can do a lot of damage, to possible electronic components . biggrin

PeterQ

03_Troopy · Guru

oldtrack123 wrote:
03_Troopy wrote:
exa41 wrote:
you need a Megger not a Multimeter, because I multimeter is not sensitive enough to do insulation tests.
He needs to do a continuity check, not an insulation check. As has been already posted, use the resistance function in the 200 Ohms range.
Hi
Ditto
Plus, a megger in inexperienced hands can do a lot of damage, to possible electronic components .
PeterQ

But they can also be a lot of fun when used on the unwary

oldtrack123 · Guru

03_Troopy wrote:

.
Hi
Ditto
Plus, a megger in inexperienced hands can do a lot of damage, to possible electronic components .
PeterQ

But they can also be a lot of fun when used on the unwary

Hi troopy

Did I say OOOOUCH biggrin

03_Troopy · Guru

Incidentally Peter, did you know the "Megger" brand also produce low resistance ohm meters, just to throw a bit of confusion into the mix. We used to use one for Ground post and electrical bonding testing on aircraft.

oldtrack123 · Guru

03_Troopy wrote:
Incidentally Peter, did you know the "Megger" brand also produce low resistance ohm meters, just to throw a bit of confusion into the mix. We used to use one for Ground post and electrical bonding testing on aircraft.

Hi Troopy

Yes smile

Even the old one's from 1940s had a low ohm scale my poor old memery lowest reading was 0.01 Ohms,

By the way was it you who left that big capacitor laying on the table?? biggrin

PeterQ

-- Edited by oldtrack123 on Friday 26th of June 2015 12:09:14 PM

oldtrack123 · Guru

exa41 wrote:
you need a Megger not a Multimeter, because I multimeter is not sensitive enough to do insulation tests.

HI

Any multi meter can do a LOW voltage insulation test well into the megOhm range

But Mains voltage insulation testing is required be carried out at a high voltage[ 500V DC min]

The higher voltage is required to put some" stress" on the insulation.

But beware when doing such tests on equipment other than simple wiring, motors etc

In this day of electronics being in almost every thing, that voltage could cause damage & permanent failure .

PeterQ

03_Troopy · Guru

the new ones have a resolution as low as 0.1 of a micro ohm. Another thing we used them for was to make sure all the anodise was removed from aircraft framework before NDI testing. Can't be 100% sure, but I think we had to have something like less than 0.002 milliohm from point to point on the metal surface per cm.

Phil C · Guru

When I was testing earth points in the RAAF we used a milli ohm meter, heaps expensive and not very easy to use. If I remember the lowest was one milli ohm. It used a Wheatstone bridge and we had to calculate the resistor x. Which of course was the earth point. Correct me if I'm wrong.

When I was in the PMG PeterQ we did the capacitor trick with a 100000uf capacitor at 50 volts. The instructor was a bit peeved that day he got a little thump.

Cheers

03_Troopy · Guru

Phil C wrote:
When I was testing earth points in the RAAF we used a milli ohm meter, heaps expensive and not very easy to use. If I remember the lowest was one milli ohm. It used a Wheatstone bridge and we had to calculate the resistor x. Which of course was the earth point. Correct me if I'm wrong.

When I was in the PMG PeterQ we did the capacitor trick with a 100000uf capacitor at 50 volts. The instructor was a bit peeved that day he got a little thump.

Cheers

Capacitors can be a bit of a bugger eh Phil? When I worked on F-111 radar gear back at Amberley in the late 70's, we used to repair a particular HVPS. They could sit on a shelf in the storeroom for a week or two and still give you a nasty bite when you put a finger on the BIG caps in them.

dorian · Guru

Phil C wrote:
Hi.

If you wish to read the state of your element the best I can think of is to use the 2M ohm position and have the black lead in common and the red in the socket to its right (volts ohms etc.) DO NOT use the amp socket.

RULES FOR YOUR PROTECTION do these first....

1. ENSURE ALL 240 is switched off by disconnecting your caravan from the mains at the entry point.
2. Disconnect the power leads from the element, there may be control circuits in parallel that will muddle the reading.
3. If there is an OL (overload) displayed you MAY have a blown element, decrease each step downwards in the ohms scale, if it is still OL its blown. If you get a reading on the low scales and you are not blowing the breaker inside the element may be OK, get a sparky to check the insulation resistance with a megger
3. Check the 240V TWICE at least before you play with this, if you are in the slightest doubt, call a sparky.

I know you have said you will disconnect the 240V, but Im a retired electrical trade teacher so im permitted to nag. Take care.
Cheers

Teacher, your homework assignment is to determine what is wrong with your reasoning in #3 (I mean the first #3, not the second #3).

03_Troopy · Guru

/|\ not \|/, if it's O/C on the 2M range, it'll still be O/C on lower ranges. If there is a short to ground, the CCT BKR should open.

-- Edited by 03_Troopy on Thursday 2nd of July 2015 06:39:48 PM

oldtrack123 · Guru

03_Troopy wrote:
/|\ not \|/, if it's O/C on the 2M range, it'll still be O/C on lower ranges. If there is a short to ground, the CCT BKR should open.

-- Edited by 03_Troopy on Thursday 2nd of July 2015 06:39:48 PM

And Ditto to that!! biggrin

Absolutely no need to worry about using any other range than the 200 Ohm for checking the element

I do not know the element wattage for the heater but any reading above much above 60 Ohms would indicate a faulty element {IMHO

]That is around what a what a 1000W element should be

If it is a 1400W element it read even lower

PeterQ

dorian · Guru

I hope that my post was not seen as anything other than a lighthearted dig at what was obviously a brain fart. I certainly did not mean to suggest that PhilC doesn't know his stuff.

A "brain fart" is a term for an inexplicably stupid error in a straightforward task made by someone with abundant skill and experience. Everyone is prone to them.

http://articles.mercola.com/sites/articles/archive/2010/01/12/scientists-figure-out-the-cause-of-brain-farts.aspx

Knowledge speaks, but wisdom listens.