inverter generator

onion

onion

Full Member
Posts
133
Likes
76
Hi all can someone help me with a generator prob,I've just bought a Clarke 1kw & it said it has to be earthed , does it have to be if plugged in to the van, I've never heard anyone talking a bought earthing a suitcase generator, thanks onion.
 
You should have an "Earth" to all 240V appliances. The usual way is to have an earth trip which trips a lot faster than a burn out type fuse.
 
I would run the power from the Genny into your external hook up through the van consumer unit which has an earth to the van and RCD breakers on the socket circuits. Were you thinking of doing it another way?
 
I have seen generators which are supplied with a copper earth spike to drive into the ground and connect to. These generators would also have an RCD fitted and the spike would be needed for it to operate.

Not very clear as to the protective devices fitted to your generator so will not comment. I have never yet seen anybody use an earth other than in commercial installations.

When using a generator, for the MH RCD to operate the earth conductor needs to be complete, the generator to be wired with an earth point. The spike is used to cover for the earth being incomplete but both ends would need a spike in the case of a MH
 
Last edited:
I've got one of these and just made up an earthing spike that I drive into the ground alongside the genny. The machine has an earthing point with a wing nut. I've never had a problem although not used it much with the MH mainly with lighting or power tools. I do feel safer having the earth and trips when working outside.

Dai
 
Plug the genny into the van and fire up, now go and press the test button on the RCD - does it operate? The RCD needs an earth path to operate, without which it will do nothing in the event of a fault. The normal earth path for your van is through the supply cable.

Most people never seem to bother with an earth whilst using a genny and leave it floating, a few convert the genny to a TNC supply thus negating the need for an earth.

Edit: Thinking about it, the modern RCBO test button is only a mechanical test button testing the mechanical side of the trip and not the earth path. So ignore the sentence in red itallics.
 
Last edited:
Simple thing to do is get a short length of wire and a METAL tent peg. Tent peg in to the ground and wrap the wire around it. Connect the other side of the wire to any metal part if the generator. It's now earthed!
 
DTDog said:
Simple thing to do is get a short length of wire and a METAL tent peg. Tent peg in to the ground and wrap the wire around it. Connect the other side of the wire to any metal part if the generator. It's now earthed!
Click to expand...

Would you do the same at the MH?
 
Last edited:
shortcircuit said:
And would you do the same at the MH, otherwise what have you achieved?
Click to expand...

Why would you need to do the same at the MH? If the genny is earthed via stake/tent peg that earth path should contiue through the supply cable and into the MH. It would be beneficial to fit a plug in RCD at the genny to protect the complete circuit.

The earth stake can have a theoretical resistance of up to 1666 Ohms however less than 1000 Ohms should be easy to obtain and will suffice.
 
I've been around motor racing paddocks for years where gennys are running all day long and never seen anyone use an earth spike when they are using tools or compressors, we've never bothered and not had a problem yet. I'm not saying you shouldn't but I've not seen any problems through not using one and believe me there are loads of them working on a race weekend.
 
drewdt3 said:
I've been around motor racing paddocks for years where gennys are running all day long and never seen anyone use an earth spike when they are using tools or compressors, we've never bothered and not had a problem yet. I'm not saying you shouldn't but I've not seen any problems through not using one and believe me there are loads of them working on a race weekend.
Click to expand...
As I said most people don't bother, myself included on the rare few times I use one, however if I was using one for hours at a time and in a metal MH, then the very least I would do is put in a small spike if possible.

Most gennys that have a metal frame which is scratched back to bare metal when this is in contact with the ground, particulary in damp soil then that should be sufficient for earthing when using an 30mA RCD.
 
sparrks said:
Why would you need to do the same at the MH? If the genny is earthed via stake/tent peg that earth path should contiue through the supply cable and into the MH. It would be beneficial to fit a plug in RCD at the genny to protect the complete circuit.

The earth stake can have a theoretical resistance of up to 1666 Ohms however less than 1000 Ohms should be easy to obtain and will suffice.
Click to expand...

In the unlikely event of the hook up cable earth conducter being faulty
 
shortcircuit said:
In the unlikely event of the hook up cable earth conducter being faulty
Click to expand...

You would have to be pretty unlucky for that scenario to happen.

Out of curiosity how often or not do people test or have their 240V installation checked? including hookup leads - RCD test times, insulation resistance, continuity and for mechanical damage.

I try and check/test mine once a year, but it might be a couple of years between usage.
 
shortcircuit said:
Test mine very similar to yourself as I still have Alphatek so really no excuses
Click to expand...

Sadly I guess that we are one of a very small minority who do, and that's probably only because we have the gear to do it - if I had to pay to take it to someone to do the tests then maybe I wouldn't bother.
 
Thanks palls for replying think ill go with the tent peg,just didn't think of this I thought suitcase gens were just plug & go, thanks again .
 
