ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals

ECN Shout Chat
Top Posters(30 Days)
Admin 19
Recent Posts
fuse rejectors
by NORCAL. 03/29/17 01:44 AM
Old decora style outlets
by NORCAL. 03/29/17 01:41 AM
NFPA stuff
by gfretwell. 03/28/17 08:08 PM
Anyone hiring inspectors?
by HotLine1. 03/27/17 08:03 AM
ESA Arc flash course
by TheShockDoctors. 03/24/17 10:15 AM
New in the Gallery:
SE cable question
Popular Topics(Views)
231,833 Are you busy
166,727 Re: Forum
160,851 Need opinion
Who's Online Now
0 registered members (), 61 guests, and 11 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#146270 - 11/22/06 09:37 AM Portable Generators  
Kenbo  Offline
Member
Joined: Apr 2006
Posts: 233
Scotland
Quick question

If you use a portable generator should you use it with an RCD, or is it pointless as the generating set is isolated from earth?

Thinking of the small ones popular with caravans and small works.


der Gro├čvater

Test Equipment:
Large Selection of Test Equipment For Electrical, HVAC, Test & Measurement
Large Selection of Test Equipment For Electrical, HVAC, Test & Measurement

#146271 - 11/22/06 10:36 AM Re: Portable Generators  
32VAC  Offline
Member
Joined: Jun 2004
Posts: 202
Alice Springs, NT, Australia
In regards to the earthing, depends if the unit has been fitted with a MEN link. Which country are you in?


#146272 - 11/22/06 02:59 PM Re: Portable Generators  
Wolfgang  Offline
Member
Joined: Sep 2005
Posts: 153
the very West of Germany
Kenbo being from Scotland, I'd suppose that the small units work as IT-systems. This means they are probaby isolated. RCD won't function in this case and is not necessary. Often there is even no metal in the place of the earth pin (or brackets on the continent).


#146273 - 11/22/06 04:55 PM Re: Portable Generators  
Kenbo  Offline
Member
Joined: Apr 2006
Posts: 233
Scotland
32VAC sorry forgot the interantional scope of this forum. As Wolfgang says I am in Scotland so working with the UK system. (MEN link is that an earth-neutral link?)

Wolfgang, that is my thinking also but I do not know for shure I will have to go and look at one now.

I was just reading my issue of "Wiring Matters" and there is an artical about small generators and this para got me wondering
..................
A small single phase generator is often run as a floating system. A means of earthing is not required. In such a system the generator is deliberately not connected to external metallic parts nor is one pole of the single phase electrical system connected to earth.
In such a system there is no path for an earth fault current to return to the 'seperated' winding of the generator. Safety must be ensured by meeting the following conditions....."
...........................
(no mention of RCDs)

The magazine is not yet posted on the net but I will put in a link once it has been

Kenny


der Gro├čvater

#146274 - 11/23/06 03:17 AM Re: Portable Generators  
32VAC  Offline
Member
Joined: Jun 2004
Posts: 202
Alice Springs, NT, Australia
MEN is multiple earth neutral where the neutral & earth are tied together at switchboard.

A look at Australian Standard 3010:2005 chapter 4 shows two different methods of connection. The first picture is of a genset with the earth not tied to the neutral & using double pole switching of the outlets.

The other picture shows an RCD fitted to a portable genset with the lines side of the RCD connected to the earth point. The use of the RCD permits the use of single pole switching outlets.

If I can find an online copy of these pictures, I will arrange to have them put in this thread.


#146275 - 11/23/06 09:11 AM Re: Portable Generators  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
If the generator output is truly floating, then an RCD would be of little use.

The issue of a bond between one side of the generator output and its frame raises some more points though. If such a bond is in place, then I'd definitely want the genset earthed, otherwise an accidental earth fault on the other side would raise the genset frame and everything else connected to it to 240V.


#146276 - 01/25/07 02:00 PM Re: Portable Generators  
lyledunn  Offline
Member
Joined: Jun 2002
Posts: 159
N.Ireland
It is generally accepted that such arrangements are confined to a single circuit supplying a single class 2 tool. Thus the possibility of a double fault is very much reduced.


regards

lyle dunn

#146277 - 01/27/07 07:00 AM Re: Portable Generators  
Trumpy  Offline


Member
Joined: Jul 2002
Posts: 8,211
SI,New Zealand
32VAC,
I know the diagrams you are talking about.
I just can't rip them from a PDF file I have here on my computer.
Can anyone else help?.
Send me an e-mail if you want the file.


Let's face it, these days if you're not young, you're old - Red Green grin


Member Spotlight
RH1
RH1
California
Posts: 22
Joined: August 2009
Show All Member Profiles 
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.015s Queries: 14 (0.003s) Memory: 0.7908 MB (Peak: 0.9520 MB) Zlib enabled. Server Time: 2017-03-30 08:47:51 UTC