external lights setting off trip

Have just wired in two 58W fluorescent striplights to sit under decking & it looks pretty good, when it works. Problem is, sometimes when I switch on, the main trip on fusebox goes off. The two PIR floods I wired in at the same time work fine. Can't find any fault with my wiring! The lights are connected to a ring main via a switched FCU. Any ideas, please?? Thanks in advance, Paul.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Are these proper external fluorescent lights or standard indoor type
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Hi Paul,
Check that the cable you've used is not clipped to tightly and causing to much of an earth leakage or that you haven't put a nail through or clipped against anything sharp which is cutting into the insulation.
Make sure you've made the connections properly in the Spur Unit, or simply take the connections out of the Spur (FCU) and put a plug top on the end of the cable and plug it in to see if it still trips the MCB in the Consumer Unit.
Are the Floods also coming on with fluorescent lights ? as this may be taking to much load all at once and also causing the breaker to trip.
Sorry, so many things could be wrong that I could go on all night with things to check, so please advise of anything else which you've done to create this installation.
--
www.basecuritysystems.no-ip.com
Outgoing mail is certified Virus Free.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

What do you mean by 'main trip'? Is it the MCB serving that circuit or something like an RCD main switch, protecting several circuits?
If it is only an MCB, it could be the start-up surge from switching on the fluorescents. Experience suggests that switching more than about 70W at a time can produce intermittent tripping of a standard 6 amp MCB. Your options are to uprate the MCB to at least 10A (if the cable is suitable for this current), to fit a type C / type 3 MCB, or to fit separate switches to the lights and turn them on one at a time. The last is probably the easiest and cheapest option.
Colin Bignell
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
paul wood wrote:

Yeah. Right.
Upgrade the main RCD to 100mA, and split the consumer unit so the rings that represent a hazard are on a separate 30mA RCD.
I got so sick of triping on my box, now its all om 100mA, and there ain't enough room to split it and I can't be arsed either.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thanks for the answers, sorry my question was a bit lacking in essential details! The fluo lights are proper external ones, & my connections all seem OK. It is the main 30mA RCD that trips, the MCB is not affected. The lights were working fine for about a week & have only just started playing up - nothing has changed in that time as far as I know! Perhaps the RCD is just too sensitive?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.