Roger said:
You should have an "Earth" to all 240V appliances. The usual way is to have an earth trip which trips a lot faster than a burn out type fuse.
Click to expand...

I would question that. It's not necessary to have an earth on all 240v appliances. "Double insulated" appliances or appliances fed by isolating transformers do not. (but may do for different reasons)
Also an RCD is different from an MCB. A Miniature Circuit Breaker (MCB) is the modern equivalent of a fuse and, as you say, will trip faster. But it has nothing to do with earth trips. MCB's protect the wiring and appliances from excessive current flow in the event of a fault. They do nothing to protect the user. RCD's may be called earth trips as they sense unbalance between the live and neutral wires. Unbalance would occur if some form of leakage was causing current to go somewhere else - usually to earth directly or possibly through a person. So an RCD is for safety.

I've looked at an ad for the Clarke 1Kw and it does not say if it has a "floating mains output" But as you say it comes with an instruction to earth it I guess it does not. Some generators do have floating outputs and in that case there is no live and neutral as such - just 230v between the two conductors and no voltage with respect to earth. Just like an isolating transformer. So, unless you get across BOTH those wires you cannot get a shock. If you do manage to that - perhaps while working on it while it running -then no MCB, RCD or anything else will save you. So, There is no need for an earth spike

If the generator has an internal connection between ONE of the mains wires and the frame of the generator then a "neutral" has been created. The other wire is now the "live" wrt to the frame and in general terms, to earth. In this case you will not only need to connect your generator earth wire through to your van earth circuits but you will need to provide a path to earth - a spike. This is needed for any RCD's installed on the generator or the van to work. Unlike the old days when the earth had to be low enough impedance to pass the whole fault current (until a fuse blew) the spike only needs to pass the tripping current from the RCD - usually 30ma.

So it's important to know if a generator has a floating output - sometimes called a floating neutral - or not.
 
drewdt3 said:
I've been around motor racing paddocks for years where gennys are running all day long and never seen anyone use an earth spike when they are using tools or compressors, we've never bothered and not had a problem yet. I'm not saying you shouldn't but I've not seen any problems through not using one and believe me there are loads of them working on a race weekend.
Click to expand...

Mine for a starters, I use my genny most weekends thru the race season and never earthed it............... No problem.
 
cornishlad said:
I would question that. It's not necessary to have an earth on all 240v appliances. "Double insulated" appliances or appliances fed by isolating transformers do not. (but may do for different reasons)
Also an RCD is different from an MCB. A Miniature Circuit Breaker (MCB) is the modern equivalent of a fuse and, as you say, will trip faster. But it has nothing to do with earth trips. MCB's protect the wiring and appliances from excessive current flow in the event of a fault. They do nothing to protect the user. RCD's may be called earth trips as they sense unbalance between the live and neutral wires. Unbalance would occur if some form of leakage was causing current to go somewhere else - usually to earth directly or possibly through a person. So an RCD is for safety.

I've looked at an ad for the Clarke 1Kw and it does not say if it has a "floating mains output" But as you say it comes with an instruction to earth it I guess it does not. Some generators do have floating outputs and in that case there is no live and neutral as such - just 230v between the two conductors and no voltage with respect to earth. Just like an isolating transformer. So, unless you get across BOTH those wires you cannot get a shock. If you do manage to that - perhaps while working on it while it running -then no MCB, RCD or anything else will save you. So, There is no need for an earth spike

If the generator has an internal connection between ONE of the mains wires and the frame of the generator then a "neutral" has been created. The other wire is now the "live" wrt to the frame and in general terms, to earth. In this case you will not only need to connect your generator earth wire through to your van earth circuits but you will need to provide a path to earth - a spike. This is needed for any RCD's installed on the generator or the van to work. Unlike the old days when the earth had to be low enough impedance to pass the whole fault current (until a fuse blew) the spike only needs to pass the tripping current from the RCD - usually 30ma.

So it's important to know if a generator has a floating output - sometimes called a floating neutral - or not.
Click to expand...

If it's 230v between phases then wouldn't it be 115v phase to earth? similar to a 110v transformer which is 110v across phases and 55v phase to earth?
 
I believe that a 110v site transformer is a particular case of an isolating transformer. If it has a centre tap and that CT is earthed, then that would mean, as you say, that there is 55v wrt earth on either phase. That is deemed to be a relatively "safe" voltage. I'm sure there is a good reason for doing that (as opposed to leaving it floating) but I don't know what it is.
The same principle would apply to generators if the alternator had an earthed centre tap but I don't believe this would ever be done with a 230 ac generator that UK motorhomers would be faced with . If the generator was an inverter type it may be extremely difficult to achieve such a voltage split anyway. There may be 110v site generators that do have the 55-0-55 output..I've never looked into that.
 
Last edited by a moderator:
You must log in or register to reply here.

Users who viewed this discussion (Total:0)

Back
Top