IET logo
 
IET
Decrease font size
Increase font size
Topic Title: Using 100mA RCD? is it acceptable?
Topic Summary:
Created On: 23 September 2013 07:28 AM
Status: Post and Reply
Linear : Threading : Single : Branch
Search Topic Search Topic
Topic Tools Topic Tools
View similar topics View similar topics
View topic in raw text format. Print this topic.
 23 September 2013 07:28 AM
User is offline View Users Profile Print this message



Tom1987

Posts: 2
Joined: 23 September 2013

Hi all just needing a little help, currently working in the food industry each machine currently has a 30mA trip built in every socket for each individual machine, fuse boards are upstairs in a low risk area, in the db we also have 30mA RCD feedind each socket, due to nuisence tripping it trips both downstairs and upstairs RCD. could i change the upstairs RCD for a 100mA to combat this, I have just started in my career in industry coming from a house bashing environment where 30mA is the norm to meet current regs

cheers
 23 September 2013 07:55 AM
User is offline View Users Profile Print this message



cblackha

Posts: 79
Joined: 21 January 2003

what's the earth leakage current for the various machines?

Standards such as EN60204 allow high levels of leakage current provided that various safeguards are in place such as use of a suitably large bonding conductor and / or automatic disconnection of supply in case of loss of bonding conductor continuity.
 23 September 2013 10:16 AM
User is offline View Users Profile Print this message



AJJewsbury

Posts: 11775
Joined: 13 August 2003

Hi all just needing a little help, currently working in the food industry each machine currently has a 30mA trip built in every socket for each individual machine, fuse boards are upstairs in a low risk area, in the db we also have 30mA RCD feedind each socket, due to nuisence tripping it trips both downstairs and upstairs RCD. could i change the upstairs RCD for a 100mA to combat this,

If you have two 30mA RCDs in series and both are tripping out, then changing one to 100mA won't stop the 30mA one from tripping.

I have just started in my career in industry coming from a house bashing environment where 30mA is the norm to meet current regs

There's no universal demand for 30mA RCDs in the regs - so you need to work out why (or indeed if) RCDs are needed. Are the sockets for general use or dedicated for each machine? (if the latter you can usually omit 30mA RCD protection - subject to a local risk analysis of course), are all-insulated cables concealed in walls? (if not, you probably don't need 30mA RCD protection on that score). Presumably none of this in in a room containing a bath or shower.

As cblackha suggests, if you're getting high leakage currents from certain items of equipment (and it's not down to the equipment being faulty) then you need to consider high protective current precautions (regardless of the RCD situation) - see section 543.7 of BS 7671.

- Andy.
 23 September 2013 12:24 PM
User is offline View Users Profile Print this message



Tom1987

Posts: 2
Joined: 23 September 2013

The machines are indeed not near a bath or shower but working in the food industry and hose pies are used every day to clean down and its rather wet to say the least so i would say RCD are a must even though cables are run in conduit and are visible. RCD's enclosed in the IP rated sockets were put in as a means of ease to cut down on downtime to hopefully eliminate us from going upstairs to re energise the circuit, the problem we've got is most machines are inverter driven which is nuisence tripping the RCD, by changing the one at source upstairs to 100mA will this combat the fault and is it ok to do so?? bonding is nowhere near visible on any machine which i think is a major problem but nobody seems interested and a total different subject, all scales, cutters etc in the factory are 230/415V should these be low voltage due to the wet conditions?? which is also a total different subject matter.

cheers
 23 September 2013 12:42 PM
User is offline View Users Profile Print this message



Finnley

Posts: 3
Joined: 23 September 2013

Hi

You say you have inverters, what type of RCD is being used?
 23 September 2013 01:09 PM
User is offline View Users Profile Print this message



AJJewsbury

Posts: 11775
Joined: 13 August 2003

by changing the one at source upstairs to 100mA will this combat the fault and is it ok to do so

Are the "upstairs" RCDs protecting one socket each, or are there several sockets on the same upstairs RCD?

The machines are indeed not near a bath or shower but working in the food industry and hose pies are used every day to clean down and its rather wet to say the least

But the people not normally wet, naked and barefooted? (unlike a bathroom)

- Andy.
 23 September 2013 03:26 PM
User is offline View Users Profile Print this message



cblackha

Posts: 79
Joined: 21 January 2003

No offence intended here, but the issue of RCDs should not be decided in isolation here.

Machines are covered by Machinery Directive ( and a whole load of H&S stuff) and cleaning/maintenance in one of the things that should be considered before the machinery is put into service.

There must be a risk assessment
It must be safe to clean the machines and I'm not sure that using an RCD to minimise current in event of electrocution should really be the 1st option on the list.

If water is required, and power really must be on, then someone should be looking at this much closer and however you are asked to connect the machines should be part of a clearly defined strategy to ensure that the machinery is safe. This is outside the remit of someone being asked to provide external power connections.

Charlie
Statistics

See Also:



FuseTalk Standard Edition v3.2 - © 1999-2014 FuseTalk Inc. All rights reserved.